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Antimicrobial resistance is a global concern, far from being resolved. The need of new drugs against new targets is imminent. In this work, we present a family of aminoalkyl resveratrol derivatives with antibacterial activity inspired by the properties of cationic amphipathic antimicrobial peptides. Surprisingly, the newly designed molecules display modest activity against aerobically growing bacteria but show surprisingly good antimicrobial activity against anaerobic bacteria (Gram-negative and Gram-positive) suggesting specificity towards this bacterial group. Preliminary studies into the action mechanism suggest that activity takes place at the membrane level, while no cross-resistance with traditional antibiotics is observed. Actually, some good synergistic relations with existing antibiotics were found against Gram-negative pathogens. However, some cytotoxicity was observed, despite their low haemolytic activity. Our results show the importance of the balance between positively charged moieties and hydrophobicity to improve antimicrobial activity, setting the stage for the design of new drugs based on these molecules.

Mechanical properties of bacterial colonies are crucial considering both addressing their pathogenic effects and exploring their potential applications. Viscoelasticity is a key mechanical property with major impacts on the cell shapes and functions, which reflects the information about the cell envelope constituents. Hereby, we have proposed the application of photoacoustic viscoelasticity (PAVE) for studying the rheological properties of bacterial colonies. In this regard, we employed an intensity-modulated laser beam as the excitation source followed by the phase delay measurement between the generated PA signal and the reference for the characterization of colonies of two different types of Gram-positive and Gram-negative bacteria. The results of our study show that the colony of Staphylococcus aureus as Gram-positive bacteria has a significantly higher viscoelasticity ratio compared to that value for Acinetobacter baumannii as Gram-negative bacteria (77% difference). This may be due to the differing cell envelope structure between the two species, but we cannot rule out effects of biofilm formation in the colonies. Furthermore, a lumped model has been provided for the mechanical properties of bacterial colonies., (© 2023. Springer Nature Limited.)

Objective: Bacteria identification inside the dental tissue is a complex procedure requiring specific protocols. This study aimed to compare two classical Gram staining methods with a new staining method proposed by the authors to detect Gram-positive and Gram-negative bacteria in dental histological samples of human dentin., Methods: Ten human teeth, extracted because of various pathologies, were decalcified, dehydrated, and paraffin-embedded. Then, approximately 100 serial sections of 4 µm thickness were made per sample. The serial sections were placed on glass slides and were stained according to Brown-Brenn, Brown-Hopps, and a proposed modification of Brown-Brenn staining. Both ATCC strains, smeared on glass slides, were stained following each method's instructions used in histological samples., Results: From a qualitative evaluation, the Brown-Brenn method resulted in better staining of Gram-positive bacteria, while the authors' proposed staining technique was more oriented towards Gram-negative bacteria. On the other hand, the Brown-Hopps showed quite a balance in detecting Gram-positive and Gram-negative bacteria. Unlike the Brown-Brenn stain, the other two protocols showed better stainability of Gram-negative microorganisms in bacterial-smeared samples., Conclusion: All staining techniques evaluated in this article can identify bacteria, but the outcome can change according to the staining procedure used., Competing Interests: Conflict of Interests The authors declare that no conflicts of interest are associated with this manuscript., (Copyright © 2022 Elsevier GmbH. All rights reserved.)

Pathogenic bacteria possess a great potential of causing infectious diseases and represent a serious threat to human and animal health. Understanding the molecular basis of infection development can provide new valuable strategies for disease prevention and better control. In host-pathogen interactions, actin-cytoskeletal dynamics play a crucial role in the successful adherence, invasion, and intracellular motility of many intruding microbial pathogens. Cortactin, a major cellular factor that promotes actin polymerization and other functions, appears as a central regulator of host-pathogen interactions and different human diseases including cancer development. Various important microbes have been reported to hijack cortactin signaling during infection. The primary regulation of cortactin appears to proceed via serine and/or tyrosine phosphorylation events by upstream kinases, acetylation, and interaction with various other host proteins, including the Arp2/3 complex, filamentous actin, the actin nucleation promoting factor N-WASP, focal adhesion kinase FAK, the large GTPase dynamin-2, the guanine nucleotide exchange factor Vav2, and the actin-stabilizing protein CD2AP. Given that many signaling factors can affect cortactin activities, several microbes target certain unique pathways, while also sharing some common features. Here we review our current knowledge of the hallmarks of cortactin as a major target for eminent Gram-negative and Gram-positive bacterial pathogens in humans., (© 2022 The Authors. Molecular Microbiology published by John Wiley & Sons Ltd.)

The unique structural components of cell membranes of Gram-positive bacteria, Gram-negative bacteria, and mycobacteria provide an excellent therapeutic target for developing highly specific antimicrobials. Here, we report the synthesis of nine cholic acid (CA)-derived amphiphiles, where three hydroxyl groups of CA were tethered to dimethylamino pyridine and the C24-carboxyl group was conjugated with different alkyl chains. Structure-activity investigations revealed that amphiphile 1 harboring a methyl group has antimicrobial activity against mycobacterial species. On the other hand, amphiphile 7 containing an octyl chain was selective against Gram-positive and Gram-negative bacilli. Biochemical assays confirmed the selective membrane permeabilization abilities of amphiphiles 1 and 7 . Importantly, we demonstrate the selective actions of amphiphiles in clearing biofilms, intracellular bacteria, and wound infections. Therefore, for the first time, we show that the unique structural features of CA-derived amphiphiles dictate selective activity against specific bacterial species.

Background: External eye infection caused by bacteria can lead to reduced vision and blindness. Therefore, pathogen isolation and antimicrobial susceptibility testing are vital for the prevention and control of ocular diseases., Objective: The main aim of this study was to assess bacterial isolates, their antimicrobial susceptibility pattern, and associated factors of external ocular infection (EOI) among patients attended eye clinic at Debre Markos Comprehensive Specialized Hospital (DMCSH), Northwest Ethiopia., Methods: We conducted a cross-sectional study in patients with external ocular infections from January 1, 2021, to June 30, 2021, at DMCSH. Socio-demographic and clinical data were collected using semi-structured questionnaires. Following standard protocols, external ocular swabs were collected and inoculated onto blood agar, chocolate agar, MacConkey agar and mannitol salt agar (MSA). Finally, bacterial isolates were identified by Gram stain, colony morphology, and biochemical tests. Antimicrobial susceptibility testing was done by using the modified Kirby-Bauer disk diffusion technique according to Clinical and Laboratory Standards Institute (CLSI) guideline. Cleaned and coded data were entered into EpiData version 4.2 software and exported to Statistical Packages for Social Sciences (SPSS) version 22 for analysis. Bivariate logistic regression was applied to investigate the association between predictors and outcome variables. P-values ≤ 0.05 with 95% confidence interval were considered statistically significant., Results: Two hundred seven study participants were enrolled in this study. More than half of them (57.5%, 119/207) were males, and 37.7% (78/207) of them were ≥ 65 years old. A total of 130 (62.8%) bacterial isolates were identified, with Gram-positive bacteria accounting for 78.5% (102/130) of the isolates. Staphylococcus aureus was the most common isolate with a 46.2% (60/130) prevalence. Ciprofloxacin was comparatively effective against Gram-positive and Gram-negative bacteria. The prevalence of culture-confirmed bacteria was significantly associated with age groups 15-24 (AOR: 9.18, 95%CI: 1.01-82.80; P = 0.049) and 25-64 (AOR: 7.47, 95%CI: 1.06-52.31; P = 0.043). Being farmer (AOR: 5.33, 95% CI: 1.04-37.33; P = 0.045), previous history of eye surgery (AOR: 5.39, 95% CI: 1.66-17.48; P = 0.005), less frequency of face washing (AOR: 5.32, 95% CI: 1.31-7.23; P = 0.010) and face washing once a day (AOR: 3.07, 95% CI: 1.13-25.13; P = 0.035) were also significantly associated with the prevalence of culture-confirmed bacteria., Conclusion: The prevalence of culture-confirmed bacteria among patients with EOI was high in the study area. A considerable proportion of bacterial isolates exhibited mono and/or multi-drug resistance. Age (15-64 years), being farmer, previous history of eye surgery and less frequency of face washing were significantly associated with the prevalence of culture-confirmed bacteria. Bacterial isolation and antibiotic susceptibility testing should be routinely performed in the study area to combat the emergence of antibiotic resistance., Competing Interests: The authors have declared that no competing interests exist.

Background: The turnover time of positive blood culture using traditional methods takes too long. This study aimed to evaluate rapid direct identification and drug sensitivity test methods for pathogens in positive blood cultures., Methods: A total of 403 blood culture bottles were used to compare the rapid identification methods and drug sensitivity tests for pathogens causing bloodstream infections. Bacteria were enriched using separator gel tubes and were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. In addition, bacteria were also identified using an established traditional method for comparison. The sensitivity of gram-negative bacilli against antibiotics was tested using Rapid Bacterial Test Strips or the VITEK 2 Compact system., Results: The accuracy was 81.8% in 403 bacteria, of which 71% (132/186) and 96.3% (209/217) were gram-positive and gram-negative bacteria, respectively. The gram-positive bacteria were primarily Staphylococcus aureus and coagulase-negative Staphylococcus. The gram-negative bacteria were primarily Escherichia coli and Klebsiella pneumonia. Compared with routine drug sensitivity testing methods, the coincidence rate of direct drug sensitivity testing for classifying the bacteria was 98.6% (1,325/1,344). The average rapid bacterial identification time was 1.5 hours, and the direct drug sensitivity test took - 8.5 hours., Conclusions: The present study showed that direct identification and rapid drug sensitivity testing can be performed on the same day and can be completed 1 or 2 days ahead of routine methods, thereby assisting in providing earlier drug options for anti-infective therapy.

Thieno[2,3-d]pyrimidines represent a novel antibacterial prodrug scaffold, previously identified through a screening campaign against Mycobacterium tuberculosis in which the formation of highly antimycobacterial metabolites catalyzed by the nitroreductase Mrx2 is suggested to be the relevant killing mechanism. As analogous activation pathways may also be employed in other prokaryotes, in this work we explored general antibacterial effects of this compound class. Through exploration of the chemical space by different synthetic strategies, 51 novel derivatives were generated, biologically evaluated and thus enabled initial conclusions about structure-activity relationships. Remarkably, anti-Gram-positive activity can be well modulated, particularly towards Staphylococci (MRSA) and even slightly against some Gram-negative strains. The two most promising hit compounds showed good pharmacokinetic properties in vitro as well as acceptable toxicity in HeLa cells, qualifying them as starting points for lead-generation campaigns., (© 2022 Wiley-VCH GmbH.)

With the increasing incidence of antibiotic resistance, there is an urgent need to develop new antibiotics with excellent activity against drug-resistant bacteria. Three novel series of tylosin semisynthetic derivatives were designed, synthesized and evaluated for their antibacterial activities against various Gram-positive and Gram-negative bacteria. Among these derivatives, compound C-2 demonstrated potent antibacterial activity against both gram-positive and gram negative bacteria, and non mutagenic. More importantly, compound C-2 displayed high antimicrobial potency against Gram-positive bacteria in a murine model, and was found to be more efficient than tildipirosin. Thus, compound C-2 had great potential as a promising lead compound for the treatment of bacterial infection., (Copyright © 2022 Elsevier Masson SAS. All rights reserved.)

The alarming rise of bacterial antibiotic resistance requires the development of new compounds. Such compounds, lipophosphonoxins (LPPOs), were previously reported to be active against numerous bacterial species, but serum albumins abolished their activity. Here we describe the synthesis and evaluation of novel antibacterial compounds termed LEGO-LPPOs, loosely based on LPPOs, consisting of a central linker module with two attached connector modules on either side. The connector modules are then decorated with polar and hydrophobic modules. We performed an extensive structure-activity relationship study by varying the length of the linker and hydrophobic modules. The best compounds were active against both Gram-negative and Gram-positive species including multiresistant strains and persisters. LEGO-LPPOs act by first depleting the membrane potential and then creating pores in the cytoplasmic membrane. Importantly, their efficacy is not affected by the presence of serum albumins. Low cytotoxicity and low propensity for resistance development demonstrate their potential for therapeutic use.

Infections caused by drug-resistant bacteria are a serious threat to public health worldwide, and the discovery of novel antibacterial compounds is urgently needed. Here, we screened an FDA-approved small-molecule library and found that crizotinib possesses good antimicrobial efficacy against Gram-positive bacteria. Crizotinib was found to increase the survival rate of mice infected with bacteria and decrease pulmonary inflammation activity in an animal model. Furthermore, it showed synergy with clindamycin and gentamicin. Importantly, the Gram-positive bacteria showed a low tendency to develop resistance to crizotinib. Mechanistically, quantitative proteomics and biochemical validation experiments indicated that crizotinib exerted its antibacterial effects by reducing ATP production and pyrimidine metabolism. A drug affinity responsive target stability study suggested crizotinib targets the CTP synthase PyrG, which subsequently disturbs pyrimidine metabolism and eventually reduces DNA synthesis. Subsequent molecular dynamics analysis showed that crizotinib binding occurs in close proximity to the ATP binding pocket of PyrG and causes loss of function of this CTP synthase. Crizotinib is a promising antimicrobial agent and provides a novel choice for the development of treatment for Gram-positive infections. IMPORTANCE Infections caused by drug-resistant bacteria are a serious problem worldwide. Therefore, there is an urgent need to find novel drugs with good antibacterial activity against multidrug-resistant bacteria. In this study, we found that a repurposed drug, crizotinib, exhibits excellent antibacterial activity against drug-resistant bacteria both in vivo and in vitro via suppressing ATP production and pyrimidine metabolism. Crizotinib was found to disturb pyrimidine metabolism by targeting the CTP synthase PyrG, thus reducing DNA synthesis. This unique mechanism of action may explain the decreased development of resistance by Staphylococcus aureus to crizotinib. This study provides a potential option for the treatment of drug-resistant bacterial infections in the future.

In the era of antimicrobial resistance, the identification of new compounds with strong antimicrobial activity and the development of alternative therapies to fight drug-resistant bacteria are urgently needed. Here, we have used resveratrol, a safe and well-known plant-derived stilbene with poor antimicrobial properties, as a scaffold to design several new families of antimicrobials by adding different chemical entities at specific positions. We have characterized the mode of action of the most active compounds prepared and have examined their synergistic antibacterial activity in combination with traditional antibiotics. Some alkyl- and silyl-resveratrol derivatives show bactericidal activity against Gram-positive bacteria in the same low micromolar range of traditional antibiotics, with an original mechanism of action that combines membrane permeability activity with ionophore-related activities. No cross-resistance or antagonistic effect was observed with traditional antibiotics. Synergism was observed for some specific general-use antibiotics, such as aminoglycosides and cationic antimicrobial peptide antibiotics. No hemolytic activity was observed at the active concentrations or above, although some low toxicity against an MRC-5 cell line was noted.

In this study, we perform a thermal curve analysis with terahertz (THz) metamaterials to develop a label-free identification tool for pathogens such as bacteria and yeasts. The resonant frequency of the metasensor coated with a bacterial layer changes as a function of temperature; this provides a unique fingerprint specific to the individual microbial species without the use of fluorescent dyes and antibodies. Differential thermal curves obtained from the temperature-dependent resonance exhibit the peaks consistent with bacterial phases, such as growth, thermal inactivation, DNA denaturation, and cell wall destruction. In addition, we can distinguish gram-negative bacteria from gram-positive bacteria which show strong peaks in the temperature range of cell wall destruction. Finally, we perform THz melting curve analysis on the mixture of bacterial species in which the pathogenic bacteria are successfully distinguished from each other, which is essential for practical clinical and environmental applications such as in blood culture., (© 2022. The Author(s).)

Extracellular vesicles (EVs), also known as membrane vesicles, are vesicular bodies secreted by eukaryotic cells and bacteria. EVs can carry proteins, DNA, RNA, and various metabolites for the exchange and transmission of substances between cells. They play contents-dependent physiological functions, such as delivering nutrients, participating in immune response, and treating cancers. Currently, most studies focus on the exploration of vesicles secreted by eukaryotic cells and gram-negative bacteria, while few studies focus on gram-positive bacteria. This review summarized the production, content composition, physiological function, and engineering of EVs secreted by gram-positive bacteria, and prospected future perspectives in this area.

The efficient regioselective bromination and iodination of the nonsteroidal anti-inflammatory drug (NSAID) carprofen were achieved by using bromine and iodine monochloride in glacial acetic acid. The novel halogenated carprofen derivatives were functionalized at the carboxylic group by esterification. The regioselectivity of the halogenation reaction was evidenced by NMR spectroscopy and confirmed by X-ray analysis. The compounds were screened for their in vitro antibacterial activity against planktonic cells and also for their anti-biofilm effect, using Gram-positive bacteria ( Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212) and Gram-negative bacteria ( Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853). The cytotoxic activity of the novel compounds was tested against HeLa cells. The pharmacokinetic and pharmacodynamic profiles of carprofen derivatives, as well as their toxicity, were established by in silico analyses.

An effective strategy to engineer selective photodynamic agents to surmount bacterial-infected diseases, especially Gram-positive bacteria remains a great challenge. Herein, we developed two examples of compounds for a proof-of-concept study where reactive differences in reactive oxygen species (ROS) can induce selective ablation of Gram-positive bacteria. Sulfur-replaced phenoxazinium (NBS-N) mainly generates a superoxide anion radical capable of selectively killing Gram-positive bacteria, while selenium-substituted phenoxazinium (NBSe-N) has a higher generation of singlet oxygen that can kill both Gram-positive and Gram-negative bacteria. This difference was further evidenced by bacterial fluorescence imaging and morphological changes. Moreover, NBS-N can also successfully heal the Gram-positive bacteria-infected wounds in mice. We believe that such reactive differences may pave a general way to design selective photodynamic agents for ablating Gram-positive bacteria-infected diseases., (© 2022 Wiley-VCH GmbH.)

Searching for adequate and effective compounds displaying antimicrobial activities, especially against Gram-positive bacteria, is an important research area due to the high hospitalization and mortality rates of these bacterial infections in both the human and veterinary fields. In this work, we explored ( E )-4-amino-3-((3,5-di- tert -butyl-2-hydroxybenzylidene)amino) benzoic acid (SB-1, harboring an intramolecular hydrogen bond) and ( E )-2-((4-nitrobenzilidene)amino)aniline (SB-2), two Schiff bases derivatives. Results demonstrated that SB-1 showed an antibacterial activity determined by the minimal inhibitory concentration (MIC) against Staphylococcus aureus , Enterococcus faecalis , and Bacillus cereus (Gram-positive bacteria involved in human and animal diseases such as skin infections, pneumonia, diarrheal syndrome, and urinary tract infections, among others), which was similar to that shown by the classical antibiotic chloramphenicol. By contrast, this compound showed no effect against Gram-negative bacteria ( Klebsiella pneumoniae , Escherichia coli , and Salmonella enterica ). Furthermore, we provide a comprehensive physicochemical and theoretical characterization of SB-1 (as well as several analyses for SB-2), including elemental analysis, ESMS, 1 H and 13 C NMR (assigned by 1D and 2D techniques), DEPT, UV-Vis, FTIR, and cyclic voltammetry. We also performed a computational study through the DFT theory level, including geometry optimization, TD-DFT, NBO, and global and local reactivity analyses.

Glycopeptides, a class of cell wall biosynthesis inhibitors, have been the antibiotics of choice against drug-resistant Gram-positive bacterial infections. Their unique mechanism of action involving binding to the substrate of cell wall biosynthesis and substantial longevity in clinics makes this class of antibiotics an attractive choice for drug repurposing and reprofiling. However, resistance to glycopeptides has been observed due to alterations in the substrate, cell wall thickening, or both. The emergence of glycopeptide resistance has resulted in the development of synthetic and semisynthetic glycopeptide analogues to target acquired resistance. Recent findings demonstrate that these derivatives, along with some of the FDA approved glycopeptides have been shown to have antimicrobial activity against Gram-negative bacteria, Mycobacteria, and viruses thus expanding their spectrum of activity across the microbial kingdom. Additional mechanisms of action and identification of novel targets have proven to be critical in broadening the spectrum of activity of glycopeptides. This review focuses on the applications of glycopeptides beyond their traditional target group of Gram-positive bacteria. This will aid in making the scientific community aware about the nontraditional activity profiles of glycopeptides, identify the existing loopholes, and further explore this antibiotic class as a potential broad-spectrum antimicrobial agent.

Background: Managing bacterial infections caused by multidrug-resistant (MDR) and biofilmforming bacteria is a global health concern. Therefore, enormous efforts were directed toward finding potential alternative antimicrobial agents, such as antimicrobial peptides (AMPs)., Aim: We aimed to synthesize a novel modified hybrid peptide designed from natural parents' peptides with enhanced activity and reduced toxicity profile., Methods: Rational design was used to hybridize the two antimicrobial peptides, in which the alpha-helical parts of BMAP-28 and LL-37 were combined. Then, several amino acid modifications were applied to generate a modified hybrid peptide named MAA-41. The physicochemical properties were checked using in silico methods. The MAA-41 was evaluated for its antimicrobial and anti-biofilm activities. Synergistic studies were performed with five conventional antibiotics. Finally, the cytotoxicity on mammalian cells and the hemolytic activity were assessed., Results: The MAA-41 revealed a broad-spectrum activity against Gram-positive and Gram-negative bacteria, including standard and MDR bacterial strains. The concentration against planktonic cells ranged between 10 and 20 μM, with higher potency against Gram-negative bacteria. The MAA-41 displayed potent activity in eradicating biofilm-forming cells, and the MBECs were equal to the MIC values reported for planktonic cells. This new peptide exhibited reduced toxicity profiles against erythrocyte cells but not against Vero cells. Combining MAA-41 peptides with conventional antibiotics improved the antimicrobial activity of the combined agents. Either synergistic or additive effects were shown as a significant decrease in MIC to 0.25 μM., Conclusion: This study proposes the validity of a novel peptide (MAA-41) with enhanced antimicrobial activity and reduced toxicity, especially when used as conventional antibiotic combinations., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Infections caused by Gram-positive bacteria, especially those able to invade and survive in host cells, threaten human health severely. It is therefore highly desirable to develop therapeutics that can selectively target and kill intracellular Gram-positive pathogens with minimal toxicity to host cells. Herein, it is described that the aggregation-induced emission luminogen (AIEgen) TPEPy-Et, containing a positively charged pyridinium group and a hydrophobic tetraphenylethylene fragment, is effective for Gram-positive bacteria detection and elimination. The fluorescence of TPEPy-Et is greatly enhanced after incubation with Gram-positive bacteria, which can be used to detect and trace the bacteria in cells. TPEPy-Et also shows excellent killing effects against both extracellular and intracellular Gram-positive bacteria through a membrane depolarization mechanism. The luminescent antibacterial agent TPEPy-Et is thus promising for diagnosis and therapy against intracellular bacterial infection., (© 2021 Wiley-VCH GmbH.)

Antimicrobial peptides (AMPs) are potential therapeutic agents against bacteria. We recently showed that a rationally designed AMP, termed Stripe, with an amphipathic distribution of native cationic and hydrophobic amino acids on its helical structure exhibited potent antimicrobial activity against Gram-positive and Gram-negative bacteria with negligible hemolytic activity and cytotoxicity. In this study, the structure-activity relationship of Stripe was elucidated by designing a series of antimicrobial peptides whereby amino acid residues of Stripe were exchanged with helix-destabilizing sarcosine residues. Stripe 1-5 peptides with hydrophobic amino acids substituted with sarcosine were predominantly unstructured and showed no antimicrobial activity, except against Escherichia coli (E. coli) (DH5α) cells. The activity against E. coli (DH5α) cells and the helicity of Stripe 1-5 peptides decreased concomitantly as the number of sarcosine residue substitutions increased. Stripe 1-5 peptides showed no hemolytic activity or cytotoxicity. The results indicate that sarcosine substitutions provide an approach to study the structure-activity relationship of helical AMPs, and the helicity of Stripe is an important feature defining its activity., (© 2021 European Peptide Society and John Wiley & Sons, Ltd.)

Advancements in antibiotic drug design are often hindered by missing information on how these small molecules interact with living cells. The antibiotic, daptomycin, has found clinical success and an emerging resistance, but a comprehensive picture of its mechanism of action has remained elusive. Using a surface-specific spectroscopy technique, second harmonic generation, we are able to quantitatively assess the binding of daptomycin to living cell membranes without the addition of exogenous labels. Our results reveal similar binding affinities for both Gram-positive and Gram-negative bacteria studied, including Escherichia coli . More importantly, we show that the presence of phosphate ions influences the binding of daptomycin to the Gram-positive bacterium Enterococcus faecalis . The role of environmental phosphate has not previously been considered in any proposed mechanism, and its implications are expected to be important in vivo .

Cell-cell communication is critical for bacterial survival in natural habitats, in which miscellaneous regulatory networks are encompassed. However, elucidating the interaction networks of a microbial community has been hindered by the population complexity. This study reveals that γ-butyrolactone (GBL) molecules from Streptomyces species, the major antibiotic producers, can directly bind to the acyl-homoserine lactone (AHL) receptor of Chromobacterium violaceum and influence violacein production controlled by the quorum sensing (QS) system. Subsequently, the widespread responses of more Gram-negative bacterial AHL receptors to Gram-positive Streptomyces signaling molecules are unveiled. Based on the cross-talk between GBL and AHL signaling systems, combinatorial regulatory circuits (CRC) are designed and proved to be workable in Escherichia coli (E. coli). It is significant that the QS systems of Gram-positive and Gram-negative bacteria can be bridged via native Streptomyces signaling molecules. These findings pave a new path for unlocking the comprehensive cell-cell communications in microbial communities and facilitate the exploitation of innovative regulatory elements for synthetic biology., (© 2021. Science China Press and Springer-Verlag GmbH Germany, part of Springer Nature.)

Bacteria are primary agents of organic substrate metabolisation and elemental cycling in landfills. Two major bacterial groups, namely, Gram-positive (GP) and Gram-negative (GN), drive independent metabolic functions that contribute to waste stabilisation. There is a lack of explicit exploration of how these different bacterial guilds respond to changing carbon (C) availability and substrate depletion as landfills age and how landfill geochemistry regulates their distribution. This study investigated and compared the abundance and vertical distribution of GP and GN bacteria in 14- and 36-year-old municipal landfills and explored linkages among bacterial groups, nutrient elements, heavy metals and soil texture. We found higher GP bacteria in the 14-year-old landfill, while GN bacteria dominated the 36-year-old landfill. The non-metric multidimensional scaling (nMDS) analysis showed that dissimilarities in the relative abundance of the GP and GN bacteria were linked distinctly to landfill age, and not depth. In support of this inference, we further found that GP and GN bacteria were negatively correlated with heavy metals and essential nutrients in the 14- and 36-year-old landfills, respectively. Notably, the GP/GN ratio, an indicator of relative C available for bacterial mineralisation, was greater in the14-year-old landfill, suggesting greater C availability. Conversely, the C to N ratio was higher in the 36-year-old landfill, indicating lower N mineralisation. Collectively, the results of the study reveal key insights into how landfill ageing and stabilisation influence distinct functional shifts in the abundance of GP and GN bacteria, and these are mainly driven by changes in C and N bioavailability., (© 2021. The Author(s), under exclusive licence to Springer Nature Switzerland AG part of Springer Nature.)

Objective: Although many bacterial culture media are available commercially, there is a continuous effort to develop better selective media for bacteria, which cannot be grown on existing media. While exploring antibacterial properties of clove, we observed that it has the potential to selectively inhibit growth of certain types of bacteria. This led us to do the experiments, which resulted in developing a new media which selectively allowed the growth of only Gram-negative bacteria, while inhibiting the Gram-positive bacteria., Results: Mueller Hinton Agar (MHA) was used as the base media and was modified to develop MHA-C15 (MHA containing 15% volume/volume water extract of clove). Gram-negative bacterial pathogens Escherichia coli, Klebsiella pneumoniae, Salmonella typhimurium and Pseudomonas aeruginosa grew on MHA-C15. However, none of the major Gram-positive bacterial pathogens such as Staphylococcus aureus, Streptococcus pneumoniae, Streptococcus pyogenes, Streptococcus mutans, Bacillus spp. and Enterococcus spp. grew on it. Taken together, these findings show that MHA-C15 is a newly developed selective media for culture of Gram-negative bacteria.

Pathogenic infections, particularly caused by Gram-positive bacteria (G + ), pose a serious threat to human health, and therefore the fast and accurate discrimination of G + bacteria from Gram-negative bacteria (G - ) and fungi is highly desirable. Organic molecules with facile synthesis, robust photostability, good biocompatibility, and high selectivity toward pathogens are urgently needed in the clinical diagnosis and therapy. To this end, herein we report the synthesis of two naphthalimide-based bioprobes named tetraphenylethylene-naphthalimide (TPE-NIM) and triphenylamine-naphthalimide (TPA-NIM) with aggregation-induced emission (AIE) characteristic. First, the staining capacity of the designed AIEgens toward six kinds of bacteria and two kinds of fungi was evaluated. Both TPE-NIM and TPA-NIM showed a high degree of binding/imaging selectivity for G + bacteria over G - bacteria and fungi via a wash-free protocol. Second, the two AIEgens had the ability to visualize the biofilms formed by G + bacteria (Staphylococcus aureus) and can quickly track the G + bacteria (Staphylococcus aureus) in red blood cell suspensions. Third, we have revealed that electrostatic attraction and hydrophobic interaction both contribute to the selective binding of the AIEgens toward G + bacteria. In view of the high binding/imaging specificity toward G + bacteria, low hemolysis rates, and low toxicity toward the bacterial cells, these AIEgens can be applied for the clinical detection of pathogenic infections caused by G + bacteria and broaden the theranostic applications of AIE materials., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

N-aryl-oxazolidinones is a prominent family of antimicrobials used for treating infections caused by clinically prevalent Gram-positive bacteria. Recently, boron-containing compounds have displayed intriguing potential in the antibiotic discovery setting. Herein, we report the unprecedented introduction of a boron-containing moiety such as an aryl boronic acid in the external region of the oxazolidinone structure via a chemoselective acyl coupling reaction. As a result, we accessed a series of analogues with a distal aryl boronic pharmacophore on the oxazolidinone scaffold. We identified that a peripheric linear conformation coupled with freedom of rotation and no further substitution on the external aryl boronic ring, an amido linkage with hydrogen bonding character, in addition to a para-relative disposition between boronic group and linker, are the optimal combination of structural features in this series for antimicrobial activity. In comparison to linezolid, the analogue comprising all those features, compound 20b, displayed levels of antimicrobial activity augmented by an eight-fold to a thirty-two-fold against a panel of Gram-positive strains, and a near one hundred-fold against Escherichia coli JW5503, a Gram-negative mutant strain with a defective efflux capability., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

The release of extracellular vesicles (EVs) is a process conserved across the three domains of life. Amongst prokaryotes, EVs produced by Gram-negative bacteria, termed outer membrane vesicles (OMVs), were identified more than 50 years ago and a wealth of literature exists regarding their biogenesis, composition and functions. OMVs have been implicated in benefiting numerous metabolic functions of their parent bacterium. Additionally, OMVs produced by pathogenic bacteria have been reported to contribute to pathology within the disease setting. By contrast, the release of EVs from Gram-positive bacteria, known as membrane vesicles (MVs), has only been widely accepted within the last decade. As such, there is a significant disproportion in knowledge regarding MVs compared to OMVs. Here we provide an overview of the literature regarding bacterial membrane vesicles (BMVs) produced by pathogenic and commensal bacteria. We highlight the mechanisms of BMV biogenesis and their roles in assisting bacterial survival, in addition to discussing their functions in promoting disease pathologies and their potential use as novel therapeutic strategies.

Protonectin was a typical amphiphilic antimicrobial peptide with potent antimicrobial activity against Gram-positive and Gram-negative bacteria. In the present study, when its eleventh amino acid in the sequence was substituted by phenylalanine, the analog named phe-Prt showed potent antimicrobial activity against Gram-positive bacteria, but no antimicrobial activity against Gram-negative bacteria, indicating a significant selectivity between Gram-positive bacteria and Gram-negative bacteria. However, when Gram-negative bacteria were incubated with EDTA, the bacteria were susceptible to phe-Prt. Next, the binding effect of phe-Prt with LPS was determined. Our result showed that LPS could hamper the bactericidal activity of phe-Prt against Gram-positive bacteria. The result of zeta potential assay further confirmed the binding effect of phe-Prt with LPS for it could neutralize the surface charge of E. coli and LPS. Then, the effect of phe-Prt on the integrity of outer membrane of Gram-negative bacteria was determined. Our results showed that phe-Prt had a much weaker disturbance to the outer membrane of Gram-negative bacteria than the parent peptide protonectin. In summary, the introduction of L-phenylalanine into the sequence of antimicrobial peptide protonectin made phe-Prt show significant selectivity against Gram-positive bacteria, which could partly be attributed to the delay effect of LPS for phe-Prt to access to cell membrane. Although further study is still needed to clarify the exact mechanism of selectivity, the present study provided a strategy to develop antimicrobial peptides with selectivity toward Gram-positive and Gram-negative bacteria.

The transition between cell envelopes with one membrane (Gram-positive or monoderm) and those with two membranes (Gram-negative or diderm) is a fundamental open question in the evolution of Bacteria. Evidence of the presence of two independent diderm lineages, the Halanaerobiales and the Negativicutes, within the classically monoderm Firmicutes has blurred the monoderm/diderm divide and specifically anticipated that other members with an outer membrane (OM) might exist in this phylum. Here, by screening 1,639 genomes of uncultured Firmicutes for signatures of an OM, we highlight a third and deep branching diderm clade, the Limnochordia, strengthening the hypothesis of a diderm ancestor and the occurrence of independent transitions leading to the monoderm phenotype. Phyletic patterns of over 176,000 protein families constituting the Firmicutes pan-proteome identify those that strongly correlate with the diderm phenotype and suggest the existence of new potential players in OM biogenesis. In contrast, we find practically no largely conserved core of monoderms, a fact possibly linked to different ways of adapting to repeated OM losses. Phylogenetic analysis of a concatenation of main OM components totalling nearly 2,000 amino acid positions illustrates the common origin and vertical evolution of most diderm bacterial envelopes. Finally, mapping the presence/absence of OM markers onto the tree of Bacteria shows the overwhelming presence of diderm phyla and the non-monophyly of monoderm ones, pointing to an early origin of two-membraned cells and the derived nature of the Gram-positive envelope following multiple OM losses.

Background: Gram-negative bacilli (GNB), notably Acinetobacter spp., Pseudomonas spp., and Klebsiella spp., are becoming increasingly resistant to carbapenems and are associated with high health care costs and mortality, becoming a global concern., Objective: To determine the prevalence rates of carbapenem resistance among Acinetobacter spp., Pseudomonas spp., and Klebsiella spp. in the main sites of nosocomial infection at a tertiary care hospital in southern Brazil and the consequent therapeutic implications., Methods: Cultures processed at the institution's laboratory in 2017 were analyzed, and those positive for Acinetobacter spp., Pseudomonas spp., and Klebsiella spp. were identified. Antibiograms were evaluated for meropenem sensitivity following the Clinical Laboratory Standards Institute guidelines., Results: Acinetobacter spp. had the lowest prevalence among the three GNB, and resistance of this pathogen to meropenem at different sites of infection ranged from 36% (blood) to 82% (respiratory tract). Pseudomonas spp. was highly prevalent at the respiratory tract (31%) and had a high resistance rate to meropenem in rectal swab samples (71%), but a relatively low frequency at infection sites (skin/soft tissue, 13%; blood, 25%). Klebsiella spp. was identified in 7.5% of the blood cultures and 15% of the urine cultures and was the chief colonizer among all pathogens, representing 54% of all rectal swab samples, of which 53% were meropenem resistant. At sites of infection, rates of Klebsiella spp. resistant to meropenem ranged from 19% (skin) to 55% (vascular catheter)., Conclusions: The prevalence of carbapenem-resistant GNB at our hospital was relatively low compared to national and international data; thus, meropenem remains a good therapeutic option against these bacteria. Other antibiotics effective against GNB, such as ceftazidime, cefepime, and piperacillin-tazobactam, can be used in most cases, while meropenem should be reserved for patients with sepsis. Strict contact precaution measures are still needed, given the high resistance rate observed at the colonizing site., (Copyright © 2020 Sociedade Brasileira de Infectologia. Published by Elsevier España, S.L.U. All rights reserved.)

Antimicrobial peptides (AMPs) are produced by all forms of life, ranging from eukaryotes to prokaryotes, and they are a crucial component of innate immunity, involved in clearing infection by inhibiting pathogen colonization. In the recent past, AMPs received high attention due to the increase of extensive antibiotic resistance by these pathogens. AMPs exhibit a diverse spectrum of activity against bacteria, fungi, parasites, and various types of cancer. AMPs are active against various bacterial pathogens that cause disease in animals and plants. However, because of the coevolution of host and pathogen interaction, bacteria have developed the mechanisms to sense and exhibit an adaptive response against AMPs. These resistance mechanisms are playing an important role in bacterial virulence within the host. Here, we have discussed the different resistance mechanisms used by gram-positive and gram-negative bacteria to sense and combat AMP actions. Understanding the mechanism of AMP resistance may provide directions toward the development of novel therapeutic strategies to control multidrug-resistant pathogens.

Previously, we described the design and synthesis of three nine-residue AMPs, P9Nal(SS), P9Trp(SS), and P9Nal(SR), showing high stability in serum and broad spectrum antimicrobial activity. The peptides P9Trp(SS) and P9Nal(SR) differ from P9Nal(SS) for the replacement of the two 2Nal residues with Trp residues and for the replacement of the two Cys (StBu) with Cys (tBu) residues, respectively. These changes led to peptides with a lower hydrophobicity respect to the P9Nal(SS). Interestingly, the three peptides have very similar activity against Gram-negative bacteria. Instead, they exhibit a significant difference towards Gram-positive bacteria, being P9Nal(SS) the most active. In order to evaluate the impact of amino acids substitution on membranotropic activity and rationalize the observed effects in vivo, here, we report the detailed biophysical characterization of the interaction between P9Nal(SR) and P9Trp(SS) and liposomes by combining differential scanning calorimetry, circular dichroism, and fluorescence spectroscopy. The comparison with the results for the previously characterized P9Nal(SS) peptide reveals similarities and differences on the interaction process and perturbation activities. It was found that the three peptides can penetrate at different extent inside the bilayer upon changing their conformation and inducing lipid domains formation, revealing that the formation of lipid domains is fundamental for the activity against Gram-negative bacteria. On the contrary, the dissimilar activity against Gram-positive bacteria well correlate with the different affinity of peptides for the lipoteichoic acid, a component selectively present in the cell wall of Gram-positive bacteria., (© 2020 European Peptide Society and John Wiley & Sons, Ltd.)

To date, many proteins generated by large-scale genome sequencing projects are still uncharacterized and subject to intensive investigations by both experimental and computational means. Knowledge of protein subcellular localization (SCL) is of key importance for protein function elucidation. However, it remains a challenging task, especially for multiple sites proteins known to shuttle between cell compartments to perform their proper biological functions and proteins which do not have significant homology to proteins of known subcellular locations. Due to their low-cost and reasonable accuracy, machine learning-based methods have gained much attention in this context with the availability of a plethora of biological databases and annotated proteins for analysis and benchmarking. Various predictive models have been proposed to tackle the SCL problem, using different protein sequence features pertaining to the subcellular localization, however, the overwhelming majority of them focuses on single localization and cover very limited cellular locations. The prediction was basically established on sorting signals, amino acids compositions, and homology. To improve the prediction quality, focus is actually on knowledge information extracted from annotation databases, such as protein-protein interactions and Gene Ontology (GO) functional domains annotation which has been recently a widely adopted and essential information for learning systems. To deal with such problem, in the present study, we considered SCL prediction task as a multi-label learning problem and tried to label both single site and multiple sites unannotated bacterial protein sequences by mining proteins homology relationships using both GO terms of protein homologs and PSI-BLAST profiles. The experiments using 5-fold cross-validation tests on the benchmark datasets showed a significant improvement on the results obtained by the proposed consensus multi-label prediction model which discriminates six compartments for Gram-negative and five compartments for Gram-positive bacterial proteins., (© 2020 Hafida Bouziane and Abdallah Chouarfia, Published DeGruyter, Berlin/Boston.)

Background: Interaction of C. albicans with oral bacteria is crucial for its persistence, but also plays a potential role in the infection process. In the oral cavity, it grows as part of dental plaque biofilms. Even though growth and interaction of C. albicans with certain bacterial species has been studied, little is known about its biofilm growth in vitro in the simultaneous presence of Gram-negative and Gram-positive bacteria. The aim was to evaluate the growth of C. albicans in polymicrobial biofilms comprising oral Gram-negative and Gram-positive bacteria. Further, we also aimed to assess the potential of C. albicans in the Candida-bacteria polymicrobial biofilm to elicit cytokine gene expression and cytokine production from human blood cells., Results: C. albicans cell counts increased significantly up to 48 h in polymicrobial biofilms (p < 0.05), while the bacterial counts in the same biofilms increased only marginally as revealed by qPCR absolute quantification. However, the presence of bacteria in the biofilm did not seem to affect the growth of C. albicans. Expression of IL-8 gene was significantly (p < 0.05) higher upon stimulation from biofilm-supernatants than from biofilms in polymicrobial setting. On the contrary, TNF-α expression was significantly higher in biofilms than in supernatants but was very low (1-4 folds) in the monospecies biofilm of C. albicans. ELISA cytokine quantification data was in agreement with mRNA expression results., Conclusion: Persistence and enhanced growth of C. albicans in polymicrobial biofilms may imply that previously reported antagonistic effect of A. actinomycetemcomitans was negated. Increased cytokine gene expression and cytokine production induced by Candida-bacteria polymicrobial biofilms and biofilm supernatants suggest that together they possibly exert an enhanced stimulatory effect on IL-8 and TNF-α production from the host.

Osteomyelitis of the foot and ankle is a challenge to treat and creates a significant demand on both the patient and the healthcare system. The purposes of this study were to determine the microorganisms associated with foot and ankle osteomyelitis, to evaluate the change in methicillin-resistant Staphylococcus aureus (MRSA) between 2005 and 2010, and to determine the relationship between these infecting organisms and patient comorbidities. The medical records for 302 patients diagnosed with osteomyelitis of the foot and ankle, 151 in 2005 and 151 in 2010, were randomly selected and evaluated. The authors reviewed the demographics, comorbidities, microorganism(s) confirmed with bone biopsy and culture, location, and use of antibiotics before bone biopsy. Gram-positive bacteria were the most prevalent, composing 81.9% of the isolates in 2005 and 59.6% in 2010. Methicillin-sensitive Staphylococcus aureus was the most common in both cohorts. Conversely, the incidence of MRSA statistically decreased from 28.3% to 10.6% from 2005 to 2010 (p < .0001). Gram-negative bacteria were found in 39.5% of the 2005 isolates and 31.8% of those from 2010. Pseudomonas sp. was the most common gram-negative bacteria. Patients with peripheral vascular disease had a significantly higher incidence of gram-negative bacteria (odds ratio 2.1, 95% confidence interval, 1.3 to 3.6, p = .003). The results of this study reveal that MSSA was the most common bacteria, incidence of MRSA decreased between the 2005 to 2010, and patients with peripheral vascular disease have a significantly higher incidence of gram-negative bacteria., (Copyright © 2019 the American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.)

Objective: Clinical diagnostics often requires the detection of multiple bacterial species in limited clinical samples with a single DNA extraction method. This study aimed to compare the bacterial DNA extraction efficiency of two lysis methods automated with the MagNA-Pure LC instrument. The samples included five oral bacterial species (three Gram-positive and two Gram-negative) with or without human saliva background., Methods: Genomic DNA (gDNA) was extracted from bacterial cultures by bead-beating lysis (BMP) or chemical lysis (MP), followed by automated purification and measurement by quantitative PCR., Results: For pure bacterial cultures, the MP method yielded higher quantities of extracted DNA and a lower detection limit than the BMP method, except where the samples contained high numbers of Gram-positive bacteria. For bacterial cultures with a saliva background, no difference in gDNA extraction efficacy was observed between the two methods., Conclusions: The efficiency of a bacterial DNA extraction method is not only affected by the bacterial cell wall structure but also by the sample milieu. The MP method provided superior gDNA extraction efficiency when the samples contained a single bacterial species, whereas either of the BMP and MP methods could be applied with similar efficiencies to samples containing multiple species of bacteria.

Background: Myrtus communis is a typical plant of Mediterranean area. The different parts of this plant such as berries, branches, and leaves have been used worldwide as a traditional/folk medicine for the treatment of various ailments and diseases., Methods: Ethanolic leaf extract of the plant was prepared by Soxhlet extraction method. Zone of inhibition, minimum inhibitory concentration and minimal bactericidal concentration were determined by well diffusion method and microplate alamar blue assay. GC-MS analysis was carried out to identify the compounds present in the extract. Microscopy and ImageJ software were used respectively for morphology and cell-length measurements. GraphPad Prism was used for statistical analysis., Results: The ethanolic extract showed strong inhibitory effect against Gram-positive and acid-fast bacteria with significant inhibition-zone size (9-25 mm), MIC (4.87-78 μg/ml), as well as MBC (0.3-20 mg/ml). However, no effect was observed on the growth of Gram-negative bacteria. The growth inhibition was found to be associated with the damage of cell wall as the extract-treated cells were sensitive to cell wall-targeting antibiotics and displayed the cell wall damage-depicting morphological defects. GC-MS analysis confirmed the presence of novel compounds in addition to the most representative compounds of the essential oils/extracts of M. communis of other country origins., Conclusion: These results demonstrate that M. communis leaf extract could be the source of compounds to be used for the treatment of Gram-positive bacterial infections. This is the first report, which provides insights into the mechanism of action of the extract in inhibiting the growth of Gram-positive bacteria.

To address the global challenge of emerging antimicrobial resistance, the hitherto most successful strategy to new antibiotics has been the optimization of validated natural products; most of these efforts rely on semisynthesis. Herein, we report the semisynthetic modification of amidochelocardin, an atypical tetracycline obtained via genetic engineering of the chelocardin producer strain. We report modifications at C4, C7, C10 and C11 by the application of methylation, acylation, electrophilic substitution, and oxidative C-C coupling reactions. The antibacterial activity of the reaction products was tested against a panel of Gram-positive and Gram-negative pathogens. The emerging structure-activity relationships (SARs) revealed that positions C7 and C10 are favorable anchor points for the semisynthesis of optimized derivatives. The observed SAR was different from that known for tetracyclines, which underlines the pronounced differences between the two compound classes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019 Elsevier Masson SAS. All rights reserved.)

Background: The incidences of opportunistic bacterial infections have increased in the past two decades or is expected to increase in the near future. Despite the availability of various classes of antibiotics, bacterial infections are not handled properly., Methods: Thus, in the present study, we have repurposed atorvastatin against various types of bacterial strains by using in silico, in vitro, and in vivo studies. Furthermore, a preliminary safety study was conducted using MTT assay., Results: In silico study results have revealed that atorvastatin has good interaction with various targets of bacterial cell like that of the reference ligand. However, under in vitro conditions,it was found that atorvastatin was effective at higher concentrations (>128 μg/ml) against various bacterial strains. Thus, further, atorvastatin was tested in combination with standard antibiotics and has shown a synergistic effect., Conclusion: The MTT assay results have revealed non-cytotoxic activity of atorvastatin. In conclusion, atorvastatin in combination with standard drugs could be developed as an antibacterial agent., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Maternal bacterial sepsis during pregnancy and the postpartum period is a common cause of maternal mortality and fetal morbidity and mortality. This study was performed to analyze perinatal prognosis and related factors of maternal bacterial sepsis in west China.We conducted a cross-sectional study of pregnant women with bacterial sepsis who were admitted into a tertiary care center in western China between 2011and 2015. Data from these cases were collected and analyzed.Eighty six women were identified with bacterial sepsis in our hospital, and the incidence of maternal bacterial sepsis was 1.7 per 1000 maternities, the incidence of septic shock was 1.8 per 10,000 maternities, and 1 maternal death occurred. Among the 86 pregnant women with bacterial sepsis, genital tract infection was the most common source of infection (41/86, 47.7%). The most common bacteria in the Gram-positive bacteria group was Listeria monocytogenes and in the Gram-negative bacteria group was Escherichia coli. The premature delivery rate (65.7%) was substantially higher in the Gram-negative bacteria group (P = .011), and the miscarriage rate (31.3%) was higher in the Gram-positive bacteria group (P = .042). The fetal/neonatal mortality rate was 20% (21/105) and higher in the Gram-positive bacteria group (P = .008), and the infant mortality rate in 1 year was 7.1% (6/84).Bacterial sepsis remains an alarming cause of both maternal and fetal morbidity and mortality, and infant mortality. Key treatment involves a multi-disciplinary group of clinicians with experience in all aspects of the care of pregnant women with sepsis and early initiation of appropriate antibiotics according to the type of bacterial infection. The effect of maternal sepsis on long-term fetal outcome should be investigated.

The objective of this study was to determine the in vitro antimicrobial activity of several organic acids and their derivatives against Gram-positive (G+) and Gram-negative (G-) bacteria. Butyric acid, valeric acid, monopropionin, monobutyrin, monovalerin, monolaurin, sodium formate, and ProPhorce-a mixture of sodium formate and formic acid (40:60 w / v )-were tested at 8 to 16 concentrations from 10 to 50,000 mg/L. The tested bacteria included G- bacteria ( Escherichia coli, Salmonella enterica Typhimurium, and Campylobacter jejuni ) and G+ bacteria ( Enterococcus faecalis, Clostridium perfringens, Streptococcus pneumoniae , and Streptococcus suis ). Antimicrobial activity was expressed as minimum inhibitory concentration (MIC) of tested compounds that prevented growth of tested bacteria in treated culture broth. The MICs of butyric acid, valeric acid, and ProPhorce varied among bacterial strains with the lowest MIC of 500-1000 mg/L on two strains of Campylobacter . Sodium formate at highest tested concentrations (20,000 mg/L) did not inhibit the growth of Escherichia coli , Salmonella Typhimurium, and Enterococcus faecalis , but sodium formate inhibited the growth of other tested bacteria with MIC values from 2000 to 18,800 mg/L. The MIC values of monovalerin, monolaurin, and monobutyrin ranged from 2500 to 15,000 mg/L in the majority of bacterial strains. Monopropionin did not inhibit the growth of all tested bacteria, with the exception that the MIC of monopropionin was 11,300 mg/L on Clostridia perfringens . Monolaurin strongly inhibited G+ bacteria, with the MIC value of 10 mg/L against Streptococcus pneumoniae . The MIC tests indicated that organic acids and their derivatives exhibit promising antimicrobial effects in vitro against G- and G+ bacteria that are resistant to antimicrobial drugs. The acid forms had stronger in vitro antimicrobial activities than ester forms, except that the medium chain fatty acid ester monolaurin exhibited strong inhibitory effects on G+ bacteria.

Treatment of critically ill patients entails a great risk for intrahospital infections. Systematic monitoring of intrahospital infection data is a widely used practice in developed countries, while in developing and underdeveloped countries these data are scarce. In Bosnia and Herzegovina, a developing country, precise data cannot be found; hence, this study was created with the aim to monitor the profile and resistance patterns of microorganisms isolated from patients being treated in the only medical intensive care unit (MICU) in the country. This is a retrospective observational study of microorganisms isolated from all patients treated at MICU in the University Clinical Center of Republic of Srpska from January 1 through December 31, 2017. Analysis of all samples was performed using standardized microbiological procedures, while sensitivity to antimicrobials was performed using the disk diffusion method. One thousand six hundred twenty-five samples were taken from 633 critically ill patients and sent off for analysis; 572 were positive for bacteria (35.2%). Gram-negative bacteria were isolated more frequently (65.2%), specifically Acinetobacter baumannii (25.5%), followed by Klebsiella spp. (10.8%). A. baumannii was resistant to all antibiotics except for colistin, to which it was highly sensitive (99.7%). It was moderately sensitive (76%) to rifampicin. Staphylococcus epidermidis , Staphylococcus aureus, and Enterococci were the most prevalent Gram-positive bacteria (15%, 7.3%, and 9.2%, respectively) isolated in this study. It is clear from this study that Gram-negative bacteria are predominant in the newly established MICU. A. baumannii was found to be the most prevalent Gram-negative bacteria, and S. epidermidis was the most prevalent Gram-positive bacteria.

Objective: To describe and compare the clinical presentation, management, and outcomes of cardiovascular implantable electronic device (CIED) infections due to gram-negative bacteria (GNB) and CIED infections due to gram-positive bacteria (GPB)., Patients and Methods: We retrospectively reviewed all CIED infection cases at Mayo Clinic from January 1, 1992, through December 31, 2015. Cases were classified based on positive microbiology data from extracted devices or blood cultures., Results: Of the 623 CIED infections during the study period, 31 (5.0%) were caused by GNB and 323 (51.8%) by GPB. Patients in the GNB group were more likely to present with local inflammatory findings at the pocket site (90.3% vs 72.4%; P=.03). All patients with bacteremia due to GNB had concomitant pocket infection compared with those with GPB (100% vs 33.9%; P=.002). After extraction, 41.9% of patients in the GNB group were managed with oral antibiotics vs 2.4% in the GPB group (P<.001). There were no statistically significant differences in infection relapse/recurrence or 1-year survival rates between the 2 groups., Conclusion: Compared with CIED infections caused by GPB, those due to GNB are more likely to present with pocket infection. Device-related GNB bacteremia almost always originates from the generator pocket. After extraction, oral antibiotic drug therapy may be a reasonable option in select cases of pocket infections due to GNB. No difference in outcomes was observed between the 2 groups., (Copyright © 2018 Mayo Foundation for Medical Education and Research. Published by Elsevier Inc. All rights reserved.)

The oral mucosa is a first line of defense against pathogenic organisms and yet tolerates food antigens and resident bacteria. Mucosal epithelial cells are emerging as important regulators of innate and adaptive immune responses. However, the contribution of oral epithelial cells (OECs) determining oral immunity is understudied. Here, we evaluated the ability of H413 and TR146 cells, two OEC lines derived from human oral squamous cell carcinomas, and primary OECs to modulate immune responses to a cocktail of Gram + and Gram - bacteria known as MV130. OECs expressed CD40 constitutively and class II major histocompatibility complex (MHC II) molecules when stimulated with IFNγ, but not CD80 or CD86. Dendritic cells (DCs) treated with bacteria in co-culture with OECs did not fully mature, as judged by the expression of MHC II, CD80 and CD86, and barely released IL-12 and TNFα, compared to control DCs. Furthermore, in the presence of OECs, DCs were unable to stimulate allogenic naive CD4 T cells to produce IFNγ and TNFα. Similarly, OECs in culture with total CD4 T cells or Th1 cells stimulated with anti-CD3 and anti-CD28 antibodies abrogated CD25 and CD69 expression, T cell proliferation and the release of IFNγ and TNFα. The inhibition on T cell activation by OECs was cell-contact dependent, TGFβ independent and largely irreversible. Overall, this behavior of OECs is likely key to avoid immune system over-reaction against resident bacteria.

There is a wide range of factors affecting bacterial adhesion and biofilm formation. However, in both food processing and medical settings, it is very hard to obtain suitably controlled conditions so that the factors that reduce surface colonisation and biofouling can be studied. The aim of this study was to evaluate the effect of glucose concentration, temperature and stainless steel (SS) surface roughness on biofouling by four common pathogens ( Escherichia coli , Staphylococcus aureus , Pseudomonas aeruginosa and L. monocytogenes ). Among the tested variables, the untreated SS surface (3C) was shown to be fouled more than 3D polished, brushed or electropolished SS surfaces. Although an array of parameters influenced biofouling, the most promising control measure was the influence of low temperature (4 °C) that reduced biofouling even in the case of the psychrophilic Listeria monocytogenes . The study findings could significantly contribute to the prevention of SS surface contamination and consequential biofouling by food and healthcare associated pathogens.

The Clinical and Laboratory Standards Institute (CLSI) broth microdilution method was used to evaluate the in vitro activities of plazomicin and comparator antimicrobial agents against 7,712 Gram-negative and 4,481 Gram-positive bacterial pathogens obtained from 2013 to 2017 from patients in Canadian hospitals as part of the CANWARD Surveillance Study. Plazomicin demonstrated potent in vitro activity against Enterobacteriaceae (MIC 90 ≤ 1 µg/ml for all species tested except Proteus mirabilis and Morganella morganii ), including aminoglycoside-nonsusceptible, extended-spectrum β-lactamase (ESBL)-positive, and multidrug-resistant (MDR) isolates. Plazomicin was equally active against methicillin-susceptible and methicillin-resistant isolates of Staphylococcus aureus ., (Copyright © 2018 American Society for Microbiology.)

Objective: To summarize the bioactive substances contained in bacterial extracellular vesicles (EVs) and their mechanisms in mediating bacterial-bacterial and bacterial-host interactions, as well as their mechanisms for use in implant infection-associated clinical guidance., Methods: A wide range of publications on bacterial-derived EVs were extensively reviewed, analyzed, and summarized., Results: Both gram-negative bacteria (G - bacteria) and gram-positive bacteria (G + bacteria) can secrete EVs which contain a variety of bioactive substances, including proteins, lipids, nucleic acids, and virulence factors, and mediate bacterial-bacterial and bacterial-host interactions. EVs play an important role in the pathogenic mechanism of bacteria., Conclusion: Bioactive substances contained within bacteria-derived EVs play an important role in the pathogenesis of bacterial infectious diseases. In-depth study and understanding of their pathogenic mechanisms can provide new insights which will improve early clinical diagnosis, prevention, and treatment of implant-associated infection. However, at present, research in this area is still in its infancy, and many more in-depth mechanisms need to be further studied.

Background: Antimicrobial activity of tigecycline and comparator agents was assessed in vitro against 27857 isolates source from blood samples collected between 2012 and 2016 as part of the Tigecycline Evaluation and Surveillance Trial (TEST)., Methods: The broth microdilution methods was used to determine  minimum inhibitory concentrations (MIC) of blood-borne isolates according to guildlines of the Clinical and Laboratory Standards Institute (CLSI). Antimicrobial susceptibility breakpoints from CLSI guidelines were used as standards to determine susceptibility against comparator agents, whereas tigecycline breakpoints were provided by the US Food and Drug Administration (FDA)., Results: More than 91% Enterobacteriaceae isolates, belonging to Escherichia coli , Klebsiella pneumoniae , Enterobacter cloacae and Serratia marcescens , were susceptible to amikacin, meropenem, and tigecycline. Meropenem resistance was observed in 8% of K.pneumoniae isolates worldwide. Extended-spectrum β-lactamase (ESBL) was produced in 15.9 and 20.9% E.coli and  K.pneumoniae isolates, respectively. MIC 90 of tigecycline against Acinetobacter baumannii was 2 μg/ml.  The highest proportion of susceptible A.baumannii isolates was 70.8% for minocycline. Among  P.aeruginose  isolates worldwide, 71.1-94.9% were susceptible to six antibiotics. Almost all Staphylococcus aureus isolates were susceptible to linezolid(100%), vancomycin(100%), and tigecycline (99.9%). The proportion of methicillin-resistant S.aureus (MRSA) was 33.0% among S.aureus isolates worldwide; it was highest in Asia with 46.6%, followed by North America and Latin America with 37.7 and 34.2%, respectively. Vancomycin-resistant (VR) isolates represented 1.4% of Enterococcus faecalis (VR. E.faecalis ) and 27.6% of  Enterococcus faecium (VR. E.faecium ). Highest percentages of VR. E.faecium were found in North America and Latin America, with 61.6 and 58.1% of the isolates, respectively. Production of penicillin-resistant  Streptococcus pneumoniae (PRSP) represented 9.0% of S. pneumoniae isolates worldwide; the PRSP proportion was 25.8% in Asia, 13.0% in Africa, and 11.8% in Latin America., Conclusions: In our study, tigecycline was the only antibiotic that was active against over 90% of all major blood-borne pathogens. A global comparison revealed that antimicrobial resistance was higher in Africa, Asia and Latin America than in Europe and North America., Competing Interests: Not applicable.Not applicable.ZZ, MC and YL declare no competing interests. YY and PS are employees of Pfizer, Inc.Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

The safe use and design of nanoparticles (NPs) ask for a comprehensive interpretation of their potentially adverse effects on (micro)organisms. In this respect, the prior assessment of the interactions experienced by NPs in the vicinity of - and in contact with - complex biological surfaces is mandatory. It requires the development of suitable techniques for deciphering the processes that govern nano-bio interactions when a single organism is exposed to an extremely low dose of NPs. Here, we used atomic force spectroscopy (AFM)-based force measurements to investigate at the nanoscale the interactions between carboxylate-terminated polyamidoamine (PAMAM) nanodendrimers (radius ca. 4.5 nm) and two bacteria with very distinct surface properties, Escherichia coli and Lactococcus lactis. The zwitterionic nanodendrimers exhibit a negative peripheral surface charge and/or a positive intraparticulate core depending on the solution pH and salt concentration. Following an original strategy according to which a single dendrimer NP is grafted at the very apex of the AFM tip, the density and localization of NP binding sites are probed at the surface of E. coli and L. lactis mutants expressing different cell surface structures (presence/absence of the O-antigen of the lipopolysaccharides (LPS) or of a polysaccharide pellicle). In line with electrokinetic analysis, AFM force measurements evidence that adhesion of NPs onto pellicle-decorated L. lactis is governed by their underlying electrostatic interactions as controlled by the pH-dependent charge of the peripheral and internal NP components, and the negatively-charged cell surface. In contrast, the presence of the O-antigen on E. coli systematically suppresses the adhesion of nanodendrimers onto cells, may the apparent NP surface charge be determined by the peripheral carboxylate groups or by the internal amine functions. Altogether, this work highlights the differentiated roles played by surface polysaccharides in mediating NP attachment to Gram-positive and Gram-negative bacteria. It further demonstrates that the assessment of NP bioadhesion features requires a critical analysis of the electrostatic contributions stemming from the various structures composing the stratified cell envelope, and those originating from the bulk and surface NP components. The joint use of electrokinetics and AFM provides a valuable option for rapidly addressing the binding propensity of NPs to microorganisms, as urgently needed in NP risk assessments.