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Vaccination arguably remains the only long-term strategy to limit the spread of S. aureus infections and its related antibiotic resistance. To date, however, all staphylococcal vaccines tested in clinical trials have failed. In this review, we propose that the failure of S. aureus vaccines is intricately linked to prior host exposure to S. aureus and the pathogens capacity to evade adaptive immune defenses. We suggest that non-protective immune imprints created by previous exposure to S. aureus are preferentially recalled by SA vaccines, and IL-10 induced by S. aureus plays a unique role in shaping these non-protective anti-staphylococcal immune responses. We discuss how S. aureus modifies the host immune landscape, which thereby necessitates alternative approaches to develop successful staphylococcal vaccines.

The failure of the Staphylococcus aureus (SA) IsdB vaccine trial can be explained by the recall of non-protective immune imprints from prior SA exposure. Here, we investigate natural human SA humoral imprints to understand their broader impact on SA immunizations. We show that antibody responses against SA cell-wall-associated antigens (CWAs) are non-opsonic, while antibodies against SA toxins are neutralizing. Importantly, the protective characteristics of the antibody imprints accurately predict the failure of corresponding vaccines against CWAs and support vaccination against toxins. In passive immunization platforms, natural anti-SA human antibodies reduce the efficacy of the human monoclonal antibodies suvratoxumab and tefibazumab, consistent with the results of their respective clinical trials. Strikingly, in the absence of specific humoral memory responses, active immunizations are efficacious in both naive and SA-experienced mice. Overall, our study points to a practical and predictive approach to evaluate and develop SA vaccines based on pre-existing humoral imprint characteristics.

Objective: The purpose of this study is a new update on the resistance profile, Macrolide–Lincosamide–Streptogramin B resistance mechanisms and biofilm formation in the Staphylococcus aureus isolated from health care workers (HCWs) nasal carriage at a children's teaching hospital in Babol (Northern Iran). Results: A total of 143 non-repetitive nasal swab samples were collected from volunteers, where 53.8% (n; 77/143) were HCWs, 33.6% (n; 48/143) medical students, and 12.6% (n; 18/143) resident students. The prevalence of nasal carriers of S. aureus was 22.4% (n; 32/143), among them, 40.6% (n; 13/32) were identified as methicillin-resistant Staphylococcus aureus (MRSA(carriers. Antimicrobial susceptibility testing showed that erythromycin (68.8%, n; 22/32) and ciprofloxacin (15.6%, n; 5/32) had the highest and lowest resistance rate, respectively. The frequency of resistance genes in the strains was as follows; ermC (n; 17/32, 53.1%), ermA (n; 11/32, 34.4%), ermB (n; 6/32, 18.7%), ereA (n; 3/32, 9.4%). Moreover, 50.0% (n; 16/32), 28.1% (n; 9/32) and 21.8% (n; 7/32) of isolates were strongly, weakly and moderately biofilm producer, respectively. Macrolides-lincosamides-streptogramins B (MLSB) antibiotic resistance among S. aureus isolates from HCWs nasal carriage have found significant prevalence rates throughout the globe. It is crucial to remember that the development of biofilms and MLS B antibiotic resistance are both dynamic processes. [ABSTRACT FROM AUTHOR]

Eugenol, as a natural antibacterial agent, has been widely studied for its inhibitory effect on the common food-borne pathogen Staphylococcus aureus (S. aureus). However, the widespread application of eugenol is still limited by its instability and volatility. Herein, γ-polyglutamic acid coated eugenol cationic liposomes (pGA-ECLPs) were successfully constructed by self-assembly with an average particle size of 170.7 nm and an encapsulation efficiency of 36.2%. The formation of pGA shell significantly improved the stability of liposomes, and the encapsulation efficiency of eugenol only decreased by 20.7% after 30 days of storage at 4 °C. On the other hand, the pGA layer can be hydrolyzed by S. aureus, achieving effective control of release through response to bacterial stimuli. The application experiments further confirmed that pGA-ECLPs effectively prolonged the antibacterial effect of eugenol in fresh chicken without causing obvious sensory effects on the food. The above results of this study provide an important reference for extending the action time of natural antibacterial substances and developing new stimuli-responsive antibacterial systems. [ABSTRACT FROM AUTHOR]

Background: The rapid rise of microbial resistance to traditional antibiotics has caused grave concerns for the treatment of infectious diseases. This serious problem increases the demand for significant plant-based antibacterial and antimicrobial drugs. Kalanchoe pinnata is one of the plants that has had significant antibacterial effects due to the presence of a wide range of bioactive compounds, so it could be an effective substitute for the current synthetic antibiotics. The study aimed to evaluate the anti-bacterial and antioxidant properties of a methanolic extract of Kalanchoe pinnata leaves. Materials and Methods: The preliminary phytochemical screening was performed using standard biochemical assays. The anti-bacterial activity was determined against multidrugresistant E. coli and S. aureus using the well-diffusion method. The 2,2-diphenyl-1-picrylhydrazyl and ferric ion reducing antioxidant potential assays were used to evaluate the antioxidant activity. Results: The methanolic extract of Kalanchoe pinnata leaves showed the presence of flavonoids, saponins, steroids, phenol, quinones, and proteins. The remarkable anti-bacterial activities were displayed against multidrug-resistant E. coli and S. aureus, with minimum inhibitory concentration values of 50 mg/mL and 12.5 mg/mL, respectively. The significant antioxidant activity was exhibited in 2,2-diphenyl-1-picrylhydrazyl and ferric ion reducing antioxidant potential assays. Conclusion: The results of this investigation suggested that the Kalanchoe pinnata extract may be useful as an alternative for antibiotics and may have pharmacological promise in the treatment of many diseases. [ABSTRACT FROM AUTHOR]

Dayak tribes indigenous to the Indonesian island of Borneo has been using Bajakah Kalalawit (Uncaria gambir Roxb.) as traditional medicine for ages. This inspired us to develop phenolic from Bajakah Kalalawit extract as antibacterial agent. The extraction was done through decoction method and the determination of phenolic concentration was done using a visible spectrophotometer and Folin–Ciocalteu reagent (mixture of phosphotungstic and phosphomolybdic acids). We investigated the possibility of developing phenolic nanoparticle for future work. Kirby-Bauer method was used to assess antibacterial activity of phenolic against Staphylococcus aureus and the results were compared to Chloramphenicol in terms of its efficacy and duration of inhibition. This study contributes to the ongoing effort to address antibiotic resistance through the development of innovative antibacterial agents derived from natural sources. The results provide valuable insights into the potential of Bajakah Kalalawit phenolic extracts as a promising avenue for combating bacterial infections in the future. [ABSTRACT FROM AUTHOR]

Resistant biofilms formed by Staphylococcus aureus on medical devices pose a constant medical threat. A promising alternative to tackle this problem is photodynamic inactivation (PDI). This study focuses on a polyurethane (PU) material with an antimicrobial surface consisting of a composite based on silicate, polycation, and erythrosine B (EryB). The composite was characterized using X-ray diffraction and spectroscopy methods. Anti-biofilm effectiveness was determined after PDI by calculation of CFU mL−1. The liquid PU precursors penetrated a thin silicate film resulting in effective binding of the PU/silicate composite and the PU bulk phases. The incorporation of EryB into the composite matrix did not significantly alter the spectral properties or photoactivity of the dye. A green LED lamp and laser were used for PDI, while irradiation was performed for different periods. Preliminary experiments with EryB solutions on planktonic cells and biofilms optimized the conditions for PDI on the nanocomposite materials. Significant eradication of S. aureus biofilm on the composite surface was achieved by irradiation with an LED lamp and laser for 1.5 h and 10 min, respectively, resulting in a 10,000-fold reduction in biofilm growth. These results demonstrate potential for the development of antimicrobial polymer surfaces for modification of medical materials and devices. [ABSTRACT FROM AUTHOR]

Biofilm-protected pathogenic Staphylococcus aureus causes chronic infections that are difficult to treat. An essential building block of these biofilms are functional amyloid fibrils that assemble from phenol-soluble modulins (PSMs). PSMα1 cross-seeds other PSMs into cross-β amyloid folds and is therefore a key element in initiating biofilm formation. However, the paucity of high-resolution structures hinders efforts to prevent amyloid assembly and biofilm formation. Here, we present a 3.5 Å resolution density map of the major PSMα1 fibril form revealing a left-handed cross-β fibril composed of two C2-symmetric U-shaped protofilaments whose subunits are unusually tilted out-of-plane. Monomeric α-helical PSMα1 is extremely cytotoxic to cells, despite the moderate toxicity of the cross-β fibril. We suggest mechanistic insights into the PSM functional amyloid formation and conformation transformation on the path from monomer-to-fibril formation. Details of PSMα1 assembly and fibril polymorphism suggest how S. aureus utilizes functional amyloids to form biofilms and establish a framework for developing therapeutics against infection and antimicrobial resistance. [ABSTRACT FROM AUTHOR]

Background: Multi-drug resistant Staphylococcus aureus is one of the most common causes of nosocomial and community-acquired infections, with high morbidity and mortality. Treatment of such infections is particularly problematic; hence, it is complicated by antibiotic resistance, and there is currently no reliable vaccine. Furthermore, it is well known that S. aureus produces an exceptionally large number of virulence factors that worsen infection. Consequently, the urgent need for anti-virulent agents that inhibit biofilm formation and virulence factors has gained momentum. Therefore, we focused our attention on an already-approved antibiotic and explored whether changing the dosage would still result in the intended anti-virulence effect. Methods: In the present study, we determined the antibiotic resistance patterns and the MICs of oxacillin against 70 MDR S. aureus isolates. We also investigated the effect of sub-MICs of oxacillin (at 1/4 and 1/8 MICs) on biofilm formation using the crystal violet assay, the phenol-sulphuric acid method, and confocal laser scanning microscopy (CLSM). We examined the effect of sub-MICs on virulence factors and bacterial morphology using quantitative reverse transcription polymerase chain reaction (qRT-PCR) and electron microscopy, respectively. Moreover, we studied the effect of sub-MICs of oxacillin (OX) in-vivo using a wound infection model. Results: Oxacillin at 1/2 MIC showed a significant decrease in bacterial viability, while 1/4 and 1/8 MICs had negligible effects on treated bacterial isolates. Treatment of MDR isolates with 1/4 or 1/8 MICs of oxacillin significantly reduced biofilm formation (64% and 40%, respectively). The treated MDR S. aureus with sub-MICs of OX exhibited a dramatic reduction in several virulence factors, including protease, hemolysin, coagulase, and toxic shock syndrome toxin-1 (TSST-1) production. The sub-MICs of OX significantly decreased (P < 0.05) the gene expression of biofilm and virulence-associated genes such as agrA, icaA, coa, and tst. Furthermore, oxacillin at sub-MICs dramatically accelerated wound healing, according to the recorded scoring of histological parameters. Conclusion: The treatment of MDR S. aureus with sub-MICs of oxacillin can help in combating the bacterial resistance and may be considered a promising approach to attenuating the severity of S. aureus infections due to the unique anti-biofilm and anti-virulence activities. [ABSTRACT FROM AUTHOR]

Aims Staphylococcus aureus is an opportunistic pathogen whose treatment is further complicated by its ability to form biofilms. In this study, we examine the impact of growing S. aureus biofilms on different polymerizing surfaces, specifically agar and agarose, on the pathogen's tolerance to fluoroquinolones. Methods and results Biofilms of two methicillin-resistant strains of S. aureus were grown on agar or agarose in the presence of the same added nutrients, and their antibiotic susceptibility to two fluoroquinolones, moxifloxacin (MXF) and delafloxacin (DLX), were measured. We also compared the metabolism and extracellular polymeric substances (EPS) production of biofilms that were grown on agar and agarose. Conclusions Biofilms that were grown on agarose were consistently more susceptible to antibiotics than those grown on agar. We found that in biofilms that were grown on agar, extracellular protein composition was higher, and adding EPS to agarose-grown biofilms increased their tolerance to DLX to levels that were comparable to agar-grown biofilms. [ABSTRACT FROM AUTHOR]

Purpose: There is currently no ideal radiotracer for imaging bacterial infections. Radiolabelled d-amino acids are promising candidates because they are actively incorporated into the peptidoglycan of the bacterial cell wall, a structural feature which is absent in human cells. This work describes fluorine-18 labelled analogues of d-tyrosine and d-methionine, O-(2-[18F]fluoroethyl)-d-tyrosine (d-[18F]FET) and S-(3-[18F]fluoropropyl)-d-homocysteine (d-[18F]FPHCys), and their pilot evaluation studies as potential radiotracers for imaging bacterial infection. Procedures: d-[18F]FET and d-[18F]FPHCys were prepared in classical fluorination-deprotection reactions, and their uptake in Staphylococcus aureus and Pseudomonas aeruginosa was evaluated over 2 h. Heat killed bacteria were used as controls. A clinically-relevant foreign body model of S. aureus infection was established in Balb/c mice, as well as a sterile foreign body to mimic inflammation. The ex vivo biodistribution of d-[18F]FPHCys in the infected and inflamed mice was evaluated after 1 h, by dissection and gamma counting. The uptake was compared to that of [18F]FDG. Results: In vitro uptake of both d-[18F]FET and d-[18F]FPHCys was specific to live bacteria. Uptake was higher in S. aureus than in P. aeruginosa for both radiotracers, and of the two, higher for d-[18F]FPHCys than d-[18F]FET. Blocking experiments with non-radioactive d-[19F]FPHCys confirmed specificity of uptake. In vivo, d-[18F]FPHCys had greater accumulation in S. aureus infection compared with sterile inflammation, which was statistically significant. As anticipated, [18F]FDG showed no significant difference in uptake between infection and inflammation. Conclusions: d-[18F]FPHCys uptake was higher in infected tissues than inflammation, and represents a fluorine-18 labelled d-AA with potential to detect a S. aureus reference strain (Xen29) in vivo. Additional studies are needed to evaluate uptake of this radiotracer in clinical isolates. [ABSTRACT FROM AUTHOR]

In the complex realm of bacterial infections, particularly those caused by Staphylococcus aureus (S. aureus), macrophages play a pivotal role in orchestrating the immune response. During the initial stages of infection, the monocytes give rise to macrophages with a pro-inflammatory (M1 type) behaviour, engulfing and neutralizing the invading pathogens. However, under the sustained influence of S. aureus infection, monocytes can undergo a transition into an anti-inflammatory M2 state (pro-infection) rather than the M1 state (anti-infection), thereby compromising effective infection control. Therefore, it is necessary to develop a strategy that would preserve the pro-inflammatory functions of macrophages, in a safe and controlled manner. For this, we focused on harnessing the potential of S. aureus-derived ghost cells (GCs) which are non-live empty envelopes of bacterial cells, but with the antigenic determinants intact. Through a unique Lugol’s-iodine treatment, we generated GCs and characterization of these GCs using gel electrophoresis, FTIR, flow cytometry, TEM, and SEM confirmed their structural integrity. Following this, we assessed the extend of cellular association of the GCs with RAW267.4 macrophages, and observed an immediate interaction between the two, as evident from the flowcytometry and microscopy studies. We then performed macrophage polarisation on a human monocyte-macrophage model cell line, THP-1. Our findings revealed that GCs effectively activated macrophages, and promoted a pro-inflammatory polarisation with the expression of M1 differentiation markers (CD86, TNFα, IL-1β, IL-6, IL-12) evaluated through both qPCR and ELISA. Interestingly an intermediary expression of M2 markers viz., CD206 and IL-10 was also observed, but was overruled by the enhanced expression of M1 markers at a later time point. Overall, our study introduces a novel approach utilizing GCs to guide naïve macrophages towards M1 subtypes, thereby potentiating immune responses during microbial infections. This innovative strategy can modulate macrophage function, ultimately improving outcomes in S. aureus infections and beyond.Highlights: A simplistic protocol developed for obtaining ghost cells (GC) from S. aureus. High cellular interaction of GCs demonstrated in macrophages within short incubation time intervals. GCs induced M1 macrophage polarization, upregulating markers like CD86 and cytokines TNF-α, IL-1β, IL-6, and IL-12. Selective M1 polarization demonstrated by GCs evident from the downregulation the anti-inflammatory cytokine IL-10. Novel approach for immunotherapy in S. aureus infections via pro-inflammatory (M1) polarization of macrophages. [ABSTRACT FROM AUTHOR]

Children carrying Staphylococcus aureus in their nasopharynx are at a higher risk of contracting systemic infection. Due to lack of sufficient information regarding such carriage, this study was conducted to explore the prevalence, antibiotic susceptibility, and genomic profiles of S. aureus isolated from nasopharyngeal samples of 163 randomly selected asymptomatic Bangladeshi children aged from 5–<15 years. Antibiotic susceptibility pattern and genomic analysis of the samples were conducted using standard microbiological methods and genomic tools. The carriage was confirmed in 44 (27%) children who were mostly well nourished without respiratory symptoms in the last 3 months. Higher carriage was observed among the younger age group (5–<10 years) who completed vaccines for pneumonia (p = 0.002) and influenza (p = 0.004). Among the isolates, 84.1% were multidrug-resistant and 47.5% (n = 40) were methicillin-resistant S. aureus (MRSA). All the isolates (100%) were resistant to cefixime with higher resistance to ampicillin (95.5%) and penicillin (90.9%). Among the three investigated isolates, two were ST80 (ID-1 and ID-52) and one was a novel strain (ID-19) with the presence of aph-Stph, blaI, blaZ, dha1, fosB, lmrS, mepA, norA, and tet38 genes. The current research demonstrates a high incidence of multidrug-resistant S. aureus and reports the first instance of ST80 in asymptomatic children in Bangladesh. [ABSTRACT FROM AUTHOR]

One of the greatest challenges worldwide is containing the spread of problematic microorganisms. A promising approach is the use of antimicrobial coatings (AMCs). The antimicrobial potential of certain metals, including copper and zinc, has already been verified. In this study, polyethylene terephthalate and aluminum (PET-Al) foils were coated with copper, zinc, and a combination of these two metals, known as core–shell particles, respectively. The resistance of the three different types of coatings to mechanical and chemical exposure was evaluated in various ways. Further, the bacteria Staphylococcus aureus and the bacteriophage ϕ6 were used to assess the antimicrobial efficacy of the coatings. The best efficacy was achieved with the pure copper coating, which was not convincing in the abrasion tests. The result was a considerable loss of copper particles on the surfaces and reduced effectiveness against the microorganisms. The core–shell particles demonstrated better adhesion to the surfaces after abrasion tests and against most chemical agents. In addition, the antimicrobial efficiency remained more stable after the washability treatment. Thus, the core–shell particles had several benefits over the pure copper and zinc coatings. In addition, the best core–shell loading for durability and efficacy was determined in this study. [ABSTRACT FROM AUTHOR]

Biofilms on dry hospital surfaces can enhance the persistence of micro-organisms on dry harsh clinical surfaces and can potentially act as reservoirs of infectious agents on contaminated surfaces. This study was conducted to quantify the transfer of viable Staphylococcus aureus cells from dry biofilms through touching and to investigate the impact of nutrient and moisture deprivation on virulence levels in S. aureus. Dry biofilms of S. aureus ATCC 25923 and a defective biofilm-forming ability mutant, S. aureus 1132, were formed in 24-well plates under optimized conditions mimicking dry biofilm formation on clinical surfaces. Microbial cell transfer was induced through the touching of the dry biofilms, which were quantified on nutrient agar. To investigate the impact of nutrient and moisture deprivation on virulence levels, dry and standard biofilms as well as planktonic cells of S. aureus ATCC 25923 were inoculated into Galleria mellonella and their kill rates compared. Results of this study showed that viable cells from dry biofilms of S. aureus ATCC 25923 were significantly more virulent and readily transferrable from dry biofilms through a touch test, therefore representing a greater risk of infection. The biofilm-forming capability of S. aureus strains had no significant impact on their transferability with more cells transferring when biofilm surfaces were wet. These findings indicate that dry biofilms on hospital surfaces may serve as a reservoir for the dissemination of pathogenic micro-organisms in hospitals, thus highlighting the importance of regular cleaning and adequate disinfection of hospital surfaces. [ABSTRACT FROM AUTHOR]

Background: Staphylococcus aureus (S. aureus) is a leading cause of skin and soft tissue infections, with antibiotic-resistant strains causing potentially life-threatening diseases. This study explored the antimicrobial potential of Acacia ehrenbergiana (Hayne) and Prosopis juliflora using a Caenorhabditis elegans (C. elegans) in vivo model infected with methicillin-susceptible (MSSA) and methicillin-resistant (MRSA) S. aureus strains. Methods: Wild-type C. elegans were exposed to MSSA strain ATCC 25923 and MRSA strains ATCC BF195 and ATCC BC 3820 using an agar-based killing assay. The impact of ethanol extracts from A. ehrenbergiana and P. juliflora on the survival of infected C. elegans was assessed by analyzing the survival rates of infected and non-infected worms. The effects of the plant extracts on C. elegans feeding rate and colonization of MSSA and MRSA in the worm's gut were also examined. Additionally, in vitro assays were conducted to assess the bactericidal and/or bacteriostatic effects of the plant extracts. Results: Exposure to MSSA and MRSA strains significantly reduced C. elegans lifespan, with a mean time to death (TDmean) of 72 ± 1.3 h. Treatment with 100–500 μg/ml of either plant extract increased C. elegans survival by 65–70%. The extracts did not affect C. elegans pharyngeal pumping. Colony-forming Unit (CFU) assays showed a significant reduction in MSSA and MRSA colonization in the worm intestine with P. juliflora, but not A. ehrenbergiana extracts. In vitro Minimum Inhibitory Concentration (MIC) assays indicated that neither extract had direct bactericidal activity, suggesting the observed reduction in bacterial infection in worms was likely due to enhanced host immune response rather than direct antibacterial effects. Conclusion: These findings suggest that A. ehrenbergiana and P. juliflora extracts enhance C. elegans survival upon infection through indirect mechanisms, possibly involving immune system activation. This study highlights the potential of these extracts as antibacterial agents against MSSA and MRSA strains. [ABSTRACT FROM AUTHOR]

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This study evaluated cryogels from albumin (ALB) and albumin–pectin (ALB:PEC) as carriers for pink pepper (Schinus terebinthifolius Raddi) essential oil. Cryogels were evaluated through infrared spectrophotometry, X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry. The bioactivity of the cryogels was analyzed by measuring their encapsulation efficiency (EE%), the antimicrobial activity of the encapsulated oil against S. aureus, E. coli, and B. cereus using the agar diffusion method; total phenolic content and antioxidant activity were analyzed by UV-vis spectrophotometry. The EE% varied between 59.61% and 77.41%. The cryogel with only ALB had the highest total phenolic content with 2.802 mg GAE/g, while the cryogel with the 30:70 ratio (ALB:PEC) presented a value of 0.822 mg GAE/g. A higher proportion of PEC resulted in a more significant inhibitory activity against S. aureus, reaching an inhibition zone of 18.67 mm. The cryogels with ALB and 70:30 ratio (ALB:PEC) presented fusion endotherms at 137.16 °C and 134.15 °C, respectively, and semicrystalline structures. The interaction between ALB and PEC increased with their concentration, as evidenced by the decreased intensity of the O-H stretching peak, leading to lower encapsulation efficiency. The cryogels obtained can be considered a suitable matrix for encapsulating pink pepper oil. [ABSTRACT FROM AUTHOR]

Staphylococcus aureus [S. aureus] is a leading cause of sepsis and septic arthritis, conditions that pose significant medical challenges due to their high mortality and morbidity. No studies have used an in vivo imaging system [IVIS] to monitor S. aureus sepsis and septic arthritis. Here, we employed a bioluminescent reporter strain of S. aureus, Newman AH5016, administered intravenously to induce sepsis and intra-articularly to induce local septic arthritis in mice. Disease progression was monitored using IVIS to capture bioluminescent signals from kidneys, joints, and whole mice. Cytokines in the blood and joints were measured. The efficacy of cloxacillin treatment was evaluated. In the sepsis model, bioluminescent signals from kidneys, but not from whole mice, were correlated with kidney bacterial load and abscess formation. Ex vivo kidney imaging detected increased bacterial load and abscess formation from day 3 to day 10. Antibiotic treatment significantly reduced kidney signals, correlating with decreased bacterial counts and IL-6 levels, indicating effective infection control. In the local infection model, early-phase bioluminescent signals from joints were correlated with macroscopic arthritis and bacterial burden. Thus, signal detection from kidneys using IVIS is useful for monitoring S. aureus sepsis and assessing antibiotic efficacy, though it may only be effective for early-phase monitoring of local septic arthritis. [ABSTRACT FROM AUTHOR]

Bacteria in natural ecosystems such as soil, dirt, or debris preferentially reside in the biofilm phenotype. When a traumatic injury, such as an open fracture, occurs, these naturally dwelling biofilms and accompanying foreign material can contaminate the injury site. Given their high tolerance of systemic levels of antibiotics that may be administered prophylactically, biofilms may contribute to difficult-to-treat infections. In most animal models, planktonic bacteria are used as initial inocula to cause infection, and this might not accurately mimic clinically relevant contamination and infection scenarios. Further, few approaches and systems utilize the same biofilm and accompanying substrate throughout the experimental continuum. In this study, we designed a unique reactor to grow bacterial biofilms on up to 50 silica beads that modeled environmental wound contaminants. The data obtained indicated that the reactor system repeatably produced mature Staphylococcus aureus and Pseudomonas aeruginosa biofilms on the silica beads, with an average of 5.53 and 6.21 log10 colony-forming units per mm2, respectively. The bead substrates are easily manipulable for in vitro or in vivo applications, thus improving translatability. Taken together, the bead biofilm reactor presented herein may be a useful system for repeatably growing established biofilms on silica beads that could be used for susceptibility testing and as initial inocula in future animal models of trauma-related injuries. [ABSTRACT FROM AUTHOR]

Staphylococcus aureus with current universal importance represents a main carrier of emerging antimicrobial resistance determinatives of global health concerns that have developed drug resistance mechanisms to the various available antibiotics. On the other hand, due to the antimicrobial potential of Nigella Sativa oil (NSO), it was hypothesized that incorporation of nano-carriers (NS-SLN and NS-chitosan (CH) nanoparticles) can enhance its antibacterial effects. This study evaluated the physico-chemical and antibacterial characteristics of NS-SLN and NS-CH. TEM images revealed a round shape with clear edges for both nanoparticles, and the average sizes were reported to be 196.4 and 446.6 nm for NS-SLN and NS-CH, respectively. The zeta potential and encapsulation efficiency were −28.9 and 59.4 mV and 73.22% and 88% for NS-SLN and NS-CH, respectively. The Minimum Inhibitory Concentrations for NSO, NS-SLN, and NS-CH against S. aureus were 480, 200, and 80 µg/mL, respectively. The results confirm significantly stronger antibacterial influences of NSO when loaded into chitosan nanoparticles as a potential candidate for nano-delivery of antimicrobial agents. [ABSTRACT FROM AUTHOR]

Background: Craniotomy is a common neurosurgery used to treat intracranial pathologies. Nearly 5% of the 14 million craniotomies performed worldwide each year become infected, most often with Staphylococcus aureus (S. aureus), which forms a biofilm on the surface of the resected bone segment to establish a chronic infection that is recalcitrant to antibiotics and immune-mediated clearance. Tumor necrosis factor (TNF), a prototypical proinflammatory cytokine, has been implicated in generating protective immunity to various infections. Although TNF is elevated during S. aureus craniotomy infection, its functional importance in regulating disease pathogenesis has not been explored. Methods: A mouse model of S. aureus craniotomy infection was used to investigate the functional importance of TNF signaling using TNF, TNFR1, and TNFR2 knockout (KO) mice by quantifying bacterial burden, immune infiltrates, inflammatory mediators, and transcriptional changes by RNA-seq. Complementary experiments examined neutrophil extracellular trap formation, leukocyte apoptosis, phagocytosis, and bactericidal activity. Results: TNF transiently regulated neutrophil and granulocytic myeloid-derived suppressor cell recruitment to the brain, subcutaneous galea, and bone flap as evident by significant reductions in both cell types between days 7 to 14 post-infection coinciding with significant decreases in several chemokines, which recovered to wild type levels by day 28. Despite these defects, bacterial burdens were similar in TNF KO and WT mice. RNA-seq revealed enhanced lymphotoxin-α (Lta) expression in TNF KO granulocytes. Since both TNF and LTα signal through TNFR1 and TNFR2, KO mice for each receptor were examined to assess potential redundancy; however, neither strain had any impact on S. aureus burden. In vitro studies revealed that TNF loss selectively altered macrophage responses to S. aureus since TNF KO macrophages displayed significant reductions in phagocytosis, apoptosis, IL-6 production, and bactericidal activity in response to live S. aureus, whereas granulocytes were not affected. Conclusion: These findings implicate TNF in modulating granulocyte recruitment during acute craniotomy infection via secondary effects on chemokine production and identify macrophages as a key cellular target of TNF action. However, the lack of changes in bacterial burden in TNF KO animals suggests the involvement of additional signals that dictate S. aureus pathogenesis during craniotomy infection. [ABSTRACT FROM AUTHOR]

Background: No consensus in the literature has been found about the necessity of implementing a decolonization screening protocol for Staphylococcus aureus in patients who undergo prosthesis implantation of the knee (TKA) or of the hip (THA), with the aim of reducing periprosthetic infections (PJIs). Methods: A systematic literature search was conducted using PubMed, Web of Science, and Embase in April 2024. Studies conducted on patients who underwent a TKA or THA and who followed a screening and decolonization protocol from S. aureus were included. The benefits of implementing this protocol were evaluated through the number of infections overall caused by S. aureus and other pathogens. The risk of bias and quality of evidence were assessed using Cochrane guidelines. Results: A total of 922 articles were evaluated, and of these, 12 were included in the study for a total of 56,930 patients. The results of the meta-analysis showed a reduced risk of overall PJI (p = 0.002), PJI caused by S. aureus (p < 0.0001), and PJI caused by MRSA (p < 0.0001) and highlighted no differences between the two groups in the onset of a PJI caused by other bacteria (p = 0.50). Conclusions: This study showed that the screening and decolonization of S. aureus in patients undergoing THA or THA procedures reduced the risk of a PJI. The screening and decolonization protocol for this kind of patient represents an important procedure for the safety of the patient and in social-economic and medico-legal terms. [ABSTRACT FROM AUTHOR]

Background: Although milk is nutritionally valuable, it also serves as a significant medium for the transmission of pathogens and their toxins. Aim: This study aimed to investigate the role of enterotoxin gene A (SEA) in the development of bovine mastitis. We accomplished this by examining milk through polymerase chain reaction (PCR) testing, amino acid substitution analysis, and phylogenetic analysis. Methods: A total of fifty milk samples were collected from locally bred dairy cows in Al-Diwaniyah, located in southern Iraq. We employed the VITEK-2 platform to validate the diagnosis of Staphylococcus aureus and confirm the results of routine tests (culturing and biochemical tests). Subsequently, the genetic mutation and phylogeny analysis were achieved utilizing DNA sequencing to 16S rRNA and enterotoxin A genes. Results: 66% (33/50) of the milk samples found to be contain S. aureus by the VITEK-2 system. Furthermore, 25/33 of the samples were positive by the PCR test. While 60% (15 out of 25) tested positive for the SEA gene. After genomic analysis, we identified amino acid substitutions of serine, glutamine with arginine, tyrosine with cysteine, and aspartic acid with glycine at positions 9, 101, 119, 187, and 191. The phylogenetic investigation demonstrated a genetic relationship between our isolates (Iraqi isolates) and isolates from Indian and the United States. Conclusion: Our study indicated the widespread distribution of the enterotoxin gene A (SEA) of S. aureus among dairy cows. The molecular study revealed significant changes in key amino acids that could play an important role in the bacterium's pathogenesis. The phylogenetic similarities among S. aureus samples from various countries suggest that the bacteria has spread globally. [ABSTRACT FROM AUTHOR]

Bone infections caused by Staphylococcus aureus may lead to an inflammatory condition called osteomyelitis, which results in progressive bone loss. Biofilm formation, intracellular survival, and the ability of S. aureus to evade the immune response result in recurrent and persistent infections that present significant challenges in treating osteomyelitis. Moreover, people with diabetes are prone to osteomyelitis due to their compromised immune system, and in life-threatening cases, this may lead to amputation of the affected limbs. In most cases, bone infections are localized; thus, early detection and targeted therapy may prove fruitful in treating S. aureus-related bone infections and preventing the spread of the infection. Specific S. aureus components or overexpressed tissue biomarkers in bone infections could be targeted to deliver active therapeutics, thereby reducing drug dosage and systemic toxicity. Compounds like peptides and antibodies can specifically bind to S. aureus or overexpressed disease markers and combining these with therapeutics or imaging agents can facilitate targeted delivery to the site of infection. The effectiveness of photodynamic therapy and hyperthermia therapy can be increased by the addition of targeting molecules to these therapies enabling site-specific therapy delivery. Strategies like host-directed therapy focus on modulating the host immune mechanisms or signaling pathways utilized by S. aureus for therapeutic efficacy. Targeted therapeutic strategies in conjunction with standard surgical care could be potential treatment strategies for S. aureus-associated osteomyelitis to overcome antibiotic resistance and disease recurrence. This review paper presents information about the targeting strategies and agents for the therapy and diagnostic imaging of S. aureus bone infections. [ABSTRACT FROM AUTHOR]

The Asian region of earth has a rich agriculture system that provides extensive opportunities to boost pharmaceutical and nutritional research to address the use of food crops for health benefits and potential clinical applications. The traditionally cropped green leaf vegetable indigenously known as Bathu and botanically known as Chenopodium album (C. album) is traditionally used as a sedative, blood purifier, hepatoprotectant, diuretic, and antiscorbutic laxative. In this study, we investigated the anti-infection potential, anti-diabetic potential, and mineral composition of indigenously cultivated C. album plant extracts. Methanol and n-hexane solvents were used to extract phytochemicals at different extraction conditions. The maximum yield of 12.72 ± 0.36 g/100 g extract was obtained in methanol with 200 rpm shaking, 200 mL solvent, and an 8 h extraction period. Under the same conditions, n-hexane gave 2.09 ± 0.29 g/100 g extract. Good alpha-amylase inhibition efficiency was shown by the n-hexane extracts, while the methanol extracts showed good urease inhibition potential. The H6 extract had the lowest IC50 (8.16 ± 0.2 ug/mL) as compared to the standard acarbose (9.27 ± 0.6 ug/mL). Similarly, the M6 extract revealed a significant urease inhibitory potential, i.e., IC50 of 18.77 ± 0.6 ug/mL, which was close to the standard thiourea (IC50: 19.09 ± 0.7 ug/mL). Regarding the antibacterial study, the M6 extract showed 16.55 ± 0.57 mm ZOI against E. coli and 15.54 ± 0.55 mm in the case of S. aureus, as compared to the standard ciprofloxacin, which showed 26.08 ± 0.73 mm, and penicillin, which showed 21.12 ± 0.81 mm ZOI. Mineral profiling was investigated by ICP-OES, which showed significant amounts of Mg and Fe in all extracts. Our findings tend to show that systematic harvesting and utilization of this vegetable crop could be recommended as an alternative nutritional therapy in the management of internal infections and diabetes. [ABSTRACT FROM AUTHOR]

The development of new radiopharmaceuticals for the detection of hidden infection foci has great relevance for early detection and the selection of the correct treatment, particularly in immunosuppressed patients. In that sense, the labelling of antimicrobial peptides (AMPs) that are capable of binding specifically to the pathogenic microorganism which causes the infection, should provide a sufficiently specific agent, able to distinguish an infection from a sterile inflammation. Defensins are particularly interesting molecules with antimicrobial activity, the EcgDf1 defensin was identified from the genome of a Uruguayan native plant, Erythrina crista‐galli, the 'Ceibo' tree. Our group has previously reported a synthetic biologically active short analogue EcgDf21 (ERFTGGHCRGFRRRCFCTKHC) successfully labelled with 99mTc. Herein we present a shorter analogue which also preserves the γ‐core domain, as a pharmacophore for a potential infection detection agent. This peptide was derivatized with the bifunctional chelating agent 1,4,7‐triazacyclononane‐1,4,7‐triacetic acid (NOTA) through a lysine linker in the amino‐terminal group (NOTA‐KGHCRGFRRRC) and radiolabelled with 68Ga ([68Ga]Ga‐NOTA‐K‐EcgDf1(10)). The [68Ga]Ga‐NOTA‐K‐EcgDf1(10) labelling procedure rendered a product with high radiochemical purity and stability in the labelling milieu. The Log P value indicated that the complex has a hydrophilic behaviour, confirmed by the biodistribution profile. The [68Ga]Ga‐NOTA‐K‐EcgDf1(10) complex demonstrated specific binding to cultures of Candida albicans and Aspergillus niger. Its biodistribution showed renal elimination and low accumulation in the rest of the body. It was possible to successfully differentiate sterile inflammation from infection by PET images in nude mice with a target/non‐target ratio of 3.3 for C. albicans and 3.7 for A. niger, respectively. [ABSTRACT FROM AUTHOR]

A dual-recognition strategy is reported to construct a one-step washing and highly efficient signal-transduction tag system for high-sensitivity colorimetric detection of Staphylococcus aureus (S. aureus). The porous (gold core)@(platinum shell) nanozymes (Au@PtNEs) as the signal labels show highly efficient peroxidase mimetic activity and are robust. For the sake of simplicity the detection involved the use of a vancomycin-immobilized magnetic bead (MB) and aptamer-functionalized Au@PtNEs for dual-recognition detection in the presence of S. aureus. In addition, we designed a magnetic plate to fit the 96-well microplate to ensure consistent magnetic properties of each well, which can quickly remove unreacted Au@PtNEs and sample matrix while avoiding tedious washing steps. Subsequently, Au@PtNEs catalyze hydrogen peroxide (H2O2) to oxidize 3,3′,5,5′-tetramethylbenzidine (TMB) generating a color signal. Finally, the developed Au@PtNEs-based dual-recognition washing-free colorimetric assay displayed a response in the range of S. aureus of 5 × 101–5 × 105 CFU/mL, and the detection limit was 40 CFU/mL within 1.5 h. In addition, S. aureus-fortified samples were analyzed to further evaluate the performance of the proposed method, which yielded average recoveries ranging from 93.66 to 112.44% and coefficients of variation (CVs) within the range 2.72–9.01%. These results furnish a novel horizon for the exploitation of a different mode of recognition and inexpensive enzyme-free assay platforms as an alternative to traditional enzyme-based immunoassays for the detection of other Gram-positive pathogenic bacteria. [ABSTRACT FROM AUTHOR]

Importance: Bovine mastitis, predominantly associated with gram-positive Staphylococcus aureus, poses a significant threat to dairy cows, leading to a decline in milk quality and volume with substantial economic implications. Objective: This study investigated the incidence, virulence, and antibiotic resistance of S. aureus associated with mastitis in dairy cows. Methods: Fifty milk-productive cows underwent a subclinical mastitis diagnosis, and the S. aureus strains were isolated. Genomic DNA extraction, sequencing, and bioinformatic analysis were performed, supplemented by including 124 S. aureus genomes from cows with subclinical mastitis to enhance the overall analysis. Results: The results revealed a 42% prevalence of subclinical mastitis among the cows tested. Genomic analysis identified 26 sequence types (STs) for all isolates, with Mexican STs belonging primarily to CC1 and CC97. The analyzed genomes exhibited multidrug resistance to phenicol, fluoroquinolone, tetracycline, and cephalosporine, which are commonly used as the first line of treatment. Furthermore, a similar genomic virulence repertoire was observed across the genomes, encompassing the genes related to invasion, survival, pathogenesis, and iron uptake. In particular, the toxic shock syndrome toxin (tss-1) was found predominantly in the genomes isolated in this study, posing potential health risks, particularly in children. Conclusion and Relevance: These findings underscore the broad capacity for antibiotic resistance and pathogenicity by S. aureus, compromising the integrity of milk and dairy products. The study emphasizes the need to evaluate the effectiveness of antibiotics in combating S. aureus infections. [ABSTRACT FROM AUTHOR]

The present study aimed to isolate and identify Methicillin-Resistant DOIStaphylococcus aureus MRSA from the nasal cavity of healthy cows and buffaloes and their breeders in Nineveh Governorate and detect some virulence factors by using molecular methods. A total of 150 samples of cotton swabs were collected randomly from different areas of Nineveh governorate. The samples were cotton swabs from the nasal passages of healthy cattle, buffaloes, and their breeders (50 swabs of each type). All the samples were subjected to culture and molecular testing. The results showed the highest isolation percentage of S. aureus from cattle followed by breeders, then buffaloes, at 54%, 40%, and 32%, respectively. The total isolation percentage of MRSA was 65.1%. The highest percentage was in buffaloes, followed by breeders and cattle, at 93.75%, 70%, and 44.44%, respectively. Out of 41 isolates from cattle, buffaloes, and their breeders, the virulence genes clfA, clfB, and coa were detected in MRSA at rates of 100%, 80.49%, and 65.85%, respectively. The current study concluded that cattle and buffalo are considered carriers and potential transmitters of MRSA, which makes them risk factors for infection in humans, especially those who are in direct contact with animals. Together, these findings also highlight the need to prevent the transmission of zoonotic pathogens to humans via occupational exposure or consumption of contaminated animal products. [ABSTRACT FROM AUTHOR]

Immune activation is essential for lung control of viral and bacterial infection, but an overwhelming inflammatory response often leads to the onset of acute respiratory distress syndrome. IL-10 plays a crucial role in regulating the balance between antimicrobial immunity and immunopathology. In the present study, we investigated the role of IL-10 in acute lung injury induced by influenza A virus and methicillin-resistant Staphylococcus aureus coinfection. This unique coinfection model resembles patients with acute pneumonia undergoing appropriate antibiotic therapies. Using global IL-10 and IL-10 receptor gene-deficient mice, as well as in vivo neutralizing antibodies, we show that IL-10 deficiency promotes IFN-γ–dominant cytokine responses and triggers acute animal death. Interestingly, this extreme susceptibility is fully preventable by IFN-γ neutralization during coinfection. Further studies using mice with Il10ra deletion in selective myeloid subsets reveal that IL-10 primarily acts on mononuclear phagocytes to prevent IFN-γ/TNF-α hyperproduction and acute mortality. Importantly, this antiinflammatory IL-10 signaling is independent of its inhibitory effect on antiviral and antibacterial defense. Collectively, our results demonstrate a key mechanism of IL-10 in preventing hypercytokinemia and acute respiratory distress syndrome pathogenesis by counteracting the IFN-γ response. [ABSTRACT FROM AUTHOR]

The present study was done to know the In-vitro efficacy of Psidium guajava leaves against subclinical mastitis causing organisms namely S. aureus and E. coli. Total 200 cases of sub-clinical mastitis in buffaloes were screened from October 2020 to June 2021 in Ayodhya and Sultanpur districts of Uttar Pradesh by using California Mastitis Test (CMT) and White Side Test (WST). In-vitro efficacy of Psidium guajava extracts - Hydro/Aqueous (H), Methanolic (M) and Hydro-Methanolic (HM) extracts were studied by using disc diffusion sensitivity test and observed no inhibition zone for Hydro/Aqueous extract at any concentration for any bacteria. Hydro-Methanolic extract at 300 mg/ml concentration revealed inhibition zone against S. aureus only. Inhibition Zones for Methanolic extracts at 200 mg/ml, 250 mg/ml and 300 mg/ml were seen against S. aureus, maximum zone was obtained at 300 mg/ml and least against 200 mg/ml concentration. [ABSTRACT FROM AUTHOR]

Abstract Dayak tribes indigenous to the Indonesian island of Borneo has been using Bajakah Kalalawit (Uncaria gambir Roxb.) as traditional medicine for ages. This inspired us to develop phenolic from Bajakah Kalalawit extract as antibacterial agent. The extraction was done through decoction method and the determination of phenolic concentration was done using a visible spectrophotometer and Folin–Ciocalteu reagent (mixture of phosphotungstic and phosphomolybdic acids). We investigated the possibility of developing phenolic nanoparticle for future work. Kirby-Bauer method was used to assess antibacterial activity of phenolic against Staphylococcus aureus and the results were compared to Chloramphenicol in terms of its efficacy and duration of inhibition. This study contributes to the ongoing effort to address antibiotic resistance through the development of innovative antibacterial agents derived from natural sources. The results provide valuable insights into the potential of Bajakah Kalalawit phenolic extracts as a promising avenue for combating bacterial infections in the future.

Abstract Background Multi-drug resistant Staphylococcus aureus is one of the most common causes of nosocomial and community-acquired infections, with high morbidity and mortality. Treatment of such infections is particularly problematic; hence, it is complicated by antibiotic resistance, and there is currently no reliable vaccine. Furthermore, it is well known that S. aureus produces an exceptionally large number of virulence factors that worsen infection. Consequently, the urgent need for anti-virulent agents that inhibit biofilm formation and virulence factors has gained momentum. Therefore, we focused our attention on an already-approved antibiotic and explored whether changing the dosage would still result in the intended anti-virulence effect. Methods In the present study, we determined the antibiotic resistance patterns and the MICs of oxacillin against 70 MDR S. aureus isolates. We also investigated the effect of sub-MICs of oxacillin (at 1/4 and 1/8 MICs) on biofilm formation using the crystal violet assay, the phenol-sulphuric acid method, and confocal laser scanning microscopy (CLSM). We examined the effect of sub-MICs on virulence factors and bacterial morphology using quantitative reverse transcription polymerase chain reaction (qRT-PCR) and electron microscopy, respectively. Moreover, we studied the effect of sub-MICs of oxacillin (OX) in-vivo using a wound infection model. Results Oxacillin at 1/2 MIC showed a significant decrease in bacterial viability, while 1/4 and 1/8 MICs had negligible effects on treated bacterial isolates. Treatment of MDR isolates with 1/4 or 1/8 MICs of oxacillin significantly reduced biofilm formation (64% and 40%, respectively). The treated MDR S. aureus with sub-MICs of OX exhibited a dramatic reduction in several virulence factors, including protease, hemolysin, coagulase, and toxic shock syndrome toxin-1 (TSST-1) production. The sub-MICs of OX significantly decreased (P

Background: Although milk is nutritionally valuable, it also serves as a significant medium for the transmission of pathogens and their toxins. Aim: This study aimed to investigate the role of enterotoxin gene A (SEA) in the development of bovine mastitis. We accomplished this by examining milk through PCR testing, amino acid substitution analysis, and phylogenetic analysis. Methods: A total of fifty milk samples collected from locally bred dairy cows in Al-Diwaniyah, located in southern Iraq. We employed the VITEK-2 platform to validate the diagnosis of S. aureus and confirming the results of routine tests (culturing and biochemical tests). Subsequently, the genetic mutation and phylogeny analysis were achieved utilizing DNA sequencing to 16S rRNA and enterotoxin A genes. Results: 66% (33/50) of the milk samples found to be contain S. aureus by the VITEK-2 system. Furthermore, 25/33 of the samples were positive by the PCR test. While 60% (15 out of 25) tested positive for the SEA gene. After genomic analysis, we identified amino acid substitutions of serine, glutamine with arginine, tyrosine with cysteine, and aspartic acid with glycine at positions 9, 101, 119, 187, and 191. The phylogenetic investigation demonstrated a genetic relationship between our isolates (Iraqi isolates) and isolates from Indian and the United States. Conclusion: Our study indicated the widespread distribution of the enterotoxin gene A (SEA) of S. aureus among dairy cows. The molecular study revealed significant changes in key amino acids that could play an important role in the bacterium's pathogenesis. The phylogenetic similarities among S. aureus samples from various countries suggest that the bacteria has spread globally. [Open Vet J 2024; 14(7.000): 1644-1657]

Abstract Background Craniotomy is a common neurosurgery used to treat intracranial pathologies. Nearly 5% of the 14 million craniotomies performed worldwide each year become infected, most often with Staphylococcus aureus (S. aureus), which forms a biofilm on the surface of the resected bone segment to establish a chronic infection that is recalcitrant to antibiotics and immune-mediated clearance. Tumor necrosis factor (TNF), a prototypical proinflammatory cytokine, has been implicated in generating protective immunity to various infections. Although TNF is elevated during S. aureus craniotomy infection, its functional importance in regulating disease pathogenesis has not been explored. Methods A mouse model of S. aureus craniotomy infection was used to investigate the functional importance of TNF signaling using TNF, TNFR1, and TNFR2 knockout (KO) mice by quantifying bacterial burden, immune infiltrates, inflammatory mediators, and transcriptional changes by RNA-seq. Complementary experiments examined neutrophil extracellular trap formation, leukocyte apoptosis, phagocytosis, and bactericidal activity. Results TNF transiently regulated neutrophil and granulocytic myeloid-derived suppressor cell recruitment to the brain, subcutaneous galea, and bone flap as evident by significant reductions in both cell types between days 7 to 14 post-infection coinciding with significant decreases in several chemokines, which recovered to wild type levels by day 28. Despite these defects, bacterial burdens were similar in TNF KO and WT mice. RNA-seq revealed enhanced lymphotoxin-α (Lta) expression in TNF KO granulocytes. Since both TNF and LTα signal through TNFR1 and TNFR2, KO mice for each receptor were examined to assess potential redundancy; however, neither strain had any impact on S. aureus burden. In vitro studies revealed that TNF loss selectively altered macrophage responses to S. aureus since TNF KO macrophages displayed significant reductions in phagocytosis, apoptosis, IL-6 production, and bactericidal activity in response to live S. aureus, whereas granulocytes were not affected. Conclusion These findings implicate TNF in modulating granulocyte recruitment during acute craniotomy infection via secondary effects on chemokine production and identify macrophages as a key cellular target of TNF action. However, the lack of changes in bacterial burden in TNF KO animals suggests the involvement of additional signals that dictate S. aureus pathogenesis during craniotomy infection.

The present study aimed to isolate and identify Methicillin-Resistant Staphylococcus aureus MRSA from the nasal cavity of healthy cows and buffaloes and their breeders in Nineveh Governorate and detect some virulence factors by using molecular methods. A total of 150 samples of cotton swabs were collected randomly from different areas of Nineveh governorate. The samples were cotton swabs from the nasal passages of healthy cattle, buffaloes, and their breeders (50 swabs of each type). All the samples were subjected to culture and molecular testing. The results showed the highest isolation percentage of S. aureus from cattle followed by breeders, then buffaloes, at 54%, 40%, and 32%, respectively. The total isolation percentage of MRSA was 65.1%. The highest percentage was in buffaloes, followed by breeders and cattle, at 93.75%, 70%, and 44.44%, respectively. Out of 41 isolates from cattle, buffaloes, and their breeders, the virulence genes clfA, clfB, and coa were detected in MRSA at rates of 100%, 80.49%, and 65.85%, respectively. The current study concluded that cattle and buffalo are considered carriers and potential transmitters of MRSA, which makes them risk factors for infection in humans, especially those who are in direct contact with animals. Together, these findings also highlight the need to prevent the transmission of zoonotic pathogens to humans via occupational exposure or consumption of contaminated animal products.

Abstract Nasally colonized staphylococci carry antibiotic resistance genes and may lead to serious opportunistic infections. We are investigating nasal carriage of Staphylococcus aureus and Staphylococci other than S. aureus (SOSA) among young volunteers in Egypt to determine their risk potential. Nasal swabs collected over 1 week in June 2019 from 196 volunteers were cultured for staphylococcus isolation. The participants were interviewed to assess sex, age, general health, hospitalization and personal hygiene habits. Identification was carried out using biochemical tests and VITEK 2 automated system. Disc diffusion and minimum inhibitory concentration tests were performed to determine antibiotic susceptibility. Screening for macrolide resistance genes (ermA, ermB, ermC, ermT and msrA) was performed using polymerase chain reaction. Thirty four S. aureus and 69 SOSA were obtained. Multi-drug resistance (MDR) was detected among most staphylococcal species, ranging from 30.77% among S. hominis to 50% among S. epidermidis. Phenotypic resistance to all tested antibiotics, except for linezolid, was observed. Susceptibility to rifampicin, vancomycin and teicoplanin was highest. ermB showed the highest prevalence among all species (79.41% and 94.2% among S. aureus and SOSA, respectively), and constitutive macrolide-lincosamide-streptogramin B (MLSB) resistance was equally observed in S. aureus and SOSA (11.11% and 16.22%, respectively), whereas inducible MLSB resistance was more often found in S. aureus (77.78% and 43.24%, respectively). The species or resistance level of the carried isolates were not significantly associated with previous hospitalization or underlying diseases. Although over all colonization and carriage of resistance genes are within normal ranges, the increased carriage of MDR S. aureus is alarming. Also, the fact that many macrolide resitance genes were detected should be a warning sign, particularly in case of MLSB inducible phenotype. More in depth analysis using whole genome sequencing would give a better insight into the MDR staphylococci in the community in Egypt.

Abstract The purpose of this study was to evaluate antibacterial activity of pigment extracted from bacteria, isolated from soil samples. During the study, 20 soil samples were collected from different areas (forest, agriculture fields, river sides and dumping sites) of Kathmandu and Lalitpur districts which were processed for isolation of pigment producing bacteria by spread plate technique. The pigmented bacterial isolates were identified and enriched in nutrient broth. Then, pigment was extracted in 95% methanol as solvent, which was further characterized using UV-Vis Spectrophotometric and TLC analysis. The obtained crude pigment extract was processed to carry out the antimicrobial susceptibility assay using agar well diffusion method. Out of 13 total pigmented bacteria isolates, four different colored pigmented bacterial isolates (S4O, S11Y, S14P and S17G) which produced efficient pigment on nutrient agar were chosen and they were further processed. Among these isolates, S4O was identified as Staphylococcus aureus, S11Y was identified as Micrococcus luteus, S14P was identified as Micrococcus roseus and S17G was identified as Pseudomonas aeruginosa respectively. On characterization using UV-Vis Spectrophotometric and TLC analysis, the pigment extracted from isolates S4O, S11Y and S14P were found to be Carotenoids and from isolate S17G was found to be Pyocyanin in nature. The maximum antibacterial activity was shown against Staphylococcus aureus from all the four pigments extracts. The green color pigment extract from isolate S17G was found to be most effective against all the Gram-positive and Gram-negative test bacteria. This study suggests that these pigment extracts from pigmented bacteria may have beneficial antibacterial roles that can be exploited in controlling unwanted bacterial growth.

The present study sought to perform antibacterial screening of the Lubeg leaf extracts derived from a 12-year Lubeg Plantation at Apayao State College, Payanan, San Gregorio, Luna, Apayao, against Escherichia coli and Staphylococcus aureus. The antimicrobial activity was evaluated using the disk diffusion method. The 100% Lubeg leaf extracts exhibited the highest mean zone of inhibition against E. coli after 20 hours while after 30 hours of incubation, the 50% Lubeg leaf extracts exhibited the highest mean zone of inhibition and active antibacterial activity against E. coli. Meanwhile, the 25% Lubeg leaf extracts exhibited the highest mean zone of inhibition and active antibacterial activity against S. aureus for both 20 hours and 30 hours of incubation. The Lubeg leaf extract has potential antimicrobial activities against these two bacterial strains, revealing its high potential as an antibacterial agent.

Abstract Background Staphylococcus aureus can colonize and infect a variety of animal species. In dairy herds, it is one of the leading causes of mastitis cases. The objective of this study was to characterize the S. aureus isolates recovered from nasal swabs of 249 healthy cows and 21 breeders of 21 dairy farms located in two provinces of Algeria (Tizi Ouzou and Bouira). Methods The detection of enterotoxin genes was investigated by multiplex PCRs. Resistance of recovered isolates to 8 antimicrobial agents was determined by disc-diffusion method. The slime production and biofilm formation of S. aureus isolates were assessed using congo-red agar (CRA) and microtiter-plate assay. Molecular characterization of selected isolates was carried out by spa-typing and Multi-Locus-Sequence-Typing (MLST). Results S. aureus was detected in 30/249 (12%) and 6/13 (28.6%) of nasal swabs in cows and breeders, respectively, and a total of 72 isolates were recovered from positive samples (59 isolates from cows and 13 from breeders). Twenty-six of these isolates (36.1%) harbored genes encoding for staphylococcal enterotoxins, including 17/59 (28.8%) isolates from cows and 9/13 (69.2%) from breeders. Moreover, 49.1% and 92.3% of isolates from cows and breeders, respectively, showed penicillin resistance. All isolates were considered as methicillin-susceptible (MSSA). Forty-five (76.3%) of the isolates from cows were slime producers and 52 (88.1%) of them had the ability to form biofilm in microtiter plates. Evidence of a possible zoonotic transmission was observed in two farms, since S. aureus isolates recovered in these farms from cows and breeders belonged to the same clonal lineage (CC15-ST15-t084 or CC30-ST34-t2228). Conclusions Although healthy cows in this study did not harbor methicillin-resistant S. aureus isolates, the nares of healthy cows could be a reservoir of enterotoxigenic and biofilm producing isolates which could have implications in human and animal health.

Lactic acid bacteria (LAB) can produce peptides known as bacteriocins with antagonistic activity against foodborne pathogens. The potential of LAB isolated from the surface of jalapeno peppers to produce bacteriocins with antagonistic activity against Listeria monocytogenes, Staphylococcus aureus, Escherichia coli O157:H7, and Salmonella Typhimurium was evaluated. Previously isolated LAB strains were reactivated, and their cell-free supernatants (CFSs) were evaluated. Out of 390 reactivated strains, 60 produced bacteriocin-like inhibitory substances (BLIS) since their antagonistic activity was lost after proteases addition. Subsequently, 16 BLIS showed heat resistance (HR-BLIS), retaining their bioactivity after heat treatment (121 °C for 15 min). By 16S rRNA gene sequencing and antibiotic susceptibility tests, LAB strains producing HR-BLIS were identified as Enterococcus lactis. Four HR-BLIS exhibited a minimum inhibitory concentration (MIC) of 80 mg/mL against L. monocytogenes. MIC and minimum bactericidal concentration (MBC) of HR-BLIS-67 for S. aureus (MIC = 80 mg/mL; MBC = 320 mg/mL), S. Typhimurium (MIC = 150 mg/mL; MBC = 250 mg/mL), and E. coli O157:H7 (MIC = 250 mg/mL; MBC = 400 mg/mL) were determined. LAB isolated from the surface of jalapeno pepper produced HR-BLIS (possibly enterocin) that exhibited broad-spectrum antagonistic activity against foodborne pathogens; therefore, they are a promising source of natural antimicrobials to ensure food safety.

Abstract Background In dairy cattle, mastitis causes high financial losses and impairs animal well-being. Genetic selection is used to breed cows with reduced mastitis susceptibility. Techniques such as milk cell flow cytometry may improve early mastitis diagnosis. In a highly standardized in vivo infection model, 36 half-sib cows were selected for divergent paternal Bos taurus chromosome 18 haplotypes (Q vs. q) and challenged with Escherichia coli for 24 h or Staphylococcus aureus for 96 h, after which the samples were analyzed at 12 h intervals. Vaginal temperature (VT) was recorded every three minutes. The objective of this study was to compare the differential milk cell count (DMCC), milk parameters (fat %, protein %, lactose %, pH) and VT between favorable (Q) and unfavorable (q) haplotype cows using Bayesian models to evaluate their potential as improved early indicators of differential susceptibility to mastitis. Results After S. aureus challenge, compared to the Q half-sibship cows, the milk of the q cows exhibited higher PMN levels according to the DMCC (24 h, p

Objective: This study focused on the antibiogram profiling of Staphylococcus aureus and coagu¬lase-negative Staphylococcus spp. (CoNS) and the detection of icaA and blaZ genes from bovine raw milk samples. Materials and Methods: Bovine milk samples were collected from dairy farms, and Staphylococcus spp. were isolated and identified via conventional and molecular screening. Disk diffusion test (DDT) was implemented to determine the resistance pattern. Biofilm and β-lactamase-produc¬ing Staphylococcus spp. were identified via amplification of the icaA and blaZ genes. Methicillin-resistant Staphylococcus aureus and CoNS were identified by DDT and PCR of the mecA gene. Results: From 63 samples, 35 were confirmed as Staphylococcus spp., of which 16 (25.39%) S. aureus isolates were coagulase-positive, while 19 (30.16%) were negative. PCR confirmed that 50% (8/16) of S. aureus and 36.84% (7/19) of CoNS possessed the icaA gene. All S. aureus iso¬lates were found resistant to penicillin-G (P) both phenotypically and genotypically. The isolates were also resistant to erythromycin (ERY) and oxytetracycline (TET). While CoNS showed high to reduced resistance against P, TET, ERY, and azithromycin, no S. aureus isolates were resistant to sulfamethoxazole, while 10.53% of CoNS isolates were. All S. aureus and CoNS isolates were sus¬ceptible to vancomycin and gentamicin. MR was exhibited by 37.5% of S. aureus and 42.10% of CoNS isolates. Moreover, S. aureus and CoNS had 56.25% and 52.63% multidrug-resistant (MDR) isolates, respectively. Conclusion: The present study revealed the presence of a biofilm-producing, MDR staphylococcal strain in milk that might endanger consumers. Routine surveillance and monitoring, along with antimicrobial resistance learning, can reduce risks. [J Adv Vet Anim Res 2024; 11(2.000): 455-462]

Staphylococcus aureus (S. aureus) merupakan golongan bakteri koagulase positif yang menyebabkan berbagai macam penyakit klinis pada manusia dan hewan. Determinasi pola gen coa merupakan salah satu metode yang sering digunakan dalam lingkup studi epidemiologi S. aureus. Penelitian ini dilakukan untuk membandingkan metode coa polymorphism dan coa typing pada isolat S. aureus yang diisolasi dari sumber berbeda. Tujuh belas koleksi isolat S. aureus asal susu pasteurisasi, susu mastitis kambing peranakan etawa, dan daging ayam segar ditumbuhkan dari stok gliserol -80oC, kemudian dilakukan ekstraksi DNA dan amplifikasi gen penyandi koagulase (coa) dengan teknik PCR menggunakan primer untuk coa polymorphism dan coa typing. Diketahui, level diskriminasi coa typing lebih variatif dibandingkan dengan coa polymorphism pada 17 isolat yang diuji. Metode coa typing menunjukkan 7 tipe berbeda, sedangkan coa polymorphism hanya 3. Empat dari 17 isolat tidak dapat ditentukan coa typing, menunjukkan potensi pengembangan tipe baru coa typing untuk isolat-isolat asal Indonesia, untuk kepentingan studi epidemiologi.

Malarmugila Manimaran,1,&ast; Yin Yin Teo,2 James Chen Yong Kah,3 Adilet Beishenaliev,1 Yean Leng Loke,2 Yiing Yee Foo,1 Shiow-Fern Ng,4 Chin Fei Chee,5 Sek Peng Chin,6 Farid Nazer Faruqu,1 Chia-Yu Chang,7 Misni Misran,2 Lip Yong Chung,6 Bey Fen Leo,8,&ast; Shih-Hwa Chiou,9,10 Chia-Ching Chang,7,11– 13 Sun Tee Tay,14 Lik Voon Kiew1,7 1Department of Pharmacology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia; 2Department of Chemistry, Faculty of Science, Universiti Malaya, Kuala Lumpur, Malaysia; 3Department of Biomedical Engineering, College of Design and Engineering, National University of Singapore, Singapore, Singapore; 4Centre for Drug Delivery Technology and Vaccine, Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia; 5Nanotechnology Catalysis Research Centre, Universiti Malaya, Kuala Lumpur, Malaysia; 6Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Universiti Malaya, Kuala Lumpur, Malaysia; 7Department of Biological Science and Technology, National Yang Ming Chiao Tung University, Hsinchu, Taiwan, Republic of China; 8Department of Molecular Medicine, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia; 9Department of Medical Research, Taipei Veterans General Hospital, Taipei, Taiwan, Republic of China; 10Institute of Pharmacology, National Yang Ming Chiao Tung University, Taipei, Taiwan, Republic of China; 11Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu, Taiwan, Republic of China; 12Center for Intelligent Drug Systems and Smart Bio-devices, National Yang Ming Chiao Tung University, Hsinchu, Taiwan, Republic of China; 13Institute of Physics, Academia Sinica, Nankang, Taipei, Taiwan, Republic of China; 14Department of Medical Microbiology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia&ast;These authors contributed equally to this workCorrespondence: Chia-Ching Chang; Lik Voon Kiew, Email ccchang01@nycu.edu.tw; lvkiew@um.edu.myIntroduction: Over 75% of clinical microbiological infections are caused by bacterial biofilms that grow on wounds or implantable medical devices. This work describes the development of a new poly(diallyldimethylammonium chloride) (PDADMAC)/alginate-coated gold nanorod (GNR/Alg/PDADMAC) that effectively disintegrates the biofilms of Staphylococcus aureus (S. aureus), a prominent pathogen responsible for hospital-acquired infections.Methods: GNR was synthesised via seed-mediated growth method, and the resulting nanoparticles were coated first with Alg and then PDADMAC. FTIR, zeta potential, transmission electron microscopy, and UV–Vis spectrophotometry analysis were performed to characterise the nanoparticles. The efficacy and speed of the non-coated GNR and GNR/Alg/PDADMAC in disintegrating S. aureus-preformed biofilms, as well as their in vitro biocompatibility (L929 murine fibroblast) were then studied.Results: The synthesised GNR/Alg/PDADMAC (mean length: 55.71 ± 1.15 nm, mean width: 23.70 ± 1.13 nm, aspect ratio: 2.35) was biocompatible and potent in eradicating preformed biofilms of methicillin-resistant (MRSA) and methicillin-susceptible S. aureus (MSSA) when compared to triclosan, an antiseptic used for disinfecting S. aureus colonisation on abiotic surfaces in the hospital. The minimum biofilm eradication concentrations of GNR/Alg/PDADMAC (MBEC50 for MRSA biofilm = 0.029 nM; MBEC50 for MSSA biofilm = 0.032 nM) were significantly lower than those of triclosan (MBEC50 for MRSA biofilm = 10,784 nM; MBEC50 for MRSA biofilm 5967 nM). Moreover, GNR/Alg/PDADMAC was effective in eradicating 50% of MRSA and MSSA biofilms within 17 min when used at a low concentration (0.15 nM), similar to triclosan at a much higher concentration (50 μM). Disintegration of MRSA and MSSA biofilms was confirmed by field emission scanning electron microscopy and confocal laser scanning microscopy.Conclusion: These findings support the potential application of GNR/Alg/PDADMAC as an alternative agent to conventional antiseptics and antibiotics for the eradication of medically important MRSA and MSSA biofilms.Keywords: biofilm, gold nanorod, S. aureus, PDADMAC, MRSA, MSSA

Abstract Various studies have shown that natural colorants, in addition to their coloring attributes, have valuable biological effects such as antioxidant, anti‐inflammation, and anticarcinogenic properties. Moreover, their use as a food colorant can restrict the potential disadvantages of synthetic additives and turn foods into functional products. In this study, in vitro antimicrobial activities of two natural colorants of bixin and curcumin against some important foodborne pathogens: Staphylococcus aureus (S. aureus), Listeria innocua (L. innocua), and Escherichia coli (E. coli) were investigated by disk diffusion method. Minimum inhibitory concentration and minimum bactericidal concentration values were determined by agar dilution and broth microdilution methods. The synergistic activity of the colorants against selected microorganisms was assayed by the checkerboard microdilution method. The results showed that the inhibitory effects of bixin against S. aureus were more pronounced than E. coli and L. innocua. The lowest concentration of curcumin (0.6 mg/mL) in the disk diffusion method was not inhibited by any tested bacteria. However, it was effective at the higher concentrations against three microorganisms, but its diameter of inhibition zones was lower than gentamicin in all concentrations. Synergetic effects were observed by curcumin and bixin combination against S. aureus (FICI ≤ 0.5), but they act as an antagonist against E. coli and L. innocua. The results of the synergy test were confirmed by the isobologram curves.

Nasally colonized staphylococci carry antibiotic resistance genes and may lead to serious opportunistic infections. We are investigating nasal carriage of Staphylococcus aureus and Staphylococci other than S. aureus (SOSA) among young volunteers in Egypt to determine their risk potential. Nasal swabs collected over 1 week in June 2019 from 196 volunteers were cultured for staphylococcus isolation. The participants were interviewed to assess sex, age, general health, hospitalization and personal hygiene habits. Identification was carried out using biochemical tests and VITEK 2 automated system. Disc diffusion and minimum inhibitory concentration tests were performed to determine antibiotic susceptibility. Screening for macrolide resistance genes (ermA, ermB, ermC, ermT and msrA) was performed using polymerase chain reaction. Thirty four S. aureus and 69 SOSA were obtained. Multi-drug resistance (MDR) was detected among most staphylococcal species, ranging from 30.77% among S. hominis to 50% among S. epidermidis. Phenotypic resistance to all tested antibiotics, except for linezolid, was observed. Susceptibility to rifampicin, vancomycin and teicoplanin was highest. ermB showed the highest prevalence among all species (79.41% and 94.2% among S. aureus and SOSA, respectively), and constitutive macrolide-lincosamide-streptogramin B (MLSB) resistance was equally observed in S. aureus and SOSA (11.11% and 16.22%, respectively), whereas inducible MLSB resistance was more often found in S. aureus (77.78% and 43.24%, respectively). The species or resistance level of the carried isolates were not significantly associated with previous hospitalization or underlying diseases. Although over all colonization and carriage of resistance genes are within normal ranges, the increased carriage of MDR S. aureus is alarming. Also, the fact that many macrolide resitance genes were detected should be a warning sign, particularly in case of MLSB inducible phenotype. More in depth analysis using whole genome sequencing would give a better insight into the MDR staphylococci in the community in Egypt. [ABSTRACT FROM AUTHOR]