Search

The development of composites with antibacterial activity represents an important strategy to avoid side effects such as increasing bacterial resistance to antibiotics. In particular, the green synthesis of metal nanoparticles avoids the use of hazardous chemical compounds and introduces the intrinsic beneficial properties of plant-derived compounds. Herein, the reduction of gold salt into metal nanoparticles was provided by the action of a cationic polymer derived from tannin (Tanfloc®). Comparative activity of antibacterial agents (pure Tanfloc and Au NPs—Tanfloc) at different concentrations were evaluated in terms of the antibiofilm activity, kill-time assays and inhibition haloes confirming the antibacterial activity of the Tanfloc that is reinforced by the incorporation of reduced gold nanoparticles, resulting in the complete elimination of S. aureus from an initial concentration of 108 CFU/mL after 120 min of reaction of Au NPs + Tanfloc solution in association with strong inhibition of the biofilm formation attributed to the Tanfloc.

Despite the existence of many different food preservation methods, foodborne pathogens are still the most common related problems to dairy products. Developing naturally alternative techniques to control such problems is necessary. This research was planned to assess the bacteriological quality of yoghurt samples commercially available in Kafr El-Sheikh city, Egypt. Also to study the impact of natural antibacterial agents on the inhibition of selected foodborne pathogens artificially inoculated in yoghurt samples. The obtained results revealed poor bacteriological quality of the examined yoghurt samples, as total staphylococci and coliforms were detected in 80% and 90% yoghurt samples, with mean values of 2.4 ×103±0.13× 103cfu/gm and 3.6×105± 2.4×105 MPN/gm, respectively. S. aureus was noticed in 4% of examined samples, polymerase chain reaction (PCR) confirmed the pres­ence of virulence adhesion gene (clfA) in one isolate. E. coli was detected in 14% of yoghurt samples, then serologically identified as O146:H5 (2), O111:H2 (2), O125:H11 (1), O26:H10 (1) and O158:H7 (1). Artificially inoculated yoghurt with S. aureus (7.39 log cfu/gm) and E. coli (8.3 log cfu/gm), were used to investigate the ability of hen egg-white lysozyme either with LAB classic or with ABT-5 (L. acidophilus LA5+ S. thermophiles + Bifidobacterium Bb12) starter cultures to inhibit the growth of these pathogens. During refrigerated storage, all yoghurt batches showed a reduction in pH value. It was observed that both pathogens couldn't be detected in the yoghurt batch containing LAB classic starter + heated lysozyme. Furthermore, S. aureus was completely inhibited in that containing ABT-5 cultures alone, while E. coli decreased by 6.23 log. Conversely, there was not complete inhibition in other batches containing (LAB classic starter, LAB classic starter+ native lysozyme, ABT-5 culture+ native lysozyme and ABT-5 culture+ heated lysozyme) as the reduction rate during all storage periods for S. aureus count was 1.66, 2.63, 4.47 and 4.19 log, While for E. coli count was 3.3, 3.81, 5.53 and 4.89 log, respectively. This study highlighted the importance of adding natural antibacterial agents like lysozyme with LAB culture to yoghurt as a bio-control strategy to overcome foodborne pathogens that cause a public health hazard.

Background:S. aureusis the most common bacteria associated with both community and hospital associated infections. It is associated with skin and wound infection, pneumonia, endocarditis, septic arthritis, osteomyelitis. Objectives:The present study aimed to estimate the prevalence of infectious disease caused by Methicillin sensitiveStaphylococcus aureusamong community and hospital acquired infections in Khartoum State, Sudan. Methods:A cross-sectional laboratory-based study was conducted during the period from November 2020 to January 2021. To isolate and identifyS. aureus, theconventional method and protein A latex test were used. All isolated organisms were tested for their in-vitro antimicrobial susceptibility against methicillin (MET 5μg) disc using the Kirby-Baur disk diffusion method to detect MSSA. Result:The result showed a high frequency of community infection (80%). The majority of the isolates were isolated from patients with respiratory tract infection (28.7%), and the result showed that RTI more common on community infection (33.7%). Conclusion:The present study concluded that male more infected by MSSA and the highest frequency of isolates was in the age group more than 45 years. The present study highlighted that RTI is predominantly the site of infection by MSSA. The present study showed that RTI more common on community infection.

The aim:study of the effectiveness of environmentally safe disinfectants against P. aeruginosa and pathogens of the main bacteriosis of poultry at test facilities. Materials and methods.To study the antimicrobial action of the investigated disinfectants against a mixture of epizootic cultures of E. coli, P. aeruginosa, S. aureus, S. typhimurium, isolated from poultry, bacteriological studies were carried out on test objects: galvanized iron, wooden bars (painted and unpainted), red brick, cutouts from plaster, size 10 × 10 cm. Results.The working solutions of the new disinfectant "Dezsan" were studied in comparison with the control agents: "Virocid" and "Bi-dez" at a concentration of 0.01; 0.1; 0.25; 0.5; 1; 1.5 % in relation to suspension cultures of E. coli, P. aeruginosa, S. aureus, S. typhimurium. In this case, it was established, that the "Dezsan" agent showed an antimicrobial effect on rough test objects after exposure for 3 hours at a concentration of 0.1 %, and at a concentration of 0.25 % - for 1 hour. On smooth surfaces, the agent neutralized bacterial cultures at a concentration of 0.1 % after exposure for 1 hour. The preparation "Bi-dez" at a concentration of 0.25 % was effective on smooth surfaces after exposure for 1 hour, on rough surfaces (brick, plaster) - at a concentration of 0.5 % after exposure for 3 hours or more. The working solution of 1 % concentration neutralized bacterial cultures on all types of surfaces after exposure for 1 hour or more. "Virocid" agent after exposure for 1 hour neutralized bacterial cultures on smooth surfaces in concentrations of 0.25 % and higher; on rough surfaces, the growth of cultures was not detected when using a 0.5 % solution. Conclusions.Environmentally safe disinfectants "Dezsan" and "Shumerske sryblo" compared to the control ones ("Bi Dez" and "Virotsid") show an active antimicrobial effect at a concentration of 0.25 % and 3 %, respectively, against the suspension of epizootic cultures of E. coli, P. aeruginosa, S. aureus and S. typhimurium on different types of production surfaces, which justifies the feasibility of their use based on the principle of rotation of disinfectants for the prevention of bacterial pseudomonosis of poultry

This paper aims to report the synthesis of two new organotin(IV) carboxylate derivatives, triphenyltin(IV) 4-aminobenzoate (2) and triphenyltin(IV) 4-nitrobenzoate (3) and to examine their antibacterial activity as a disinfectant. These compounds were prepared by reacting triphenyltin(IV) hydroxide (1) with 4-aminobenzoic acid and 4-nitrobenzoic acid, respectively. Compound (2) was obtained as a yellow solid with a yield of 84.09% and compound (3) in the form of a white solid with a yield of 80.70%. These compounds were well characterized using UV-Vis spectrometry, FT-IR spectrometry and NMR spectroscopy. The bioactivity test as a disinfectant was tested against Salmonella typhosa and Staphylococcus aureus. The activity test was carried out by measuring the optical density (OD) of the tested compounds with concentration variations of 5x10-3, 1x10-3, and 5x10-4 M in methanol and 5% dimethyl sulfoxide (DMSO), commercial Wipol (2.5% pine oil) was used as a positive control with observations monitored at contact times of 0, 5, 10, and 15 minutes. The results showed that of both compounds were active against the two bacteria compared to the positive control with compound 3 found to be more active than compound 2.

Royal jelly (RJ) has lots of compounds such as protein, vitamins, and a variety of bioactive compounds (10-hydroxy-2-decanoic or 10-HDA acids). 10-HDA is a lipid fraction component in RJ content with antibacterial and immunomodulatory activity. RJ proteins that have antimicrobial, antifungal, anti-tumor, antidiabetic, and antihypertensive properties. The authors continue their research about the effect of RJ on the inhibitory strength of the given antibacterial activity. L. monocytogenes, S. aureus, and E. coli were among the microbes studied in this research. This study used an experimental method with a complete randomized design (CRD) of 5 treatments and 4 replications, if the treatment showed a noticeable effect (PL. monocytogenes proved that the second treatment had a higher inhibitory power of 30.94±25.786b, in S. aureus, the second treatment gave a moderate inhibitory power of 9.013±1.841a, and in E. coli, the second treatment gave a weak inhibitory power of 3.24±3.748a. The conclusion of studies showed royal jelly with dilution variety could be antimicrobial agent and to be strongest inhibitor in L. monocytogenes and lowest in E. coli. The suggestion of studies needs management in the isolates of bacteria available and should be estimated before we do the research about antimicrobial activity inhibitors.

Composites of Ag and TiO2 nanoparticles were synthesized in situ on cotton fabrics using sonochemical and solvothermal methods achieving the successive formation of Ag-NPs and Ti-NPs directly on the fabric. The impregnated fabrics were characterized using ATR-FTIR spectroscopy; high-resolution microscopy (HREM); scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS); Raman, photoluminescence, UV-Vis, and DRS spectroscopies; and by tensile tension tests. Results showed the successful formation and impregnation of NPs on the cotton fabric, with negligible leaching of NPs after several washing cycles. The photocatalytic activity of supported NPs was assessed by the degradation of methyl blue dye (MB) under solar and UV irradiation revealing improved photocatalytic activity of the Ag–TiO2/cotton composites due to a synergy of both Ag and TiO2 nanoparticles. This behavior is attributed to a diminished electron–hole recombination effect in the Ag–TiO2/cotton samples. The biocide activity of these composites on the growth inhibition of Staphylococcus aureus (Gram+) and Escherichia coli (Gram−) was confirmed, revealing interesting possibilities for the utilization of the functionalized cotton fabric as protective cloth for medical applications.

Silver nanoparticles (AgNPs) with broad-spectrum antimicrobial properties are gaining increasing interest in fighting multidrug-resistant bacteria. Herein, we describe the synthesis of AgNPs, stabilized by polyvinyl alcohol (PVA), with high purity and homogeneous sizes, using radiolysis. Solvated electrons and reducing radicals are induced from solvent radiolysis and no other chemical reducing agents are needed to reduce the metal ions. Another advantage of this method is that it leads to sterile colloidal suspensions, which can be directly used for medical applications. We systematically investigated the effect of the silver salt precursor on the optical properties, particle size, and morphology of the resulting colloidal AgNPs. With Ag2SO4 precursor, the AgNPs displayed a narrow size distribution (20 ± 2 nm). In contrast, AgNO3 and AgClO4 precursors lead to inhomogeneous AgNPs of various shapes. Moreover, the optimized AgNPs synthesized from Ag2SO4 were stable upon storage in water and phosphate-buffered saline (PBS) and were very effective in inhibiting the growth of Staphylococcus aureus (S. aureus) at a concentration of 0.6 μg·mL−1 while completely eradicating it at a concentration of 5.6 μg·mL−1. When compared with other AgNPs prepared by other strategies, the remarkable bactericidal ability against S. aureus of the AgNPs produced here opens up new perspectives for further applications in medicine, cosmetics, the food industry, or in elaborating antibacterial surfaces and other devices.

The poor bioavailability of antibiotics at infection sites is one of the leading causes of treatment failure and increased bacterial resistance. Therefore, developing novel, non-conventional antibiotic delivery strategies to deal with bacterial pathogens is essential. Here, we investigated the encapsulation of two fluoroquinolones, ciprofloxacin and levofloxacin, into polymer-based nano-carriers (nano-antibiotics), with the goal of increasing their local bioavailability at bacterial infection sites. The formulations were optimized to achieve maximal drug loading. The surfaces of nano-antibiotics were modified with anti-staphylococcal antibodies as ligand molecules to target S. aureus pathogens. The interaction of nano-antibiotics with the bacterial cells was investigated via fluorescent confocal microscopy. Conventional tests (MIC and MBC) were used to examine the antibacterial properties of nano-antibiotic formulations. Simultaneously, a bioluminescence assay model was employed, revealing the rapid and efficient assessment of the antibacterial potency of colloidal systems. In comparison to the free-form antibiotic, the targeted nano-antibiotic exhibited enhanced antimicrobial activity against both the planktonic and biofilm forms of S. aureus. Furthermore, our data suggested that the efficacy of a targeted nano-antibiotic treatment can be influenced by its antibiotic release profile.

Medical devices are often vulnerable to colonization by nosocomial pathogens (bacteria), leading to infections. Traditional sterilization methods may not always be effective, and as a result, alternative options are being explored to prevent microbial contamination. Recently, scientists are emphasizing using plant-derived essential oils that possess inherent antibacterial properties to produce antimicrobial coatings using plasma polymerization technology carried out at atmospheric pressure (AP). This approach shows promise compared to other coating strategies that need several processing steps, including a high-vacuum system, and are laborious, such as the immobilization of antimicrobial materials on precoated layers in the low-pressure plasma polymerization approach. The present study demonstrates the potential of AP plasma polymerization for producing thin films with excellent antibacterial properties and surface characteristics. The resulting coatings are stable, smooth, and have high wettability, making them ideal for repelling bacteria. The calculated zeta potential and deposition rate for the films are also favorable. These AP plasma-polymerized thin films created from carvone show a reduction rate of more than 90% for Escherichia coli and Staphylococcus aureus bacteria. Our computational docking studies also reveal strong binding interactions between the original carvone monomer and both bacteria. The study suggests that these AP plasma-produced coatings have great potential as antibacterial coatings for biomedical devices.

According to the Food and Agriculture Organization of the United Nations, pork remains the most consumed meat in the world. Consequently, it is very important to ensure that it is of the highest microbiological quality. Many of the pathogens that cause lymph node lesions in pigs are zoonotic agents, and the most commonly isolated bacteria are Mycobacterium spp., Streptococcus spp., Staphylococcus aureus and Rhodococcus equi (synonymous with Prescottella equi). The prevention and treatment of zoonotic infections caused by these bacteria are mainly based on antimicrobials. However, an overuse of antimicrobials contributes to the emergence and high prevalence of antimicrobial-resistant strains, which are becoming a serious challenge in many countries. The aim of this study was to evaluate the genetic diversity and antimicrobial resistance of the Streptococcus spp. (n = 48), S. aureus (n = 5) and R. equi (n = 17) strains isolated from swine lymph nodes with and without lesions. All isolates of S. dysgalactiae, S. aureus and R. equi were subjected to PFGE analysis, which showed the genetic relatedness of the tested bacteria in the studied pig populations. Additionally, selected tetracycline and macrolide resistance genes in the streptococcal strains were also studied. The results obtained in the present study provide valuable data on the prevalence, diversity, and antimicrobial resistance of the studied bacteria. Numerous isolated bacterial Streptococcus spp. strains presented resistance to doxycycline, and almost half of them carried tetracycline resistance genes. In addition, R. equi and S. aureus bacteria presented a high level of resistance to beta-lactam antibiotics and to cefotaxime, respectively.

Contamination of food by pathogens can pose a serious risk to health. Therefore, monitoring for the presence of pathogens is critical to identify and regulate microbiological contamination of food. In this work, an aptasensor based on a thickness shear mode acoustic method (TSM) with dissipation monitoring was developed to detect and quantify Staphylococcus aureus directly in whole UHT cow’s milk. The frequency variation and dissipation data demonstrated the correct immobilization of the components. The analysis of viscoelastic properties suggests that DNA aptamers bind to the surface in a non-dense manner, which favors the binding with bacteria. The aptasensor demonstrated high sensitivity and was able to detect S. aureus in milk with a 33 CFU/mL limit of detection. Analysis was successful in milk due to the sensor’s antifouling properties, which is based on 3-dithiothreitol propanoic acid (DTTCOOH) antifouling thiol linker. Compared to bare and modified (dithiothreitol (DTT), 11-mercaptoundecanoic acid (MUA), and 1-undecanethiol (UDT)) quartz crystals, the sensitivity of the sensor’s antifouling in milk improved by about 82–96%. The excellent sensitivity and ability to detect and quantify S. aureus in whole UHT cow’s milk demonstrates that the system is applicable for rapid and efficient analysis of milk safety.

Staphylococcus aureus is one of the most prevalent pathogens causing bovine mastitis in the world, in part because of its ease of adaptation to various hosts and the environment. This study aimed to determine the prevalence of S. aureus in Colombian dairy farms and its relationship with the causal network of subclinical mastitis. From thirteen dairy farms enrolled, 1288 quarter milk samples (QMS) and 330 teat samples were taken from cows with positive (70.1%) and negative California Mastitis Test (CMT). In addition, 126 samples from the milking parlor environment and 40 from workers (nasal) were collected. On each dairy farm, a survey was conducted, and the milking process was monitored on the day of sampling. S. aureus was identified in 176 samples, i.e., 138 QMS, 20 from teats, 8 from the milking parlor environment, and 10 from workers’ nasal swabs. Isolates identified as S. aureus underwent proteomics (clustering of mass spectrum) and molecular (tuf, coa, spa Ig, clfA, and eno genes) analysis. Regarding proteomics results, isolates were distributed into three clusters, each with members from all sources and all farms. Concerning molecular analysis, the virulence-related genes clfA and eno were identified in 41.3% and 37.8% of S. aureus isolates, respectively. We provide evidence on the circulation of S. aureus strains with limited variability among animals, humans, and the environment. The parameters with the lowest compliance in the farms which may be implicated in the transmission of S. aureus are the lack of handwashing and abnormal milk handling.

The emergence of antibiotic-resistant S. aureus has become a major public health concern, necessitating the discovery of new antimicrobial compounds. Given that the skin microbiome plays a critical role in the host defence against pathogens, the development of therapies that target the interactions between commensal bacteria and pathogens in the skin microbiome offers a promising approach. Here, we report the discovery of two bacteriocins, cerein 7B and cerein B4080, that selectively inhibit S. aureus without affecting S. epidermidis, a commensal bacterium on the skin. Our study revealed that exposure of S. aureus to these bacteriocins resulted in mutations in the walK/R two-component system, leading to a thickening of the cell wall visible by transmission electron microscopy and subsequent decreased sensitivity to vancomycin. Our findings prompt a nuanced discussion of the potential of those bacteriocins for selective targeting of S. aureus on the skin, given the emergence of resistance and co-resistance with vancomycin. The idea put forward implies that by preserving commensal bacteria, selective compounds could limit the emergence of resistance in pathogenic cells by promoting competition with remaining commensal bacteria, ultimately reducing chronical infections and limiting the spread of antibiotic resistance.

The reactive oxygen species (ROS) production by a single neutrophil after stimulation with S. aureus and E. coli was estimated by an electrochemical amperometric method with a high time resolution. This showed significant variability in the response of a single neutrophil to bacterial stimulation, from a “silent cell” to a pronounced response manifested by a series of chronoamperometric spikes. The amount of ROS produced by a single neutrophil under the influence of S. aureus was 5.5-fold greater than that produced under the influence of E. coli. The response of a neutrophil granulocyte population to bacterial stimulation was analyzed using luminol-dependent biochemiluminescence (BCL). The stimulation of neutrophils with S. aureus, as compared to stimulation with E. coli, caused a total response in terms of ROS production that was seven-fold greater in terms of the integral value of the light sum and 13-fold greater in terms of the maximum peak value. The method of ROS detection at the level of a single cell indicated the functional heterogeneity of the neutrophil population, but the specificity of the cellular response to different pathogens was the same at the cellular and population levels.

Microbial infections resistant to conventional antibiotics constitute one of the most important causes of mortality in the world. In some bacterial species, such as Escherichia coli and Staphylococcus aureus pathogens, biofilm formation can favor their antimicrobial resistance. These biofilm-forming bacteria produce a compact and protective matrix, allowing their adherence and colonization to different surfaces, and contributing to resistance, recurrence, and chronicity of the infections. Therefore, different therapeutic alternatives have been investigated to interrupt both cellular communication routes and biofilm formation. Among these, essential oils (EO) from Lippia origanoides thymol-carvacrol II chemotype (LOTC II) plants have demonstrated biological activity against different biofilm-forming pathogenic bacteria. In this work, we determined the effect of LOTC II EO on the expression of genes associated with quorum sensing (QS) communication, biofilm formation, and virulence of E. coli ATCC 25922 and S. aureus ATCC 29213. This EO was found to have high efficacy against biofilm formation, decreasing—by negative regulation—the expression of genes involved in motility (fimH), adherence and cellular aggregation (csgD), and exopolysaccharide production (pgaC) in E. coli. In addition, this effect was also determined in S. aureus where the L. origanoides EO diminished the expression of genes involved in QS communication (agrA), production of exopolysaccharides by PIA/PNG (icaA), synthesis of alpha hemolysin (hla), transcriptional regulators of the production of extracellular toxins (RNA III), QS and biofilm formation transcriptional regulators (sarA) and global regulators of biofilm formation (rbf and aur). Positive regulation was observed on the expression of genes encoding inhibitors of biofilm formation (e.g., sdiA and ariR). These findings suggest that LOTCII EO can affect biological pathways associated with QS communication, biofilm formation, and virulence of E. coli and S. aureus at subinhibitory concentrations and could be a promising candidate as a natural antibacterial alternative to conventional antibiotics.

Multidrug-resistant microorganisms have become a significant public health threat, and traditional antibiotics are becoming ineffective. Photodynamic therapy (PDT) is a promising alternative that utilizes photosensitizers and light to produce Reactive Oxygen Species (ROS) that can kill microorganisms. Zinc phthalocyanine (ZnPc) is a promising photosensitizer due to its strong affinity for encapsulation in nanoemulsions and its antimicrobial properties. In this study, nanoemulsion was prepared using Miglyol 812N, a surfactant, and distilled water to dissolve hydrophobic drugs such as ZnPc. The nanoemulsion was characterized by its particle size, polydispersity index, Transmission Electron Microscope and Zeta potential, and the results showed that it was an efficient nanocarrier system that facilitated the solubilization of hydrophobic drugs in water. The use of ZnPc encapsulated in the nanoemulsion produced through the spontaneous emulsification method resulted in a significant reduction in cell survival percentages of gram-positive Staphylococcus aureus and gram-negative Escherichia coli by 85% and 75%, respectively. This may be attributed to the more complex cell membrane structure of E. coli compared to S. aureus. This demonstrates the potential of nanoemulsion-based PDT as an effective alternative to traditional antibiotics for treating multidrug-resistant microorganisms.

This study integrated four microarray datasets by Robust Rank Aggregation (RRA) method to identify the differentially expressed genes (DEG) in bovine mammary epithelial (BME) cells in response to Escherichia coli and Staphylococcus aureus infection. Furthermore, the GO function and KEGG pathway enrichment analysis of the integrated DEG were performed. Finally, the protein-protein interaction (PPI) network was constructed. A total of 72 integrated DEG were identified from the four datasets. The most significantly enriched terms within the integrated DEG were mainly involved in the immune response. The PPI network of DEG was constructed with 53 nodes. Seventeen genes, which constitute a significant module, were identified as hub genes. Among them, CD40, CXCL6, and NFKBIZ were further screened as the key genes and have the potential to become biomarkers of E. coli and S. aureus mastitis, considering the specificity of biomarkers for diseases. The identified key genes and pathways in this study can assist in the search for biomarkers for mastitis diagnosis and disease resistance breeding.

Intensive Care Units (ICU) usually provide an excellent environment for the selection of pathogens associated with hospital-acquired infections (HAI), leading to increased mortality and hospitalization costs. Methicillin-resistant Staphylococcus pseudintermedius (MRSP) is a major cause of HAI in dogs worldwide, but the risk factors and dynamics of colonization by MRSP are largely unknown. This study aimed to evaluate the risk factors associated with the acquisition of MRSP in dogs admitted to an ICU, and to report the antimicrobial resistance profiles and genetic relatedness of MRSP isolates. Sterile swabs from the nostril, axilla, and rectum were collected daily during the hospitalization of 54 dogs. Samples were subjected to Mannitol Salt Agar, and colonies were identified by MALDI-ToF, polymerase chain reaction (PCR), and sequencing of the rpoB gene. Antimicrobial susceptibility testing and PCR detection of mecA were performed. Staphylococcus spp. was isolated from 94% of the dogs, and the most frequently isolated species was S. pseudintermedius (88.2%). Carriage of multidrug resistant (MDR) staphylococci was observed in 64.4% of the dogs, and approximately 39% had methicillin-resistant Staphylococcus sp. (MRS), of which 21.6% had MRSP and 1.9% had methicillin-resistant S. aureus (MRSA). The acquisition of MRSP during ICU hospitalization was associated with sex (female), age (>7 years), and dogs that had previously been treated with antimicrobials. Animals colonized by MRSP resistant to ≥9 antimicrobial classes had longer hospital stays than those colonized by other MRS strains. Among the 13 MRSP isolates that were subjected to whole-genome sequencing, ten were classified as ST71. A single nucleotide polymorphism (SNP) analysis revealed three clones, including one that was detected in infected dogs outside the ICU. This study indicates novel risk factors associated with colonization by MRSP. The detection of the same MRSP clone causing HAI outside the ICU reinforces the need for improved infection prevention and control practices at veterinary hospitals in general and at the ICU in particular.

Domiati cheese is the most popular type of white soft cheese in Egypt. Staphylococcus aureus is a common microorganism that can easily contaminate Domiati cheese during processing and distribution. Enterotoxigenic S. aureus strains produce staphylococcal enterotoxins (SE) that have been involved in food poisoning outbreaks worldwide. The aim of the present study was to examine the inhibitory effect of yoghourt starter culture and nickel oxide nanoparticles (NiO NPs) on the development of the enterotoxigenic S. aureus together with the enterotoxin production during the manufacturing and storage of Domiati cheese. Fresh cow’s milk was inoculated with S. aureus in a count of six log CFU/mL with the addition of either yoghourt starter culture or NiO Nps. The cytotoxicity of NiO NPs on normal human epithelial cells (HEC) was assessed using the MTT assay. In the current study, the inoculated milk was used for making Domiati cheese and the survival Weibull and log-linear models were fitted to the observed data. The obtained results showed that the mean log count of S. aureus decreased one week earlier by using yoghourt starter culture. Staphylococcal enterotoxin A (SEA) was identified only in the control cheese. Notably, Domiati cheese contained MIC of NiO NPs (35 µg/mL), which resulted in a significant decrease in S. aureus counts since at day 21 of cheese ripening it was not detected (

Antibiotics must be safe and effective for use in both human and veterinary medicine. However, information about the efficacy of different brands of antibiotics commonly used in veterinary practices is lacking in Ethiopia. In this study, we determined the efficacy of three brands of penicillin–streptomycin (Pen&strep, Penstrep, and Pro&strep) by performing antimicrobial susceptibility testing against Staphylococcus aureus isolated from cow milk from dairy farms in the towns of Sebata and Bishoftu, Central Ethiopia. We also assessed the knowledge, attitudes, and practices (KAP) of veterinarians regarding the quality and use of brand antibiotics and the antibiotic utilization practices of dairy farm personnel using a structured questionnaire. Of 43 S. aureus isolated and tested, 33 (77%), 10 (23%), and 1 (2%) were susceptible to brands A, B, and C, respectively. According to the respondents, all of them reported that penstrep is the most prescribed antibiotic in dairy farms (100%), followed by oxytetracycline (78%) and sulfa drugs (52%). All veterinarians perceived that antibiotics imported from Western countries have a higher efficacy than those from Eastern countries, and they preferred brand A to the other brands, witnessing its better clinical outcome. The majority (87%) and a little more than half (53%) of the respondents perceived the overuse of antibiotics in veterinary clinics and dairy farms, respectively. Our study revealed the better efficacy of brand A against S. aureus compared to the other brands. Interestingly, the veterinarians’ perception of and preference toward the use of brand antibiotics agreed with the findings of our antibacterial susceptibility testing. The prudent use of brand A is critically important for sustaining effective treatment, avoiding the risk of antimicrobial resistance, and helping to address animal welfare issues.

Microbial contamination in food and medicine is a situation that closely concerns human health. The fact that the microorganism causing the contamination have antibiotic resistance makes it difficult to eliminate the contamination. Deficiencies such as incorrect use of antibiotics or lack of new antibiotics have caused microorganisms to acquire multiple antibiotic resistance. Methicillin-resistant S. aureus (MRSA) is one of the microorganisms with high antibiotic resistance. The antibiotic resistance mechanisms and biofilm production ability of MRSA has made it more resistant to the environment. In this study, disc diffusion method was used to determine the antimicrobial activities of Heracleum platytaenium and Lavandula spp. essential oils against MRSA, and the results were compared with commercial antibiotics. In addition, the effect of H. platytaenium and Lavandula spp. essential oils on the biofilm produced by MRSA was also investigated. In this study, it was determined that H. platytaenium and Lavandula spp. essential oils have antimicrobial activity against MRSA. It was found that H. platytaenium and Lavandula spp. essential oils have antibiofilm activity against MRSA. H. platytaenium and Lavandula spp essential oils can be alternative natural sources compared to commercial antibiotics in controlling infections from MRSA.

Biomaterial-associated infections (BAIs) are an increasing problem where antibiotic therapies are often ineffective. The design of novel strategies to prevent or combat infection requires a better understanding of how an implanted foreign body prevents the immune system from eradicating surface-colonizing pathogens. The objective of this review is to chart factors resulting in sub-optimal clearance of Staphylococcus aureus bacteria involved in BAIs. To this end, we first describe three categories of bacterial mechanisms to counter the host immune system around foreign bodies: direct interaction with host cells, modulation of intercellular communication, and evasion of the immune system. These mechanisms take place in a time frame that differentiates sterile foreign body reactions, BAIs, and soft tissue infections. In addition, we identify experimental interventions in S. aureus BAI that may impact infectious mechanisms. Most experimental treatments modulate the host response to infection or alter the course of BAI through implant surface modulation. In conclusion, the first week after implantation and infection is crucial for the establishment of an S. aureus biofilm that resists the local immune reaction and antibiotic treatment. Although established and chronic S. aureus BAI is still treatable and manageable, the focus of interventions should lie on this first period.

Biomimetic calcium phosphate (CaP) systems mono-substituted with zinc (Zn2+) and magnesium (Mg2+) ions were prepared from a biogenic source (cuttlefish bone) by wet precipitation method. The results revealed that the as-prepared powders were composed of calcium-deficient carbonated hydroxyapatite (HAp), octacalcium phosphate (OCP), and amorphous calcium phosphate (ACP), while the heat-treated powders consisted of HAp, α-tricalcium phosphate (α-TCP), and β-tricalcium phosphate (β-TCP). In addition to Zn2+ and Mg2+ ions, the presence of CO32−, Sr2+ and Na + ions was detected with elemental analysis, which can be attributed to the use of cuttlefish bone as a natural precursor of Ca2+ ions. The data obtained by XRD study demonstrated the decrease in lattice parameters in the OCP and β-TCP phases for Zn-substitution and Mg-substitution in the HAp, OCP, and β-TCP phases. Zn2+ occupies the Ca(1,3,4,6,7,8) sites in OCP and Ca(1,2,3,4) sites in β-TCP, while Mg2+ occupies the Ca(2) sites in HAp and the Ca(4,5) sites in β-TCP. Phase transformation study under simulated physiological conditions for 7 days showed the transformation of OCP and ACP into the thermodynamically more stable HAp. Characterization of the zeta-potential showed positively charged populations for all prepared CaP powders, while all samples showed high bovine serum albumin adsorption capacity. The culture of human embryonic kidney cells showed that the prepared CaPs are non-cytotoxic and that viability of the cells increases during the culture period. All powders obtained showed antibacterial activity towards Gram-negative Escherichia coli and low antibacterial effect against Gram-positive Staphylococcus aureus, as determined by viability analysis during 48 h. Inhibition zone analysis and observation of the morphology after 24 h showed no antibacterial properties. publishedVersion

With the advancement in reusable rocket propulsion technology, space tourist trips into outer space are now becoming a possibility at a cost-effective rate. As such, astronauts will face a host of health-related challenges, particularly on long-duration space missions where maintaining a balanced healthy microbiome is going to be vital for human survival in space exploration as well as mission success. The human microbiome involves a whole list of micro-organisms that reside in and on the human host, and plays an integral role in keeping the human host healthy. However, imbalances in the microbiome have been directly linked to many human diseases. Research findings have clearly shown that the outer space environment can directly affect the normal microbiome of astronauts when the astronaut is exposed to the microgravity environment. In this study, we show that the simulation of microgravity on earth can mimic the outer space microgravity environment. Staphylococus aureus (S. aureus) was chosen for this study as it is an opportunistic pathogen, which is part of the normal human skin microflora and the nasal passages. This study’s results show that S. aureus proliferation was significantly increased under a microgravity environment compared to Earth’s gravity conditions, which complements previous work performed on bacteria in the outer space environment in the International Space Station (ISS). This demonstrates that this technology can be utilised here on Earth to mimic the outer space environment and to study challenging health-related questions. This in return saves us the cost on conducting experiments in the ISS and can help advance knowledge at a faster rate and produce countermeasures to mitigate the negative side effects of the hostile outer space environment on humans.

LF3872 was isolated from the milk of a healthy lactating and breastfeeding woman. Earlier, the genome of LF3872 was sequenced, and a gene encoding unique bacteriocin was discovered. We have shown here that the LF3872 strain produces a novel thermolabile class III bacteriolysin (BLF3872), exhibiting antimicrobial activity against antibiotic-resistant Staphylococcus aureus strains. Sequence analysis revealed the two-domain structural (lysozyme-like domain and peptidase M23 domain) organization of BLF3872. At least 25% residues of this protein are expected to be intrinsically disordered. Furthermore, BLF3872 is predicted to have a very high liquid-liquid phase separation. According to the electron microscopy data, the bacterial cells of LF3872 strain form co-aggregates with the S. aureus 8325-4 bacterial cells. LF3872 produced bacteriolysin BLF3872 that lyses the cells of the S. aureus 8325-4 mastitis-inducing strain. The sensitivity of the antibiotic-resistant S. aureus collection strains and freshly isolated antibiotic-resistant strains was tested using samples from women with lactation mastitis; the human nasopharynx and oral cavity; the oropharynx of pigs; and the cows with a diagnosis of clinical mastitis sensitive to the lytic action of the LF3872 strain producing BLF3872. The co-cultivation of LF3872 strain with various antibiotic-resistant S. aureus strains for 24 h reduced the level of living cells of these pathogens by six log. The LF3872 strain was found to be able to co-aggregate with all studied S. aureus strains. The cell-free culture supernatant of LF3872 (CSLF3872) induced S. aureus cell damage and ATP leakage. The effectiveness of the bacteriolytic action of LF3872 strain did not depend on the origin of the S. aureus strains. The results reported here are important for the creation of new effective drugs against antibiotic-resistant strains of S. aureus circulating in humans and animals.

Implant infections caused by Staphylococcus aureus are difficult to treat due to biofilm formation, which complicates surgical and antibiotic treatment. We introduce an alternative approach using monoclonal antibodies (mAbs) targeting S. aureus and provide evidence of the specificity and biodistribution of S.-aureus-targeting antibodies in a mouse implant infection model. The monoclonal antibody 4497-IgG1 targeting wall teichoic acid in S. aureus was labeled with indium-111 using CHX-A”-DTPA as a chelator. Single Photon Emission Computed Tomography/computed tomographyscans were performed at 24, 72 and 120 h after administration of the 111In-4497 mAb in Balb/cAnNCrl mice with a subcutaneous implant that was pre-colonized with S. aureus biofilm. The biodistribution of this labelled antibody over various organs was visualized and quantified using SPECT/CT imaging, and was compared to the uptake at the target tissue with the implanted infection. Uptake of the 111In-4497 mAbs at the infected implant gradually increased from 8.34 %ID/cm3 at 24 h to 9.22 %ID/cm3 at 120 h. Uptake at the heart/blood pool decreased over time from 11.60 to 7.58 %ID/cm3, whereas the uptake in the other organs decreased from 7.26 to less than 4.66 %ID/cm3 at 120 h. The effective half-life of 111In-4497 mAbs was determined to be 59 h. In conclusion, 111In-4497 mAbs were found to specifically detect S. aureus and its biofilm with excellent and prolonged accumulation at the site of the colonized implant. Therefore, it has the potential to serve as a drug delivery system for the diagnostic and bactericidal treatment of biofilm.

Staphylococcus aureus is a Gram-positive opportunistic human pathogen responsible for severe infections and thousands of deaths annually, mostly due to its multidrug-resistant (MDR) variants. The cell membrane has emerged as a promising new therapeutic target, and lipophilic molecules, such as biosurfactants, are currently being utilized. Herein, we evaluated the antimicrobial activity of a rhamnolipids mixture produced by the Antarctic marine bacterium Pseudomonas gessardii M15. We demonstrated that our mixture has bactericidal activity in the range of 12.5–50 µg/mL against a panel of clinical MDR isolates of S. aureus, and that the mixture eradicated the bacterial population in 30 min at MIC value, and in 5 min after doubling the concentration. We also tested abilities of RLs to interfere with biofilm at different stages and determined that RLs can penetrate biofilm and kill the bacteria at sub-MICs values. The mixture was then used to functionalize a cotton swab to evaluate the prevention of S. aureus proliferation. We showed that by using 8 µg of rhamnolipids per swab, the entire bacterial load is eradicated, and just 0.5 µg is sufficient to reduce the growth by 99.99%. Our results strongly indicate the possibility of using this mixture as an additive for wound dressings for chronic wounds.

The severity of infectious diseases associated with the resistance of microorganisms to drugs highlights the importance of investigating bioactive compounds with antimicrobial potential. Therefore, nineteen synthetic cinnamides and cinnamates having a cinnamoyl nucleus were prepared and submitted for the evaluation of antimicrobial activity against pathogenic fungi and bacteria in this study. To determine the minimum inhibitory concentration (MIC) of the compounds, possible mechanisms of antifungal action, and synergistic effects, microdilution testing in broth was used. The structures of the synthesized products were characterized with FTIR spectroscopy, 1 H-NMR, 13 C-NMR, and HRMS. Derivative 6 presented the best antifungal profile, suggesting that the presence of the butyl substituent potentiates its biological response (MIC = 626.62 μM), followed by compound 4 (672.83 μM) and compound 3 (726.36 μM). All three compounds were fungicidal, with MFC/MIC ≤ 4. For mechanism of action, compounds 4 and 6 directly interacted with the ergosterol present in the fungal plasmatic membrane and with the cell wall. Compound 18 presented the best antibacterial profile (MIC = 458.15 μM), followed by compound 9 (550.96 μM) and compound 6 (626.62 μM), which suggested that the presence of an isopropyl group is important for antibacterial activity. The compounds were bactericidal, with MBC/MIC ≤ 4. Association tests were performed using the Checkerboard method to evaluate potential synergistic effects with nystatin (fungi) and amoxicillin (bacteria). Derivatives 6 and 18 presented additive effects. Molecular docking simulations suggested that the most likely targets of compound 6 in C. albicans were caHOS2 and caRPD3, while the most likely target of compound 18 in S. aureus was saFABH. Our results suggest that these compounds could be used as prototypes to obtain new antimicrobial drugs.

Under normal physiological condition the body needs to fight bacterial infection, clear old dead or dying cells as well as regenerate new ones. Phagocytosis is the immunological process required for cells to digest and destroy particulates thereby maintaining a systemic homeostasis. Phagocytosis involves four steps of recognition, engulfment, formation of phagosome, degradation and elimination. In the nervous system, the phagocytes are the glial cells which support the system framework, primarily microglia. Spinal cord injury is an irreparable nervous system injury and restoration of function is very difficult. One strategy which could aid repair and regeneration is to enhance the phagocytic process thereby removing cell debris and bacteria from the injury site. Glial cells are involved in phagocytosis and clearing the spinal cord injury area. Understanding this process may improve strategies to develop therapy, particularly those that involve cell transplantation such as peripheral nerve glia. Within the nervous system, the main phagocytic glia, which has been studied, in the central nervous system (CNS) are astrocytes and microglia, and in the peripheral nervous system (PNS), the main glia are Schwann cells for most nerves, with olfactory ensheathing cells (OECs) in the olfactory nerve. In this study, my first objective was to compare the CNS and PNS cells like astrocytes, microglia, OECs and trigeminal Schwann cells (TgSCs) for their antimicrobial response to bacterial infection (S. aureus). Results showed live bacteria could be isolated from all glia after 24 h in culture, and microglia, OECs and TgSCs exhibited better protection against intracellular S. aureus survival than astrocytes. All glial types responded to the bacteria by cytokine secretion, but overall, OECs secreted the lowest level of cytokines. Debris clearance is crucial for neural regeneration and OECs have the ability to phagocytose both bacteria and cell debris. OECs and SCs are being considered as cell transplantation therapies in spinal cord injury for the purpose of repairing the damaged nervous system. Thus, understanding the genetic expression in between OECs and SCs during the process of phagocytosis of bacteria (S. aureus) and axonal debris is essential. Results showed OECs responded to S. aureus with protein modification and phosphorus metabolic processes involved with immune response, and leukocyte mediated immunity signalling mechanisms for bacterial engulfment. SCs responded to cell debris with pathways associated with actin filament-based processes, cytoskeleton organization, and FC gamma receptor dependent phagocytosis. These findings demonstrate the differences between OECs and SCs during phagocytic responses to bacteria and cell debris. Overall, OECs expressed a low gene expression profile compared to SCs. Discovering novel compounds that can stimulate OECs to phagocytose bacteria and cell debris more efficiently may improve the therapeutic potential of the cells. Potentially, if OECs could be pre-stimulated with a drug to enhance OEC phagocytosis, that could be useful in spinal cord injury regeneration. Therefore to identify compounds that would enhance the phagocytosis of glial cells, drug discovery assays were performed. Following a preliminary compound screening, a synthetic compound and a natural compound was identified. For a third compound, a FDA approved drug was selected to test their effects on glial cells. As the process and analyses, required to identify compounds, that stimulate glial cell phagocytic activity has not been previously established, development and optimization of a protocol for phagocytosis detection was performed. Phagocytosis measurement in glial cells based on live imaging and fixed widefield imaging was performed to make a replicable drug discovery testing method which could be used on cell lines and primary cells both. Using this method results like cytotoxicity, morphological changes and phagocytosis of various targets can be reliably performed. Testing the compounds with the protocol, demonstrated that significant stimulation of phagocytosis activity could be detected. All three compounds tested showed positive phagocytosis increase on cell lines. The synthetic compound showed positive increase in phagocytosis on primary OECs and TgSCs but not in astrocytes and microglia for S. aureus pHrodo BioParticles. Testing further, using the synthetic compound, in the presence of bacterial stimulus, showed no significant upregulation in cytokines but some positive upregulation in phagocytotic genes, in the compound stimulated wells against controls. The natural compound showed increase in phagocytosis only in microglia but not in other glial cells (OECs, TgSCs and astrocytes). The FDA compound Liraglutide showed significant increase in phagocytosis in all glial cells (astrocytes, microglia, OECs and TgSCs). Testing the synthetic compound on the phagocytosis of Beta (β) amyloid peptide, in OECs, astrocytes and microglia, showed an increase in peptide uptake in compound stimulated OECs as compared to non-stimulated ones. Astrocyte and microglia did not show any difference. In conclusion, this thesis gives us an understanding of the difference between CNS and PNS phagocytosis. While the different glial cells share many properties, OECs exhibit several characteristics which make them favourable candidates for transplantation therapies. Compound testing revealed that phagocytic activity can be stimulated and opens up avenues for identification of compounds that could be used to enhance therapeutic activity of glial cells in SCI and possibly in Alzheimer’s diseases research.

Biofilms confer several advantages to the organisms associated with them, such as increased resistances to antibacterial and antifungal compounds compared to free living cells. Compared to monomicrobial biofilms involving a single microorganism, biofilms composed of microorganisms affiliated to bacterial and fungal kingdoms are predominant in nature. Despite the predominance of polymicrobial biofilms, and more so mixed polymicrobial biofilms, they are rarely studied. The objective of the current study is to evaluate the potential of ocular bacteria and a filamentous fungus to form monomicrobial and mixed polymicrobial biofilms on synthetic and natural substrates and to monitor their response to antibiotics. In this sense, we demonstrated that the ocular pathogens Staphylococcus aureus, S. epidermidis, and Fusarium solani form monomicrobial and mixed polymicrobial biofilms both on tissue culture polystyrene plates and on ex vivo human corneas from cadavers using confocal microscopy and scanning electron microscopy. Additionally, the mixed polymicrobial biofilms involving the above ocular bacteria and a filamentous fungus were less susceptible to different antibacterials and antifungals in relation to the corresponding control planktonic cells. Further, the MICs to the screened antibacterials and antifungals in polymicrobial biofilms involving a bacterium or a fungus was either increased, decreased, or unchanged compared to the corresponding individual bacterial or fungal biofilm. The results would be useful to the ophthalmologist to plan effective treatment regimens for the eye since these are common pathogens of the eye causing keratitis, endophthalmitis, conjunctivitis, etc.

Reference genes are frequently used for the normalization of quantitative reverse transcriptase PCR (qRTPCR) data in gene expression studies. Staphylococcus aureus is one of the most common causes of biofilm-related infections. Savirin and ticagrelor show in vitro as well as in vivo antibiofilm activity against S. aureus. The main aim of this study was to identify the most stably expressed reference genes to study the effect of these molecules on genes in a strong biofilm producing S. aureus isolate isolated from biofilm-related infection. Quantitative real-time PCR was performed by using relative quantification method. Four different algorithms, delta Ct, normfinder, bestkeeper, and genorm, followed by a comprehensive analysis was used to identify the most stable reference genes from a list of sixteen different candidate reference genes. All four algorithms reported different results, with some comparable findings among some methods. In the comprehensive analysis of the results of all the algorithms used, the most stable reference genes found were spa, rpoD, and pyk for savirin treatment experiment and gapdH, gyrA, and gmk for ticagrelor treatment experiment. The optimal number of reference genes required was two for both the experimental conditions. Despite having some drawbacks, each algorithm can reliably determine an appropriate reference gene independently. However, based on consensus ranking and the required optimal number of reference genes reported, spa and rpoD were the most appropriate reference genes for savirin treatment experiment, and gapdH and gyrA were most appropriate for ticagrelor treatment experiment. This study provides baseline data on reference genes to study the effect of savirin or ticagrelor treatment on the expression of potential reference genes in S. aureus. We recommend prior re-validation of reference genes on a case-by-case basis before they can be used.

Abattoir workers have been identified as high-risk for livestock-associated Staphylococcus aureus carriage. This study investigated S. aureus carriage in abattoir workers in Western Kenya. Nasal swabs were collected once from participants between February-November 2012. S. aureus was isolated using bacterial culture and antibiotic susceptibility testing performed using the VITEK 2 instrument and disc diffusion methods. Isolates underwent whole genome sequencing and Multi Locus Sequence Types were derived from these data. S. aureus (n = 126) was isolated from 118/737 (16.0%) participants. Carriage was higher in HIV-positive (24/89, 27.0%) than HIV–negative participants (94/648, 14.5%; p = 0.003). There were 23 sequence types (STs) identified, and half of the isolates were ST152 (34.1%) or ST8 (15.1%). Many isolates carried the Panton-Valentine leucocidin toxin gene (42.9%). Only three isolates were methicillin resistant S. aureus (MRSA) (3/126, 2.4%) and the prevalence of MRSA carriage was 0.4% (3/737). All MRSA were ST88. Isolates from HIV-positive participants (37.0%) were more frequently resistant to sulfamethoxazole/trimethoprim compared to isolates from HIV-negative participants (6.1%; p < 0.001). Similarly, trimethoprim resistance genes were more frequently detected in isolates from HIV-positive (81.5%) compared to HIV-negative participants (60.6%; p = 0.044). S. aureus in abattoir workers were representative of major sequence types in Africa, with a high proportion being toxigenic isolates. HIV-positive individuals were more frequently colonized by antimicrobial resistant S. aureus which may be explained by prophylactic antimicrobial use.

Microbial infections are by no means a health problem from a past era due to the increasing antimicrobial resistance of infectious strains. Medicine is in constant need of new drugs and, recently, plant products have had a deserved renaissance and garnered scientific recognition. The aim of this work was to assess the antimicrobial activity of ten active ingredients from four Hypericum species growing in Bulgaria, as well as to obtain preliminary data on the phytochemical composition of the most promising samples. Extracts and fractions from H. rochelii Griseb. ex Schenk, H. hirsutum L., H. barbatum Jacq. and H. rumeliacum Boiss. obtained with conventional or supercritical CO2 extraction were tested on a panel of pathogenic microorganisms using broth microdilution, agar plates, dehydrogenase activity and biofilm assays. The panel of samples showed from weak to extraordinary antibacterial effects. Three of them (from H. rochelii and H. hirsutum) had minimum inhibitory concentrations as low as 0.625–78 mg/L and minimum bactericidal concentrations of 19.5–625 mg/L against Staphylococcus aureus and other Gram-positive bacteria. These values placed these samples among the best antibacterial extracts from the Hypericum genus. Some of the agents also demonstrated very high antibiofilm activity against methicillin-resistant S. aureus. Ultra-high-performance liquid chromatography–high-resolution mass spectrometry revealed the three most potent samples as rich sources of biologically active phloroglucinols. They were shown to be good drug or nutraceutical candidates, presumably without some of the side effects of conventional antibiotics.

Macrolides inhibit biofilm formation in several Gram-negative, intrinsically-resistant bacterial species. However, the effect of macrolides upon biofilm formation by susceptible Gram-positive bacteria has been much less explored as such concentrations also inhibit cell growth. To circumvent this problem, the effect of macrolides (erythromycin, clarithromycin and azithromycin) at 0.5–2 µg/mL, upon biofilm formation, was explored on macrolide-resistant Staphylococcus aureus isolates, using the crystal violet assay with 96-well plates. Early (4 h) biofilm formation by strains having constitutive target-modification resistance was consistently induced by all macrolides but not in azithromycin-treated cells in longer (8 and 12 h) incubation. In inducible-resistance isolates, early biofilm formation was enhanced by some macrolide treatments, compared to similar cell growth in the absence of antibiotics; but the typical decay of biofilms at longer incubation appeared prematurely in macrolide-treated cultures. Biofilm formation in an efflux-mediated resistant isolate was not affected by macrolides. These results indicate that macrolides induce the formation of biofilm by resistant S. aureus isolates, especially during the early stages. This suggests that the empirical use of macrolides against infections caused by resistant S. aureus strains could not only result in clinical failure but even in the enhancement of biofilms, making further treatment difficult.

a systematic review on the effect of biocides on antibiotic tolerance in staphylococcus aureus, and whether the stringent response is induced in this development of tolerance.

Presence of pathogens on the cellphones and their accessories poses a significant risk for public health. This study aimed to determine the biofilm-forming capability of S. aureus and E. coli on pieces made from a different commercially available cell phone and aadditionally to test the effectiveness of the most common commercially available sanitizers. Therefore, bacterial biofilm biomasses were quantitatively determined on cellphone covers using crystal violet assay in the presence and absence of common sanitizers. This study revealed that S. aureus and E. coli could form biofilms on the surfaces of all cellphones covers. Additionally, the sanitizers that contain sodium hypochlorite 5.25% and those composed of 38.9% ethanol and 0.05% dodecyl dimethyl ammonium chloride showed the highest log reduction in the number of viable cells after 5 minutes of exposure against biofilms formed by both E. coli and S. aureus compared to other tested sanitizers (chloroxylenol 4.8%, 2-propanol 64%, and ethanol 70%). Moreover, 4.8% chloroxylenol and 70% ethanol-based sanitizers showed log reductions significantly higher than 2-propanol-based ones. In conclusion, cellphone covers were shown to be suitable surfaces for microbial biofilm formation produced by S. aureus and E. coli. The antimicrobial activity of commercially available sanitizers against these bacterial biofilms was variable, with sodium hypochlorite and ethanol/dodecyl dimethyl ammonium chloride sanitizer being the most effective.

Refereed/Peer-reviewed The intracellular survival of bacteria is a significant challenge in the fight against antimicrobial resistance. Currently available antibiotics suffer from limited penetration across host cell membranes, resulting in suboptimal treatment against the internalised bacteria. Liquid crystalline nanoparticles (LCNP) are gaining significant research interest in promoting the cellular uptake of therapeutics due to their fusogenic properties; however, they have not been reported for targeting intracellular bacteria. Herein, the cellular internalisation of LCNPs in RAW 264.7 macrophages and A549 epithelial cells was investigated and optimized through the incorporation of a cationic lipid, dimethyldioctadecylammonium bromide (DDAB). LCNPs displayed a honeycomb-like structure, while the inclusion of DDAB resulted into an onion-like organisation with larger internal pores. Cationic LCNPs enhanced the cellular uptake in both cells, reaching up to ∼ 90% uptake in cells. Further, LCNPs were encapsulated with tobramycin or vancomycin to improve their activity against intracellular gram-negative, Pseudomonas aeruginosa (P. aeruginosa) and gram-positive, Staphylococcus aureus (S. aureus) bacteria. The enhanced cellular uptake of cationic LCNP resulted in significant reduction of intracellular bacterial load (up to 90% reduction), compared to antibiotic dosed in its free form; with reduced performance observed for epithelial cells infected with S. aureus. Specifically engineered LCNP can re-sensitise antibiotics against both intracellular Gram positive and negative bacteria in diverse cell lines.

Silver nanoparticles (AgNPs), which have recently gained attention due to their antimicrobial activity, can also be produced by green synthesis. The aims of this study were to (i) characterise green synthesized AgNPs using microwave-assisted aqueous extracts of Galium aparine (G-AgNPs) and Helichrysum arenarium (H-AgNPs) and (ii) investigate the combined antimicrobial effects of the G- and H-AgNPs in different ratios. Nanoparticle formation and reactions were determined with UV-Vis spectroscopy. The G-AgNPs were 52.0±10.9 nm in size, with a 0.285±0.034 polydispersity index (PDI), and a -17.9±0.9 mV zeta potential. For H-AgNPs these characteristics were 23.9±1.0 nm, 0.280±0.032, and -21.3±2.7 mV, respectively. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) confirmed that the particles were monodisperse and spherical. The Fourier transform-infrared spectroscopy (FT-IR) results showed the presence of reducing agents that stabilised the AgNPs. Three different nanoformulations (NF-1, NF-2, and NF-3) were prepared by combining these two synthesised nanoparticles in different ratios and their antimicrobial activity was tested against E. coli, S. aureus, C. albicans, and A. flavus. Our study is the first to show that combining AgNPs from two different biological sources can produce effective nanoformulations with improved antibacterial activity against E. coli and S. aureus. These nanoformulations showed lower minimum inhibitory concentrations (31.25 μg/mL against E. coli with all NFs; 62.5 μg/mL for NF-1 and 125 μg/mL for NF-2/3 against S. aureus) than G-AgNPs (62.5 μg/mL for E. coli) or H-AgNPs (125 μg/mL for S. aureus) alone. Their high combined inhibitory effect against E. coli (NF-1–3) was synergistic and against S. aureus (NF-2 and NF-3) potentially additive. Considering such promising results, we believe our study provides some direction for new research and strategies in antimicrobial therapeutics., Srebrne se nanočestice (AgNP), koje su već neko vrijeme u središtu pažnje zbog svojih antimikrobnih svojstava, mogu proizvoditi i zelenom sintezom. Cilj je ovog istraživanja bio (i) opisati (karakterizirati) zelenu sintezu različitih AgNP-a pomoću vodenih ekstrakata čekinjaste broćike (Galium aparine) (G-AgNPs) i pješčarskoga smilja (Helichrysum arenarium) (H-AgNPs), dobivenih metodom mikrovalne ekstrakcije, te (ii) utvrditi antimikrobno djelovanje kombinacije tih dvaju nanosustava u različitim omjerima. Oblikovanje nanočestica i kemijske reakcije utvrđene su pomoću UV-Vis spektroskopije. Veličina G-AgNP-a bila je 52,0±10,9 nm, njihov polidisperzivni indeks (PDI) 0,285±0,034, a zeta potencijal -17,9±0,9 mV. Osobine H-AgNP-a bile su sljedeće: veličina 23,9±1,0 nm, PDI 0,280±0,032, a zeta potencijal -21,3±2,7 mV. Mikroskopijom atomskih sila (engl. atomic force microscopy, krat. AFM) i pretražnom elektronskom mikroskopijom (engl. scanning electron microscopy, krat. SEM) potvrđeno je da su čestice monodisperzivne i sferične. Rezultati infracrvene spektroskopije s Fourierovom transformacijom (engl. Fourier transform-infrared spectroscopy, krat. FT-IR) potvrdili su prisutnost reduktivnih agenasa koji su stabilizirali srebrne nanočestice. Zatim su pripremljene tri formulacije nanočestica (NF-1, NF-2 i NF-3) kombinacijom sintetiziranih nanočestica u različitim omjerima, a njihova antimikrobna djelotvornost testirana je na mikroorganizmima E. coli, S. aureus, C. albicans i A. flavus. Naše je istraživanje prvo koje dokazuje da kombinacija srebrnih nanočestica dobivenih iz dvaju bioloških izvora može biti djelotvorna te da ima poboljšano antibakterijsko djelovanje protiv E. coli i S. aureus u odnosu na zasebne nanosustave. Minimalna inhibicijska koncentracija kombinacija iznosila je 31,25 μg/mL za E. coli u svim nanoformulacijama te 62,5 μg/mL za S. aureus s NF-1, odnosno 125 μg/mL s NF-2 i NF-3, a minimalne inhibicijske koncentracije G-AgNP-a odnosno H-AgNP-a zasebno su iznosile 62,5 μg/mL za E. coli (G-AgNP), odnosno 125 μg/mL za S. aureus (H-AgNP). To kombinirano antibakterijsko djelovanje protiv E. coli bilo je sinergijsko, a protiv S. aureus naizgled aditivno. S obzirom na ovako obećavajuće rezultate, smatramo da naše istraživanje daje smjer za razvoj novih strategija u antibakterijskom liječenju.

Domiati cheese is the most popular type of white soft cheese in Egypt. Staphylococcus aureus is a common microorganism that can easily contaminate Domiati cheese during processing and distribution. Enterotoxigenic S. aureus strains produce staphylococcal enterotoxins (SE) that have been involved in food poisoning outbreaks worldwide. The aim of the present study was to examine the inhibitory effect of yoghourt starter culture and nickel oxide nanoparticles (NiO NPs) on the development of the enterotoxigenic S. aureus together with the enterotoxin production during the manufacturing and storage of Domiati cheese. Fresh cow’s milk was inoculated with S. aureus in a count of six log CFU/mL with the addition of either yoghourt starter culture or NiO Nps. The cytotoxicity of NiO NPs on normal human epithelial cells (HEC) was assessed using the MTT assay. In the current study, the inoculated milk was used for making Domiati cheese and the survival Weibull and log-linear models were fitted to the observed data. The obtained results showed that the mean log count of S. aureus decreased one week earlier by using yoghourt starter culture. Staphylococcal enterotoxin A (SEA) was identified only in the control cheese. Notably, Domiati cheese contained MIC of NiO NPs (35 µg/mL), which resulted in a significant decrease in S. aureus counts since at day 21 of cheese ripening it was not detected (

Background: Chronic wounds, such as vascular-, pressure-, and diabetic ulcers, are a growing public health problem, with an escalating medical and socioeconomic impact. These stubborn wounds are often stuck in the inflammatory phase of wound healing, and thus develop prolonged and/or excessive inflam-mation, local tissue hypoxia, persistent polymicrobial infections, and alkalinisation of the wound pH. Therefore, the continuous development of appropriate preclinical wound models, reflecting above-mentioned conditions and pathogenesis found in real chronic wounds, is vital, as they serve as the founda-tion on which novel treatments and diagnostics are created. In an effort to fulfil these requirements, Chen et al. (2021) developed the in vitro layered chronic wound biofilm (CWB) model, which the experimental work of this thesis has been based upon.Methods/Results: In the present thesis, three new strains of clinical P. aeruginosa (PA 209, 286, and 288) and S. aureus (SAU 590, 878, and 883), isolated from chronic venous leg ulcers, in addition to the strains used in the original article (PA 14 and SAU DSM), were established in a slightly updated version of the CWB model. This was done to evaluate the performance of the CWB model when different, clinically rele-vant bacterial strains were applied, as preclinical wound models that mimic the environment and biofilm formation found in in vivo wounds are of rising importance. The capability and in vivo accuracy of the CWB model was assessed through biofilm viability counts, pH measurements, confocal microscopy, and treatment susceptibility testing against the commercially used silver antiseptic, the Physiotulle® Ag band-age, and/or a pH 4 citric acid buffer.In the first part of the thesis, each P. aeruginosa and S. aureus strain were established as single species in the CWB model and incubated at 33 ℃ for 96 hours, where stable and comparable growth was obtained for all strains. The stains then moved on to the second part of the thesis, where they were combined in pairs, based on the patient they were isolated from or at random, and tested under the same conditions as in the single species models. Microscopy of the double species models confirmed the presence of both mixed- and separate microcolonies, and that they had migrated and spread throughout both the dermis and fat layer of the CWB model. Furthermore, pH measurements confirmed that all P. aeruginosa and S. aureus pairs ob-tained a more alkaline pH over time, mimicking microenvironment found in chronic wounds. The viability counts showed that only the two pairs combined at random; PA 14 + SAU DSM and PA 209 + SAU 590, obtained stable growth, as the P. aeruginosa strain dominated the S. aureus strain in the PA 286 + SAU 878 and PA 288 + SAU 883 pairs. Lastly, it was found that out of the two treated P. aeruginosa and S. aureus pairs, the treatments only had a negative effect on the viability of the new clinical strains, PA 209 + SAU 590, and not the lab strains, PA 14 + SAU DSM, which in some cases actually showed increased growth. Conclusion: Although further studies are necessary to support the results obtained through this thesis, it can be concluded, that this version of the CWB model is a credible and clinically relevant chronic wound model, which undoubtedly could provide an important foundation for future prospective studies.

This study aims to assess the occurrence of Staphylococcus aureus in chicken fillets and to control its growth using various lyophilized seaweed extracts (i.e., Halimeda opuntia (HO), Actinotrichia fragilis, and Turbinaria turbinata) by an agar disk diffusion assay in vitro. Results showed that prevalence of S. aureus in breast and thigh samples reached of 92% and 84%, respectively. Lyophilized HO extract was the only seaweed that showed the antibacterial activity against S aureus with a significant difference at p < 0.05. The minimum inhibitory concentration (MIC) of HO extract was 1.5%, with an inhibition zone of 8.16 ± 0.73 mm. Regarding 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity, IC50 was recorded at 55.36 μg/mL, whereas cytotoxic IC50 of the lyophilized HO extract on peripheral blood mononuclear cells (PBMCs) was 33.7 µg/mL; a higher IC50 of HO extracts permits their use as a safe food additive in meat products. Moreover, total phenolic compounds and total flavonoids compounds recorded 20.36 ± 0.092 and 16.59 ± 0.029 mg/mL, respectively. HPLC analyses of phenolic compounds profiles exhibited many bioactive substances and the higher ratio was daidzein with 10.84 ± 0.005 µg/mL and followed by gallic acid with a value of 4.06 ± 0.006 µg/mL. In a challenge study, chicken fillet (CHF) experimentally inoculated with S. aureus (ST) and treated with the lyophilized HO algal extract at 4% and 6% (CHF/ST/HO) showed a complete reduction of S. aureus count on the 6th and 4th days in chicken fillet stored at 4 °C, respectively. Moreover, CHF/ST/HO at 4% and 6% of HO extract enhanced the sensory attributes of grilled un-inoculated chicken fillet. Thus, lyophilized HO extracts are promising antibacterial and antioxidant candidates in the chicken meat industry.

Bu çalışmada anabilim dalı kültür koleksiyonunda bulunan subklinik mastitisli sığır sütlerinden izole edilen 140 adetstafilokok izolatından Staphylococcus aureus izolatlarının moleküler identifikasyonu ve bazı önemli virülens genlerinin tespitiamaçlandı. Bu amaçla 140 stafilokok izolatı termonükleaz (nuc) gen varlığı yönünden PZR ile incelendi. nuc geni (279 bp)tespit edilen 42 izolat S. aureus olarak identifiye edildi. Ayrıca izolatlarda lökotoksin geni (pvl), stafilokokal klasikenterotoksin genleri (sea, seb, sec), eksfolyatif toksin genleri (eta, etb), hemolizin genleri (hla, hlb), adezin faktör genleri(fnbA, fnbB, clfa) ve toksik şok sendrom toksin geni (tst) olmak üzere 12 farklı virülens geninin varlığı 3 farklı multipleks PZRkullanılarak araştırıldı. İzolatların 30 (%71.4)’u clfa, 24 (%57.1)’ü hla, 14 (%33.3)’ü hlb, 10 (%23.8)’u fnbB, 6 (%14.2)’sıfnbA, 6(%14.2)’sıetb, 5 (%11.9)’i sec, 5 (%11.9)’i tst, 3 (%7.1)’ü sea, 2 (%4.7)’si pvl ve 1 (%2.3)’i eta geni açısından pozitif bulundu.İzolatların hiçbirinde seb geni saptanamadı. İzolatların38’inde bir ya da daha fazla virülens geni, 29’unda ise iki ya da dahafazla virülens geni belirlendi. 4 izolatta ise incelenen virülens genlerin hiçbiri saptanamadı. İncelenen izolatlarda en fazla tespit edilen virülens genlerin clfa ve hla olduğu görüldü. Sonuç olarak sınırlı dahi olsa sığır mastitislerinin patogenezinde roloynayan virülens gen patternleri ortaya konuldu. Çalışma sonuçlarının sığır mastitislerinin etiyolojisinde önemli rol oynayan S. aureus’a ait virülens faktörlerinin karakterizasyon çalışmalarına katkı sağlayacağı kanaatine varıldı. This study aimed to determine the molecular identification of Staphylococcus aureus isolates and some importantvirulence genes from 140 staphylococci samples isolated from cow milk with mastitis in the culture collection of thedepartment. For this purpose, the presence of the thermonuclease (nuc) gene in 140 S. aureus isolates was examined byPCR. Forty‐two isolates that were positive for the nuc gene (279 bp) were identified as S. aureus. In addition, the isolateswere examined for the presence of 12 different virulence genes, including leukotoxin gene (pvl), staphylococcal classicalenterotoxin genes (sea, seb, sec), exfoliative toxin genes (eta, etb), hemolysin genes (hla, hlb), adhesin factor genes (fnbA,fnbB, clfa), and toxic shock syndrome toxin gene (tst), using three different multiplex PCR. Of the isolates were found to bepositive 30 (71.4%) for clfa, 24 (57.1%) hla, 14 (33.3%) hlb, 10 (23.8%) fnbB, 6 (14.2%) fnbA, 6 (14.2%) etb, 5 (11.9%) sec, 5(11.9%) tst, 3 (7.1%) sea, 2 (4.7%) pvl, and 1 (2.3%) eta genes. The seb gene was not detected in any of the isolates. At thesame time one or more virulence genes were determined in 38 of 42 isolates, two or more virulence genes in 29 of theisolates. None of the virulence genes examined in 4 isolates could be detected. It was seen that the mostdetected virulencegenes in the analyzed isolates were clfa and hla. As a result, virulence gene patterns that play a role in the pathogenesis ofbovine mastitis, even if limited, were revealed. It was concluded that the results would contribute to the characterizationstudies of virulence factors belonging to S. aureus, which play an important role in the etiology of bovine mastitis.

Biomaterial-associated infections (BAIs) are an increasing problem where antibiotic therapies are often ineffective. The design of novel strategies to prevent or combat infection requires a better understanding of how an implanted foreign body prevents the immune system from eradicating surface-colonizing pathogens. The objective of this review is to chart factors resulting in sub-optimal clearance of Staphylococcus aureus bacteria involved in BAIs. To this end, we first describe three categories of bacterial mechanisms to counter the host immune system around foreign bodies: direct interaction with host cells, modulation of intercellular communication, and evasion of the immune system. These mechanisms take place in a time frame that differentiates sterile foreign body reactions, BAIs, and soft tissue infections. In addition, we identify experimental interventions in S. aureus BAI that may impact infectious mechanisms. Most experimental treatments modulate the host response to infection or alter the course of BAI through implant surface modulation. In conclusion, the first week after implantation and infection is crucial for the establishment of an S. aureus biofilm that resists the local immune reaction and antibiotic treatment. Although established and chronic S. aureus BAI is still treatable and manageable, the focus of interventions should lie on this first period.

Atopic dermatitis (AD) is a chronic inflammatory skin disease and colonization by Staphylococcus aureus may affect up to 100% of these patients. Virulent and resistant isolates can worsen AD patient clinical condition and jeopardize the treatment. We aimed to detect virulence genes and to evaluate the biofilm production of S. aureus isolates from infected skin lesions of children with AD. Methicillin resistance was detected by phenotypic and molecular tests and the virulence genes were detected by PCR. Biofilm formation was assessed by bacterial growing on microtiter plates and later stained with safranin. Genotyping was performed by Pulsed-Field Gel Electrophoresis and Multilocus Sequence Typing. Among 106 AD patients, 55 (51.8%) had developed S. aureus cutaneous infections and 23 (41.6%) were methicillin-resistant (MRSA). All 55 isolates carried the fnbA, hla, icaA, sasG, and seu genes, and more than 70% presented cna, eap, ebpS, hlg, and pvl genes. Clonal complex (CC) 30 was the main lineage found (34.5%), especially among MRSA isolates (52.2%). The egc cluster and the bbp gene were significantly the most frequent in MRSA isolates and in USA1100/ST30/CC30 lineage. Most of the isolates (74.5%) were non-biofilm producers and many of them only started to produce it in the presence of fibrinogen. There was no significant association between S. aureus isolates features and the AD severity. This study demonstrated a high frequency of CC30 MRSA isolates presenting several virulence genes in infected skin lesions of AD children in Brazil, that may influence the severity of the disease and the treatments required.

Staphylococcus aureus is a microbe associated with human’s food poisoning. It is caused by isolates producing different heat stable enterotoxins which act as one of the most spread worldwide gastroenteritis causes. The goal of the current study was to assess the incidence of S. aureus (enterotoxigenic) in the raw milk samples of cows which were collected from various places of Baghdad city. Isolation and identification of S. aureus were done by conventional laboratory method and the diagnoses were confirmed by using molecular method RT-PCR to detect the specific gene of S. aureus nuc gene. In addition, we investigate the occurrence of some of Staphylococcal enterotoxins genes such as SEA, SEB, SEC, SED, and SEE. We found that 12/50 (24%) of the isolates were S. aureus and these isolates carried one or more of the enterotoxin genes such as enterotoxin type SEC 12/12 (100) followed by enterotoxin type SEA 7/12 (58.33%) and only 1/12 (8.33%) was type SED, while type SEB and SEE were negative 0%. Some of the isolates have genes that coded for two enterotoxins patterns such as SEA and SEC 7/12 (58.33%) and SEC and SED 1/12 (8.33%). Fewer of the isolates expressed only one genotype of enterotoxin gene like SEC 4/12 (33.3%). This study has proven that there was a high chance of occurrence for the enterotoxigenic S. aureus at the raw milk of cows in Baghdad city.

Topicality. Up to 90% of patients with atopic dermatitis are colonized with S. aureus, with S. aureus predominance being unique to atopic dermatitis. TLR2 play a role in the presentation of S. aureus antigens in a course of atopic dermatits. Purpose - to investigate the association of rs4696480 polymorphism in TLR2 gene and S. aureus skin colonization. Materials and methods. The study included 101 patients with eczema and 84 healthy children. Skin swab cultures were taken. Subjects were classified as carriers if the cultures were positive, while those with culture found to be negative were classified as non-carriers. Genotyping for TLR2 rs4696480 was performed by using Real-time PCR. Results. We determined the prevalence of S. aureus carriage in a cohort study of atopic dermatitis patients in Ukraine. Skin culture for the presence of S. aureus was performed in 82 patients: 45.1% children had positive culture for S. aureus, 54.9% had a negative result. SCORing Atopic Dermatitis (SCORAD) index was significantly higher in S. aureus carriers (p0.05). AA genotype was significantly more frequent among S. aureus carriers (OR=2.745 (95% CI 0.865-8.708) for AT genotype, OR=7.000 (95% CI 1.852-26.462) for TT genotype. To our knowledge, the association of T16934A (rs4696480) and S. aureus colonization of lesion skin in children with atopic dermatitis have not been studied before. Conclusions. AA variant of TLR2 rs4696480 polymorphism predisposes to S. aureus colonization of skin in children with atopic dermatits. The research was carried out in accordance with the principles of the Helsinki Declaration. The study protocol was approved by the Local Ethics Committee of the participating institution. The informed consent of the patient was obtained for conducting the studies. No conflict of interests was declared by the author., Актуальность. До 90% пациентов с атопическим дерматитом колонизированы S. aureus, причем преобладание S. aureus характерно только для атопического дерматита. TLR2 играют роль в презентации антигенов S. aureus в течении атопического дерматита. Цель - изучить связь полиморфизма rs4696480 в гене TLR2 и колонизации кожи S. aureus. Материалы и методы. В исследование включен 101 больной экземой и 84 здоровых ребенка. Взято посев мазков кожи. Больные классифицированы как носители, если культуры были положительными, а те, у кого культура оказалась отрицательной, - как неносители. Генотипирование для TLR2 rs4696480 проведено с помощью полимеразной цепной реакции в реальном времени. Результаты. Определена распространенность носительства S. aureus в когортном исследовании пациентов с атопическим дерматитом в Украине. Посев кожи на наличие S. aureus проведен у 82 пациентов: 45,1% пациентов имели положительный посев на S. aureus, 54,9% - отрицательный. Балл SCORing Atopic Dermatitis (SCORAD) был достоверно выше у носителей S. aureus (p0,05). AA-генотип более часто встречался среди носителей S. aureus (ОШ=2,745 (95% ДИ: 0,865-8,708) для AT-генотипа, ОШ=7,000 (95% ДИ: 1,852-26,462) для TT-генотипа). Насколько известно, ассоциация T16934A (rs4696480) и колонизации S. aureus пораженной кожи у детей с атопическим дерматитом ранее не исследовалась. Выводы. AA-вариант полиморфизма TLR2 rs4696480 предрасполагает к колонизации кожи S. aureus у детей с атопическим дерматитом. Исследование выполнено в соответствии с принципами Хельсинкской декларации. Протокол исследования одобрен Локальным этическим комитетом участвующего учреждения. На проведение исследований получено информированное согласие родителей детей. Автор заявляет об отсутствии конфликта интересов., Актуальність. До 90% пацієнтів з атопічним дерматитом колонізовані S. aureus, причому переважання S. aureus є характерним лише для атопічного дерматиту. TLR2 відіграють роль у презентації антигенів S. aureus у перебігу атопічного дерматиту. Мета - вивчити зв’язок поліморфізму rs4696480 у гені TLR2 та колонізації шкіри S. aureus. Матеріали та методи. До дослідження залучено 101 хворого на екзему та 84 здорові дитини. Взято посів мазків шкіри. Хворих класифіковано як носіїв, якщо культури були позитивними, а тих, у кого культура виявилася негативною, - як неносіїв. Генотипування для TLR2 rs4696480 проведено за допомогою полімеразної ланцюгової реакції в реальному часі. Результати. Визначено поширеність носійства S. aureus у когортному дослідженні пацієнтів з атопічним дерматитом в Україні. Посів шкіри на наявність S. aureus проведено у 82 пацієнтів: 45,1% пацієнтів мали позитивний посів на S. aureus, 54,9% - негативний. Бал SCORing Atopic Dermatitis (SCORAD) був достовірно вищим у носіїв S. aureus (p0,05). AA-генотип достовірно частіше зустрічався серед носіїв S.aureus (ВШ=2,745 (95% ДІ: 0,865-8,708) для AT-генотипу, ВШ=7,000 (95% ДI: 1,852-26,462) для TT-генотипу). Наскільки нам відомо, асоціація T16934A (rs4696480) та S. aureus колонізації ураженої шкіри у дітей з атопічним дерматитом раніше не досліджувалася. Висновки. AA-варіант поліморфізму TLR2 rs4696480 схиляє до колонізації шкіри S. aureus у дітей з атопічним дерматитом. Дослідження виконано відповідно до принципів Гельсінської декларації. Протокол дослідження ухвалено Локальним етичним комітетом зазначеної в роботі установи. На проведення досліджень отримано інформовану згоду батьків дітей. Автор заявляє про відсутність конфлікту інтересів.

Background: The opportunistic pathogen Staphylococcus aureus is an asymptomatically carried member of the microbiome of about one third of the human population at any given point in time. Body sites known to harbor S. aureus are the skin, nasopharynx, and gut. In particular, the mechanisms allowing S. aureus to pass the gut epithelial barrier and to invade the bloodstream were so far poorly understood. Therefore, the objective of our present study was to investigate the extent to which genetic differences between enteric S. aureus isolates and isolates that caused serious bloodstream infections contribute to the likelihood of invasive disease. Results: Here, we present genome-wide association studies (GWAS) that compare the genome sequences of 69 S. aureus isolates from enteric carriage by healthy volunteers and 95 isolates from bloodstream infections. We complement our GWAS results with a detailed characterization of the cellular and extracellular proteomes of the representative gut and bloodstream isolates, and by assaying the virulence of these isolates with infection models based on human gut epithelial cells, human blood cells, and a small animal infection model. Intriguingly, our results show that enteric and bloodstream isolates with the same sequence type (ST1 or ST5) are very similar to each other at the genomic and proteomic levels. Nonetheless, bloodstream isolates are not necessarily associated with an invasive profile. Furthermore, we show that the main decisive factor preventing infection of gut epithelial cells in vitro is the presence of a tight barrier. Conclusions: Our data show that virulence is a highly variable trait, even within a single clone. Importantly, however, there is no evidence that blood stream isolates possess a higher virulence potential than those from the enteric carriage. In fact, some gut isolates from healthy carriers were more virulent than bloodstream isolates. Based on our present observations, we propose that the integrity of the gut epithelial layer, rather than the pathogenic potential of the investigated enteric S. aureus isolates, determines whether staphylococci from the gut microbiome will become invasive pathogens. E.J.M.R. received funding from the CEC MSCI-ITN grant 713482 (ALERT). M.W. was supported by the China Scholarship Council (grant 201708110184). Part of this work was performed at the UMCG Imaging and Microscopy Center (UMIC), which is sponsored by grants from The Netherlands Organization for Scientific Research (175.010.2009–023, Zeiss LSM7/780 confocal and ZonMW 91111.006, Zeiss Supra55 ATLAS). This work was partially supported by the INTERREG VA (202085) funded project EurHealth-1Health, part of a Dutch-German cross-border network supported by the European Commission, the Dutch Ministry of Health, Welfare and Sports (VWS), the Ministry of Economy, Innovation, Digitalisation and Energy of the German Federal State of North Rhine-Westphalia and the German Federal State of Lower Saxony. Sí

The aim of this study was to investigate the presence of exfoliative toxin genes (eta, etb, etd) in S. aureus strains isolated from nursing students, university students and hospital surfaces. A total of 50 S. aureus strains isolated from 20 nursing students, 17 university students and 13 hospital surfaces were used in this study. The presence of exfoliative toxin (ET) genes (eta, etb and etd) was investigated by PCR. PFGE was used to investigate the clonal relationship of ET gene detected isolates. While etd gene was detected in 6% (3/50) in our study, eta and etb genes could not be detected. Two of the isolates with the etd gene were nursing students and one was a university student isolate. No ET gene was detected in any of the hospital surface isolates. It was determined that the isolates with etd gene detected were clonal related. Since S. aureus strains carrying exfoliative genes cause both community and healthcare-associated infections, comprehensive studies are needed to prevent infections that may arise from such strains.

Peer reviewed: True, Staphylococcus aureus is an important pathogen associated with hospital, community, and livestock-acquired infections, with the ability to develop resistance to antibiotics. Nasal carriage by hospital inpatients is a risk for opportunistic infections. Antibiotic susceptibility patterns, virulence genes and genetic population structure of S. aureus nasal isolates, from inpatients at Busia County Referral Hospital (BCRH) were analyzed. A total of 263 inpatients were randomly sampled, from May to July 2015. The majority of inpatients (85.9%) were treated empirically with antimicrobials, including ceftriaxone (65.8%) and metronidazole (49.8%). Thirty S. aureus isolates were cultured from 29 inpatients with a prevalence of 11% (10.3% methicillin-susceptible S. aureus (MSSA), 0.8% methicillin resistant S. aureus (MRSA)). Phenotypic and genotypic resistance was highest to penicillin-G (96.8%), trimethoprim (73.3%), and tetracycline (13.3%) with 20% of isolates classified as multidrug resistant. Virulence genes, Panton-Valentine leukocidin (pvl), toxic shock syndrome toxin-1 (tsst-1), and sasX gene were detected in 16.7%, 23.3% and 3.3% of isolates. Phylogenetic analysis showed 4 predominant clonal complexes CC152, CC8, CC80, and CC508. This study has identified that inpatients of BCRH were carriers of S. aureus harbouring virulence genes and resistance to a range of antibiotics. This may indicate a public health risk to other patients and the community.