Bacterial Antibiotic Resistance: The Most Critical Pathogens

Characterization and therapeutic potential of MRABP9, a novel lytic bacteriophage infecting multidrug-resistant Acinetobacter baumannii clinical strains

Acinetobacter baumannii is one of the most important pathogens of healthcare-associated infections. The rising prevalence of multidrug-resistant A. baumannii (MRAB) strains and biofilm formation impact the outcome of conventional treatment. Phage-related therapy is a promising strategy to tame troublesome multidrug-resistant bacteria. Here, we isolated and evaluated a highly efficient lytic phage called MRABP9 from hospital sewage. The phage was a novel species within the genus Friunavirus and exhibited lytic activity against 2 other identified MRAB strains. Genomic analysis revealed it was a safe virulent phage and a pectate lyase domain was identified within its tail spike protein. MRABP9 showed potent bactericidal and anti-biofilm activity against MRAB, significantly delaying the time point of bacterial regrowth in vitro. Phage administration could rescue the mice from acute lethal MRAB infection. Considering its features, MRABP9 has the potential as an efficient candidate for prophylactic and therapeutic use against acute infections caused by MRAB strains.

Gram-negative bacteria recognition and photodynamic elimination by Zn-DPA based sensitizers

The abuse and overuse of antibiotics let drug-resistant bacteria emerges. Antibacterial photodynamic therapy (APDT) has shown outstanding merits to eliminate the drug-resistant bacteria via cytotoxic reactive oxygen species produced by irradiating photosensitizer. However, most of photosensitizers are not effective for Gram-negative bacteria elimination. Herein conjugates of NBS, a photosensitizer, linked with one (NBS-DPA-Zn) or two (NBS-2DPA-Zn) equivalents of zinc-dipicolylamine (Zn-DPA) have been designed to achieve the functional recognition of different bacteria. Due to the cationic character of NBS and metal transfer channel effect of Zn-DPA, NBS-DPA-Zn exhibited the first regent to distinguish P. aeruginosa from other Gram-negative bacteria. Whereas NBS-2DPA-Zn showed broad-spectrum antibacterial effect because the two arm of double Zn-DPA enhanced interactions with anionic membranes of bacteria, led the bacteria aggregation and thus provided the efficacy of APDT to bacteria and corresponding biofilm. In combination with a hydrogel of Pluronic, NBS-2DPA-Zn@gel shows promising clinical application in mixed bacterial diabetic mouse model infection. This might propose a new method that can realize functional identification and elimination of bacteria through intelligent regulation of Zn-DPA, and shows excellent potential for antibacterial application.

The strongest protein binder is surprisingly labile

Bacterial adhesins are cell-surface proteins that anchor to the cell wall of the host. The first stage of infection involves the specific attachment to fibrinogen (Fg), a protein found in human blood. This attachment allows bacteria to colonize tissues causing diseases such as endocarditis. The study of this family of proteins is hence essential to develop new strategies to fight bacterial infections. In the case of the Gram-positive bacterium Staphylococcus aureus, there exists a class of adhesins known as microbial surface components recognizing adhesive matrix molecules (MSCRAMMs). Here, we focus on one of them, the clumping factor A (ClfA), which has been found to bind Fg through the dock-lock-latch mechanism. Interestingly, it has recently been discovered that MSCRAMM proteins employ a catch-bond to withstand forces exceeding 2 nN, making this type of interaction as mechanically strong as a covalent bond. However, it is not known whether this strength is an evolved feature characteristic of the bacterial protein or is typical only of the interaction with its partner. Here, we combine single-molecule force spectroscopy, biophysical binding assays, and molecular simulations to study the intrinsic mechanical strength of ClfA. We find that despite the extremely high forces required to break its interactions with Fg, ClfA is not by itself particularly strong. Integrating the results from both theory and experiments we dissect contributions to the mechanical stability of this protein.

The Rising Tide of Antibiotic Resistance: A Study on Extended-Spectrum Beta-Lactamase and Carbapenem-Resistant Escherichia coli and Klebsiella pneumoniae

BACKGROUND

The global spread of extended-spectrum beta-lactamase (ESBL)-producing and carbapenem-resistant Enterobacterales (CRE) poses a significant concern. Acquisition of antimicrobial resistance genes leads to resistance against several antibiotics, limiting treatment options. We aimed to study ESBL-producing and CRE transmission in clinical settings.

METHODS

From clinical samples, 227 ESBL-producing and CRE isolates were obtained. The isolates were cultured on bacterial media and confirmed by VITEK 2. Antibiograms were tested against several antibiotics using VITEK 2. The acquired resistance genes were identified by PCR.

RESULTS

Of the 227 clinical isolates, 145 (63.8%) were Klebsiella pneumoniae and 82 (36.1%) were Escherichia coli; 76 (33.4%) isolates were detected in urine, 57 (25.1%) in pus swabs, and 53 (23.3%) in blood samples. A total of 58 (70.7%) ESBL-producing E. coli were resistant to beta-lactams, except for carbapenems, and 17.2% were amikacin-resistant; 29.2% of E. coli isolates were resistant to carbapenems. A total of 106 (73.1%) ESBL-producing K. pneumoniae were resistant to all beta-lactams, except for carbapenems, and 66.9% to ciprofloxacin; 38 (26.2%) K. pneumoniae were resistant to carbapenems. Colistin emerged as the most effective antibiotic against both bacterial types. Twelve (20.6%) E. coli isolates were positive for blaCTX-M, 11 (18.9%) for blaTEM, and 8 (33.3%) for blaNDM. Forty-six (52.3%) K. pneumoniae isolates had blaCTX-M, 27 (18.6%) blaTEM, and 26 (68.4%) blaNDM.

CONCLUSION

This study found a high prevalence of drug-resistant ESBL-producing and CRE, highlighting the need for targeted antibiotic use to combat resistance.

A metabolomics pipeline highlights microbial metabolism in bloodstream infections

The growth of antimicrobial resistance (AMR) highlights an urgent need to identify bacterial pathogenic functions that may be targets for clinical intervention. Although severe infections profoundly alter host metabolism, prior studies have largely ignored microbial metabolism in this context. Here, we describe an iterative, comparative metabolomics pipeline to uncover microbial metabolic features in the complex setting of a host and apply it to investigate gram-negative bloodstream infection (BSI) in patients. We find elevated levels of bacterially derived acetylated polyamines during BSI and discover the enzyme responsible for their production (SpeG). Blocking SpeG activity reduces bacterial proliferation and slows pathogenesis. Reduction of SpeG activity also enhances bacterial membrane permeability and increases intracellular antibiotic accumulation, allowing us to overcome AMR in culture and in vivo. This study highlights how tools to study pathogen metabolism in the natural context of infection can reveal and prioritize therapeutic strategies for addressing challenging infections.

Bioinspired Nanotopography for Combinatory Osseointegration and Antibacterial Therapy

The ongoing global health has highlighted the critical issue of secondary infections, particularly antibiotic-resistant bacterial infections, which have been significant contributors to mortality rates. Orthopedic implants, while essential for trauma and orthopedic surgeries, are particularly susceptible to these infections, leading to severe complications and economic burdens. The traditional use of antibiotics in treating these infections poses further challenges including the risk of developing antibiotic-resistant bacteria. This study introduces a novel approach to combat this issue by developing nanostructured surfaces for orthopedic implants using target ion-induced plasma sputtering. Inspired by the natural design of dragonfly wings, these surfaces aim to prevent bacterial adhesion while promoting preosteoblast activity, offering a dual-function solution to the problems of bacterial infection and implant integration without relying on antibiotics. The in vitro results demonstrate the effectiveness of these bioinspired surfaces in eradicating bacteria and supporting cell proliferation and differentiation, presenting a promising alternative for the development of biomedical implants.

Keeping up with the pathogens: improved antimicrobial resistance detection and prediction from Pseudomonas aeruginosa genomes

BACKGROUND

Antimicrobial resistance (AMR) is an intensifying threat that requires urgent mitigation to avoid a post-antibiotic era. Pseudomonas aeruginosa represents one of the greatest AMR concerns due to increasing multi- and pan-drug resistance rates. Shotgun sequencing is gaining traction for in silico AMR profiling due to its unambiguity and transferability; however, accurate and comprehensive AMR prediction from P. aeruginosa genomes remains an unsolved problem.

METHODS

We first curated the most comprehensive database yet of known P. aeruginosa AMR variants. Next, we performed comparative genomics and microbial genome-wide association study analysis across a Global isolate Dataset (n = 1877) with paired antimicrobial phenotype and genomic data to identify novel AMR variants. Finally, the performance of our P. aeruginosa AMR database, implemented in our AMR detection and prediction tool, ARDaP, was compared with three previously published in silico AMR gene detection or phenotype prediction tools-abritAMR, AMRFinderPlus, ResFinder-across both the Global Dataset and an analysis-naïve Validation Dataset (n = 102).

RESULTS

Our AMR database comprises 3639 mobile AMR genes and 728 chromosomal variants, including 75 previously unreported chromosomal AMR variants, 10 variants associated with unusual antimicrobial susceptibility, and 281 chromosomal variants that we show are unlikely to confer AMR. Our pipeline achieved a genotype-phenotype balanced accuracy (bACC) of 85% and 81% across 10 clinically relevant antibiotics when tested against the Global and Validation Datasets, respectively, vs. just 56% and 54% with abritAMR, 58% and 54% with AMRFinderPlus, and 60% and 53% with ResFinder. ARDaP's superior performance was predominantly due to the inclusion of chromosomal AMR variants, which are generally not identified with most AMR identification tools.

CONCLUSIONS

Our ARDaP software and associated AMR variant database provides an accurate tool for predicting AMR phenotypes in P. aeruginosa, far surpassing the performance of current tools. Implementation of ARDaP for routine AMR prediction from P. aeruginosa genomes and metagenomes will improve AMR identification, addressing a critical facet in combatting this treatment-refractory pathogen. However, knowledge gaps remain in our understanding of the P. aeruginosa resistome, particularly the basis of colistin AMR.

Comprehensive insights into Klebsiella pneumoniae: unravelling clinical impact, epidemiological trends and antibiotic-resistance challenges

Klebsiella pneumoniae, a challenging opportunistic bacterium, became a notable global health concern owing to its clinical impact, widespread epidemiology and escalating antibiotic resistance. This comprehensive review delves into the multifaceted dimensions of K. pneumoniae, with a focus on its clinical implications, epidemiological patterns and the critical issue of antibiotic resistance. The review also emphasizes the implications of K. pneumoniae in the context of antimicrobial stewardship and infection control. Epidemiological aspects are scrutinized, shedding light on the global distribution and prevalence of K. pneumoniae. Factors influencing its transmission and persistence in healthcare facilities and communities are examined, with patient demographics, healthcare practices and geographical variations. The review centres on antibiotic resistance, a critical issue in the era of bacteria displaying resistance to multiple drugs. The mechanisms of resistance used by K. pneumoniae against various classes of antibiotics are elucidated, along with the alarming rise of carbapenem-resistant strains. It also highlights ongoing research efforts and innovative strategies aimed at addressing this critical public health issue. This comprehensive review offers a holistic understanding of K. pneumoniae, emphasizing its clinical significance, global epidemiology and the immediate necessity for effective strategies to combat antibiotic resistance. It serves as a valuable resource for healthcare practitioners, researchers and policymakers seeking to manage better and mitigate the impact of this pathogen on public health.

Biofilm Formation by Hospital-Acquired Resistant Bacteria Isolated from Respiratory Samples

BACKGROUND

Hospital-acquired resistant infections (HARI) are infections, which develop 48 h or more after admission to a healthcare facility. HARI pose a considerably acute challenge, due to limited treatment options. These infections are associated bacterial biofilms, which act as a physical barrier to diverse external stresses, such as desiccation, antimicrobials and biocides. We assessed the influence of multiple factors on biofilm production by HARI -associated bacteria.

METHODS

Bacteria were isolated from samples of patients with respiratory HARI who were hospitalized during 2020-2022 in north Israel. Following antibiotic susceptibility testing by disc diffusion or broth microdilution, biofilm formation capacities of resistant bacteria (methicillin-resistant staphylococcus aureus, extended spectrum beta-lactamase-producing Escherichia coli and Klebsiela pneumonia, and multidrug-resistant Pseudomonas aeruginosa and Acinetobacter baumannii) was assessed using the crystalline violet staining method. Data regarding season, time to infection, bacterial species, patient age and gender, year, and medical department were collected from the patient medical records.

RESULTS

Among the 226 study isolates, K. pneumonia was the most prevalent (35.4%) bacteria, followed by P. aeruginosa (23.5%), and methicillin-resistant staphylococcus aureus (MRSA) (21.7%). A significantly higher rate of HARI was documented in 2022 compared to 2020-2021. The majority of isolates (63.3%) were strong biofilm producers, with K. pneumonia (50.3%) being most dominant, followed by P. aeruginosa (29.4%). Biofilm production strength was significantly affected by seasonality and hospitalization length, with strong biofilm production in autumn and in cases where hospitalization length exceeded 30 days.

CONCLUSION

Biofilm production by HARI bacteria is influenced by bacterial species, season and hospitalization length.

Construction of atom co-sharing Bi/Bi4O5Br2 nanosheet heterojunction for plasmonic-enhanced visible-light-driven photocatalytic antibacterial activity

The rapid advancement of photodynamic therapy (PDT) antibacterial materials has led to promising alternatives to antibiotics for treating bacterial infections. However, antibacterial drugs have poor light absorption and utilization rates, which limits their practical application. Constructing two-dimensional (2D) heterojunctions from materials with matching photophysical properties has emerged as a highly effective strategy for achieving high-efficiency photo-antibacterial performance. Here, we designed and prepared an atom co-sharing Bi/Bi4O5Br2 nanosheet heterojunction by a simple in situ reduction. This heterojunction material combines outstanding biocompatibility with excellent bactericidal efficiency, which exceeded 90 % against Escherichia coli (a Gram-negative bacterium) and Staphylococcus aureus (a Gram-positive bacterium) under visible light irradiation, around nine-fold higher than that with pure Bi4O5Br2 nanosheets. The results suggest that localized surface plasmon resonance (LSPR) of shared Bi atoms on the Bi4O5Br2 nanosheets promotes light utilization and the separation and transfer of photo-generated charges, thus producing more abundant reactive oxygen species (ROS), which can partake in the PDT antibacterial effect. Our study underscores the potential utility of LSPR-enhanced Bi-based nanosheet heterojunctions for safe and efficient PDT to combat bacterial infections.

In vitro activity of ceftazidime-avibactam against gram-negative bacteria in patients with bacteremia and skin and soft-tissue infections in Colombia 2019-2021

OBJECTIVES

Ceftazidime-avibactam (CAZ-AVI) is an option for infections caused by MDR gram-negative bacilli. In this study, we aimed to analyze the in vitro antimicrobial activity of CAZ-AVI and other antimicrobial agents against gram-negative bacilli that were collected in Colombia between 2019 and 2021 from patients with bacteremia and skin and soft-tissue infections (SSTIs).

METHODS

A total of 600 Enterobacterales and 259 P. aeruginosa strains were analyzed. The phenotypic resistance of isolates, particularly non-susceptibility to meropenem, multidrug-resistant (MDR) isolates, and difficult-to-treat (DTR) P. aeruginosa, was evaluated according to CLSI breakpoints.

RESULTS

Enterobacterales had the most susceptibility to CAZ-AVI (96.5 %) and tigecycline (95 %). Tigecycline and CAZ-AVI were the antimicrobial agents with the most in vitro activity against carbapenem-resistant Enterobacterales (CRE). CAZ-AVI was the antimicrobial treatment with the most activity against P. aeruginosa.

CONCLUSIONS

Tigecycline and CAZ-AVI were the antimicrobial agents with the most activity against CRE and MDR Enterobacterales. For P. aeruginosa, CAZ-AVI was the antimicrobial treatment with the most in vitro activity.

Local anesthetics as a tool for Staphylococcus spp. control: a systematic review

The objective of this work was to carry out a systematic review on the effectiveness of local anesthetics as antimicrobial agents against Staphylococcus spp. Searches were performed in the PubMed, Web of science, Scopus, Embase and Lilacs databases. As inclusion criteria, complete original articles, with in vitro experimental tests with the application of selected anesthetics and bacteria of the genus Staphylococcus spp. This review followed the methodological checklist for writing papers reporting systematic reviews by the PRISMA statement. The risk of bias was assessed according to the JBI critical appraisal checklist. Analysis was performed using an anesthetic-moderated simple linear regression model. This systematic review was registered by the Open Science Framework-OSF ( https://doi.org/10.17605/OSF.IO/C5JM7 ). Initially, 1141 articles were found, of which, after careful selection, 52 articles were analyzed. Lidocaine was the most commonly used anesthetic, being evaluated in 35 of the articles. S. aureus ATCC 25923 was the standard microorganism in 17 articles. The impact of the anesthetic concentration in relation to the antimicrobial effect was evaluated and the results showed that there was no statistically significant difference. (F [5, 12] = 0.688 p = 0.642), even when taking into account the moderator effect of anesthetics individually. Therefore, although the antimicrobial effect of local anesthetics was demonstrated in 82.7% of the studies evaluated, great heterogeneity of the results was found, which made it impossible to carry out a meta-analysis and make recommendations based on the evidence.

Ceftazidime-Avibactam in the Treatment of Patients with Bacteremia or Nosocomial Pneumonia: A Systematic Review and Meta-analysis

INTRODUCTION

Ceftazidime-avibactam (CAZ-AVI) is a combination of the third-generation cephalosporin ceftazidime and the novel, non-β-lactam β-lactamase inhibitor avibactam that is approved for the treatment of pediatric (≥ 3 months) and adult patients with complicated infections including hospital-acquired and ventilator-associated pneumonia (HAP/VAP), and bacteremia. This systematic literature review and meta-analysis (PROSPERO registration: CRD42022362856) aimed to provide a quantitative and qualitative synthesis to evaluate the effectiveness of CAZ-AVI in treating adult patients with bacteremia or nosocomial pneumonia caused by carbapenem-resistant Enterobacterales (non metallo-β-lactamase-producing strains) and multi-drug resistant (MDR) Pseudomonas aeruginosa infections.

METHODS

The databases included in the search, until November 7, 2022, were Embase and PubMed. A total of 24 studies (retrospective: 22, prospective: 2) with separate outcomes for patients with bacteremia or pneumonia were included.

RESULTS

The outcomes assessed were all-cause mortality, clinical cure, and microbiological cure. Qualitative (24 studies) and quantitative (8/24 studies) syntheses were performed. The quality of the studies was assessed using the MINORS checklist and the overall risk of bias was moderate to high.

CONCLUSIONS

In studies included in the meta-analysis, lower all-cause mortality for patients with bacteremia (OR = 0.30, 95% CI 0.19-0.46) and improved rates of clinical cure for patients with bacteremia (OR = 4.90, 95% CI 2.60-9.23) and nosocomial pneumonia (OR = 3.20, 95% CI 1.55-6.60) was observed in the CAZ-AVI group compared with the comparator group. Data provided here may be considered while using CAZ-AVI for the treatment of patients with difficult-to-treat infections.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42022362856.

Verapamil increases susceptibility of colistin-resistant Acinetobacter baumannii to colistin

Acinetobacter baumannii, which is predominantly responsible for hospital-acquired infections, presents a tremendous clinical challenge due to its increasing antibiotic resistance to colistin (COL), a last-line antibiotic. As a result, the combination of antimicrobial and non-antimicrobial agents is emerging as a more popular treatment approach against infections caused by colistin-resistant (COL-R) A. baumannii. This study administered COL and verapamil (VER), i.e., an antihypertensive and antiarrhythmic agent. We found that the susceptibility of A. baumannii to COL was restored both in vitro and in vivo. Scanning electron microscope (SEM) and Crystal violet staining showed inhibition of the VER/COL combination on bacterial biofilm formation. Cytotoxicity assay and hemolysis test were used to confirm in vitro safety evaluation. Further experiments using propidium iodide (PI) staining revealed that the VER/COL combination improved the therapeutic efficacy of COL by modifying the permeability of bacterial membranes. As demonstrated by Reactive Oxygen Species (ROS) experiments, the drug combination caused the accumulation of bacterial ROS and their eventual death. Additionally, VER/COL treatment significantly reduced the efflux of Rhodamine 123 (Rh123). For the first time, this study identifies the anti-hypertensive drug VER as a COL potentiator against A. baumannii, providing a potential treatment approach against A. baumannii infections and improving patient outcomes.

Chitosan/Alginate-Based Nanoparticles for Antibacterial Agents Delivery

Nanoparticle systems integrating alginate and chitosan emerge as a promising avenue to tackle challenges in leveraging the potency of pharmacological active agents. Owing to their intrinsic properties as polysaccharides, alginate and chitosan, exhibit remarkable biocompatibility, rendering them conducive to bodily integration. By downsizing drug particles to the nano-scale, the system enhances drug solubility in aqueous environments by augmenting surface area. Additionally, the system orchestrates extended drug release kinetics, aligning well with the exigencies of chronic drug release requisite for antibacterial therapeutics. A thorough scrutiny of existing literature underscores a wealth of evidence supporting the utilization of the alginate-chitosan nanoparticle system for antibacterial agent delivery. Literature reviews present abundant evidence of the utilization of nanoparticle systems based on a combination of alginate and chitosan for antibacterial agent delivery. Various experiments demonstrate enhanced antibacterial efficacy, including an increase in the inhibitory zone diameter, improvement in the minimum inhibitory concentration, and an enhancement in the bacterial reduction rate. This enhancement in efficacy occurs due to mechanisms involving increased solubility resulting from particle size reduction, prolonged release effects, and enhanced selectivity towards bacterial cell walls, stemming from ionic interactions between positively charged particles and teichoic acid on bacterial cell walls. However, clinical studies remain limited, and there are currently no marketed antibacterial drugs utilizing this system. Hence, expediting clinical efficacy validation is crucial to maximize its benefits promptly.

Synergistic inhibition of ureolytic activity and growth of Klebsiella pneumoniae in vitro suggests cobinding of fluoride and acetohydroxamic acid at the urease active site and provides a novel strategy to combat ureolytic bacteria

The ability of ureolytic bacteria to break down stable urea to alkaline ammonia leads to several environmental and health challenges. Ureolytic bacteria such as Helicobacter pylori, Klebsiella pneumoniae, and Proteus mirabilis can become pathogenic and cause persistent infections that can be difficult to treat. Inhibiting urease activity can reduce the growth and pathogenicity of ureolytic bacteria. In the present in vitro study, we investigated the synergistic effects of tannic acid (TA) and the urease inhibitors fluoride (F-) and acetohydroxamic acid (AHA). The concentration of AHA needed for efficient inhibition of the ureolytic activity of K. pneumoniae can be significantly reduced if AHA is coapplied with tannic acid and sodium fluoride (NaF). Thus, only 1.20 μmol l-1 AHA in combination with 0.30 mmol l-1 tannic acid and 0.60 mmol l-1 NaF delayed the onset of ureolytic pH increase by 95.8 % and increased the growth lag phase by 124.3 % relative to untreated K. pneumoniae. At these concentrations, without AHA, TA and NaF increased the onset of the ureolytic pH change by only 37.0 % and the growth lag phase by 52.5 %. The strong inhibition obtained with low concentrations of AHA in triple-compound treatments suggests cobinding of F- and AHA at the urease active site and could reduce the side effects of AHA when it is employed as a drug against e.g. urinary tract infections (UTIs) and blocked catheters. This study reports the basis for a promising novel therapeutic strategy to combat infections caused by ureolytic bacteria and the formation of urinary tract stones and crystalline biofilms on catheters.

Investigating the anti-growth, anti-resistance, and anti-virulence activities of Schoepfia schreberi J.F.Gmel. against the superbug Acinetobacter baumannii

Schoepfia schreberi has been used in Mayan folk medicine to treat diarrhea and cough. This study aimed to determine the anti-growth, anti-resistance, and/or anti-virulence activities of S. schreberi extracts against Acinetobacter baumannii, a pathogen leader that causes healthcare-associated infections with high rates of drug-resistant including carbapenems, the last line of antibiotics known as superbugs, and analyze their composition using HPLC-DAD. Ethyl acetate (SSB-3) and methanol (SSB-4) bark extracts exhibit antimicrobial and biocidal effects against drug-susceptible and drug-resistant A. baumannii. Chemical analysis revealed that SSB-3 and SSB-4 contained of gallic and ellagic acids derivatives. The anti-resistance activity of the extracts revealed that SSB-3 or SSB-4, combined with imipenem, exhibited potent antibiotic reversal activity against A. baumannii by acting as pump efflux modulators. The extracts also displayed activity against surface motility of A. baumannii and its capacity to survive reactive oxygen species. This study suggests that S. schreberi can be considered a source of antibiotics, even adjuvanted compounds, as anti-resistant or anti-virulence agents against A. baumannii, contributing to ethnopharmacological knowledge and reappraisal of Mayan medicinal flora, and supporting the traditional use of the bark of the medicinal plant S. schreberi for the treatment of infectious diseases.

Ultrathin TiS2@N,S-Doped Carbon Hybrid Nanosheets as Highly Efficient Photoresponsive Antibacterial Agents

Nanobactericides are employed as a promising class of nanomaterials for eradicating microbial infections, considering the rapid resistance risks of conventional antibiotics. Herein, we present a pioneering approach, reporting the synthesis of two-dimensional titanium disulfide nanosheets coated by nitrogen/sulfur-codoped carbon nanosheets (2D-TiS2@NSCLAA hybrid NSs) using a rapid l-ascorbic acid-assisted sulfurization of Ti3C2Tx-MXene to achieve efficient alternative bactericides. The as-developed materials were systematically characterized using a suite of different spectroscopy and microscopy techniques, in which the X-ray diffraction/Raman spectroscopy/X-ray photoelectron spectroscopy data confirm the existence of TiS2 and C, while the morphological investigation reveals single- to few-layered TiS2 NSs confined by N,S-doped C, suggesting the successful synthesis of the ultrathin hybrid NSs. From in vitro evaluation, the resultant product demonstrates impressive bactericidal potential against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria, achieving a substantial decrease in the bacterial viability under a 1.2 J dose of visible-light irradiation at the lowest concentration of 5 μg·mL-1 compared to Ti3C2Tx (15 μg·mL-1), TiS2-C (10 μg·mL-1), and standard antibiotic ciprofloxacin (15 μg·mL-1), respectively. The enhanced degradation efficiency is attributed to the ultrathin TiS2 NSs encapsulated within heteroatom N,S-doped C, facilitating effective photogenerated charge-carrier separation that generates multiple reactive oxygen species (ROS) and induced physical stress as well as piercing action due to its ultrathin structure, resulting in multimechanistic cytotoxicity and damage to bacterial cells. Furthermore, the obtained results from molecular docking studies conducted via computational simulation (in silico) of the as-synthesized materials against selected proteins (β-lactamasE. coli/DNA-GyrasE. coli) are well-consistent with the in vitro antibacterial results, providing strong and consistent validation. Thus, this sophisticated study presents a simple and effective synthesis technique for the structural engineering of metal sulfide-based hybrids as functionalized synthetic bactericides.

In silico-designed antimicrobial peptide targeting MRSA and E. coli with antibacterial and antibiofilm actions

Antibiotic resistance is a paramount global health issue, with numerous bacterial strains continually fortifying their resistance against diverse antibiotics. This surge in resistance levels primarily stems from the overuse and misuse of antibiotics in human, animal, and environmental contexts. In this study, we advocate for exploring alternative molecules exhibiting antibacterial properties to counteract the escalating antibiotic resistance. We identified a synthetic antimicrobial peptide (AMP) by using computational search in AMP public databases and further engineering through molecular docking and dynamics. Microbiological evaluation, cytotoxicity, genotoycity, and hemolysis experiments were then performed. The designed AMP underwent rigorous testing for antibacterial and antibiofilm activities against Methicillin-Resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli), representing gram-positive and gram-negative bacteria, respectively. Subsequently, the safety profile of the AMP was assessed in vitro using human fibroblast cells and a human blood sample. The selected AMP demonstrated robust antibacterial and antibiofilm efficacy against MRSA and E. coli, with an added assurance of non-cytotoxicity and non-genotoxicity towards human fibroblasts. Also, the AMP did not demonstrate any hemolytic activity. Our findings emphasize the considerable promise of the AMP as a viable alternative antibacterial agent, showcasing its potential to combat antibiotic resistance effectively.

Exploring the Application of Metagenomic Next-Generation Sequencing in the Diagnosis of Unexplained Pulmonary Infection

Background

Pulmonary infections are significant global health burdens, and conventional diagnostic methods (culture and polymerase chain reaction), are often limited by slow results and low sensitivity. Metagenomic next-generation sequencing (mNGS) offers a rapid, comprehensive alternative for identifying diverse pathogens, including rare and mixed infections. Thus, we assessed the diagnostic performance of mNGS in pulmonary infections, compared the findings with those of traditional pathogen detection methods, and explored its potential to enhance clinical diagnostics and patient care.

Methods

We collected samples from 125 immunocompromised patients diagnosed with pulmonary infection at the Department of Respiratory Medicine of Shenzhen Longgang Central Hospital from March 2020 to July 2022. We compared the rate of pathogen positivity and pathogen distribution between conventional pathogen detection methods and mNGS using samples including sputum, blood, and bronchoalveolar lavage fluid.

Results

Among the 125 cases of unexplained pulmonary infection, 82 (65.6%) and 40 (32.0%) tested positive for pathogens using mNGS and routine culture, respectively (P < 0.05). Both methods of pathogen detection were positive in 28 (22.4%) cases (complete match, 9; complete mismatch, 13; partial match, 6). However, 43.2% of cases only tested positive using mNGS, 9.4% only tested positive using routine tests, and 24.8% tested negative using both methods. A viral infection was present in 55.2% of cases. The detection rate of mycobacteria using mNGS (12.8%) was higher than that using conventional pathogen detection methods (5.6%).

Conclusion

mNGS technology enhances pathogen detection in unexplained pulmonary infections, enabling targeted antimicrobial therapy and consequently helping to reduce broad-spectrum antibiotic use, aligning treatments more closely with the causative pathogens. Thus, mNGS offers significant clinical value by improving treatment efficacy and potentially reducing antibiotic resistance in pulmonary infection cases.

Probiotics for Aquaculture: Hope, Truth, and Reality

The use of microorganisms as beneficial crops for human and animal health has been studied for decades, and these microorganisms have been in practical use for quite some time. Nowadays, in addition to well-known examples of beneficial properties of lactic acid bacteria, bifidobacteria, selected Bacillus spp., and yeasts, there are several other bacteria considered next-generation probiotics that have been proposed to improve host health. Aquaculture is a rapidly growing area that provides sustainable proteins for consumption by humans and other animals. Thus, there is a need to develop new technologies for the production practices associated with cleaner and environment-friendly approaches. It is a well-known fact that proper selection of the optimal probiotics for use in aquaculture is an essential step to ensure effectiveness and safety. In this critical review, we discuss the evaluation of host-specific probiotics in aquaculture, challenges in using probiotics in aquaculture, methods to improve the survival of probiotics under different environmental conditions, technological approach to improving storage, and delivery along with possible negative consequences of using probiotics in aquaculture. A critical analysis of the identified challenges for the use of beneficial microbes in aquaculture will help in sustainable aquafarming, leading to improved agricultural practices with a clear aim to increase protein production.

Recent Advances in Amphipathic Peptidomimetics as Antimicrobial Agents to Combat Drug Resistance

The development of antimicrobial drugs with novel structures and clear mechanisms of action that are active against drug-resistant bacteria has become an urgent need of safeguarding human health due to the rise of bacterial drug resistance. The discovery of AMPs and the development of amphipathic peptidomimetics have lay the foundation for novel antimicrobial agents to combat drug resistance due to their overall strong antimicrobial activities and unique membrane-active mechanisms. To break the limitation of AMPs, researchers have invested in great endeavors through various approaches in the past years. This review summarized the recent advances including the development of antibacterial small molecule peptidomimetics and peptide-mimic cationic oligomers/polymers, as well as mechanism-of-action studies. As this exciting interdisciplinary field is continuously expanding and growing, we hope this review will benefit researchers in the rational design of novel antimicrobial peptidomimetics in the future.

Risk factors and economic burden for community-acquired multidrug-resistant organism-associated urinary tract infections: A retrospective analysis

The spread of multidrug-resistant organisms (MDROs) has resulted in a corresponding increase in the incidence of urinary tract infections (UTIs). The risk factors and hospitalization burden for community-acquired MDRO-associated UTIs are discussed herein. This retrospective study included 278 patients with community-based MDRO-associated UTIs from January 2020 to January 2022. The MDRO (n = 139) and non-MDRO groups (n = 139) were separated based on drug susceptibility results. Community-based MDRO-associated UTIs mainly occurred in the elderly and frail patients with a history of invasive urinary tract procedures. The MDRO group imposed a greater economic burden compared to the non-MDRO group. Independent risk factors for community-based MDRO-associated UTIs were as follows: white blood cell (WBC) count > 10.0 × 109/L (OR = 2.316, 95% CI = 1.316-3.252; P = .018); ≥3 kinds of urinary tract obstructive diseases (OR = 1.720, 95% CI = 1.004-2.947; P = .048); use of 3rd generation cephalosporins (OR = 2.316, 95% CI = 1.316-4.076; P = .004); and a history of invasive urologic procedures (OR = 2.652, 95% CI = 1.567-4.487; P < .001). Days of hospitalization, antibiotic use, and bladder catheter use were significantly greater in the MDRO group than the non-MDRO group (P < .05).

Exploring the physicochemical traits, antifungal capabilities, and 3D spatial complexity of hydroxyapatite with Ag+Mg2+ substitution in the biocomposite thin films

The silver/magnesium doped hydroxyapatite (AgMgHAp, Ca10-x-yAgxMgy(PO4)6(OH)2, xAg=0.05 and yMg=0.02) nanocomposites coatings were deposited on Si substrate using the dip coating technique. The resulting coatings were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FTIR-ATR) spectroscopy, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The EDS analysis highlighted the presence of the constitutive elements of the silver/magnesium doped hydroxyapatite (AgMgHAp) nanocomposites coatings. The surface microtexture of the AgMgHAp was assessed by atomic force microscopy (AFM) technique. The AFM data suggested the obtaining of a uniform deposited layer comprised of equally distributed nanoconglomerates. FT-IR studies highlighted the presence of vibrational modes associated with the phosphate and hydroxyl groups. No bands associated with silver or magnesium were observed. The XPS analysis highlighted the presence of the constituent elements of hydroxyapatite (Ca 2p, P 2 s, O 1 s), as well as dopants (Ag 3d, Mg 1 s and Mg 2p). The antifungal evaluation of AgMgHAp coatings was carried out using the Candida albicans ATCC 10231 fungal strain. The results of the antifungal assay revealed that the AgMgHAp coatings exhibited a strong inhibitory antifungal activity. Furthermore, the data highlighted that the AgMgHAp inhibited the development of biofilm on their surface. The results revealed that the antifungal activity of the coating varied based on the duration of incubation. On the other hand, the data also showed that AgMgHAp nanocomposites coatings inhibited the fungal cell adhesion and development from the early stages of the incubation. In addition to morphological analysis, we additionally take advantage of AFM images to investigate and explore the domain of fractal and multifractal analysis applied to the films under evaluation. Our studies indicates that nanocomposite coatings made from AgMgHAp demonstrate strong antifungal properties. Our studies indicates that nanocomposite coatings made from AgMgHAp demonstrate strong antifungal properties. These results suggest the potential of AgMgHAp nanocomposite coatings as a promising solution for developing innovative antifungal devices in biomedical applications.

New quinazolin-2,4-dione derivatives incorporating acylthiourea, pyrazole and/or oxazole moieties as antibacterial agents via DNA gyrase inhibition

This article contributes to the search for new therapeutic agents for treatment of diseases caused by bacterial pathogens. In this study, a new series of compounds incorporating numerous bioactive moieties such as quinazolin-2,4-dione, acylthiourea linkage, and/or five membered nitrogen heterocycles (pyrazole and oxazole) 2-5a-c was described to identify new antibacterial drug candidates via inhibition of DNA gyrase enzyme. The precursor N-[N'-(2-cyano-acetyl)-hydrazinocarbothioyl]-4-(2,4-dioxo-1,4-dihydro-2H-quinazolin-3-yl)-benzamide 2 was prepared by treatment of compound 1 with ammonium thiocyanate and cyanoacetic acid hydrazide through multicomponent reaction (MCR). In addition, compounds 3a-d and 4a-b were synthesized by treatment of 2 with aromatic aldehydes and/or ketones through Knoevenagel reaction, affording high purity products in satisfactory yields. Moreover, new heterocyclic moieties such as pyrazole and/or oxazole attached to quinazolin-2,4-dione core 5a-c were synthesized by treatment of 3c with different nucleophilic reagents like hydrazine, phenyl hydrazine and hydroxyl amine, respectively. Subsequently, the obtained products were structurally characterized by IR, 1H-, 13C-NMR, and MS analyses. The minimum inhibitory concentration (MIC) and antibacterial potency of all compounds were estimated against two G-ve (E. coli and P. aeruginosa), and two G+ve bacteria (B. subtilis and S. aureus). Encouragingly, compound 3c demonstrated the best antibacterial activity against all the strains of the tested pathogenic bacteria at low concentrations compared with the standard drug, Ciprofloxacin. Electron withdrawing groups such as -NO2 and -Cl enhance the antibacterial activity. Next, a molecular docking study between the synthesized derivatives and the target enzyme, DNA gyrase enzyme (PDB: 2xct) was undertaken to investigate intermolecular interactions between the compounds and target enzyme.

Genetic relatedness, antibiotic resistance, and virulence of Klebsiella pneumoniae isolated from healthcare and food sources in Wuhan, China

OBJECTIVE

To investigate genetic relatedness and antibiotic resistance of Klebsiella pneumoniae from retail meat samples, clinical source samples, and hospital environmental samples in Wuhan, China.

METHODS

The hypermucoviscosity phenotypes and biofilm formation ability of K. pneumoniae were determined by string test and crystalline violet staining. The minimal inhibitory concentrations of 18 antimicrobial agents were determined by the broth microdilution test, and PCR assays were performed to detect 14 genes associated with antibiotic resistance. Pulsed-field gel electrophoresis (PFGE) analysis was used to assess the genetic relatedness and clonal dissemination.

RESULTS

Among the 5730 samples analyzed, 46 tested positive for K. pneumoniae, with higher rates observed in meat (23.4%, CI: 12.8-38.4%) than in clinical samples (0.6%, CI: 0.4-0.8%) and hospital environmental samples (8.0%, CI: 2.6-20.1%). Meat-derived isolates showed high resistance to tetracycline (36.4%, 4/11, CI: 12.4-68.4%), sulphonamide (27.3%, 3/11, CI: 7.3-60.7%), and gentamicin (27.3%, 3/11, CI: 7.3-60.7%), whereas clinical isolates exhibited significant resistance to ampicillin-sulbactam (32.3%, 10/31, CI: 17.3-51.5%). Multidrug resistance was observed in 17.4% (8/46, CI:8.3-32.0%) of the isolates, particularly in hospital environmental samples (3/4, CI: 21.9-98.7%). Biofilm production was observed in 88.1% (37/42, CI: 73.6-95.6%) of K. pneumoniae, with varying degrees of strength. PFGE analysis revealed patient-to-patient K. pneumoniae transmission, transmission between patients and hospital environment, as well as cross-contamination between markets.

CONCLUSION

The findings underscore the importance of comprehensive surveillance, infection control and judicious antibiotic use in mitigating the impact of K. pneumoniae on public health, especially in food chain and healthcare settings.

Antibacterial and Antibiofilm Potential of Bacterial Cellulose Hydrogel Containing Vancomycin against Multidrug-Resistant Staphylococcus aureus and Staphylococcus epidermidis

The present study aimed to evaluate the in vitro antibacterial and antibiofilm activity of bacterial cellulose hydrogel produced by Zoogloea sp. (HYDROGEL) containing vancomycin (VAN) against bacterial strains that cause wound infections, such as multidrug-resistant (MDR) Staphylococcus aureus and Staphylococcus epidermidis. Initially, HYDROGEL was obtained from sugar cane molasses, and scanning electron microscopy (SEM) was performed to determine morphological characteristics. Then, VAN was incorporated into HYDROGEL (VAN-HYDROGEL). The antibacterial activity of VAN, HYDROGEL, and VAN-HYDROGEL was assessed using the broth microdilution method to determine the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) against methicillin-sensitive S. aureus (MSSA) ATCC 25923, methicillin-resistant S. aureus (MRSA) ATCC 33591, S. epidermidis INCQS 00016 (ATCC 12228), five clinical isolates of MRSA, and nine clinical isolates of methicillin-resistant S. epidermidis, following the Clinical and Laboratory Standards Institute (CLSI) guidelines. Additionally, the antibacterial activity of VAN, HYDROGEL, and VAN-HYDROGEL was studied using the time-kill assay. Subsequently, the antibiofilm activity of VAN, HYDROGEL, and VAN-HYDROGEL was evaluated using crystal violet and Congo red methods, as well as SEM analysis. VAN and VAN-HYDROGEL showed bacteriostatic and bactericidal activity against MRSA and methicillin-resistant S. epidermidis strains. HYDROGEL did not show any antibacterial activity. Analysis of the time-kill assay indicated that HYDROGEL maintained the antibacterial efficacy of VAN, highlighting its efficiency as a promising carrier. Regarding antibiofilm activity, VAN and HYDROGEL inhibited biofilm formation but did not demonstrate biofilm eradication activity against methicillin-resistant S. aureus and S. epidermidis strains. However, it was observed that the biofilm eradication potential of VAN was enhanced after incorporation into HYDROGEL, a result also proven through images obtained by SEM. From the methods carried out in this study, it was possible to observe that HYDROGEL preserved the antibacterial activity of vancomycin, aside from exhibiting antibiofilm activity and enhancing the antibiofilm effect of VAN. In conclusion, this study demonstrated the potential of HYDROGEL as a candidate and/or vehicle for antibiotics against MDR bacteria that cause wound infections.

Pseudomonas aeruginosa Isolates from Water Samples of the Gulf of Mexico Show Similar Virulence Properties but Different Antibiotic Susceptibility Profiles than Clinical Isolates

Pseudomonas aeruginosa is an opportunistic pathogen found in a wide variety of environments, including soil, water, and habitats associated with animals, humans, and plants. From a One Health perspective, which recognizes the interconnectedness of human, animal, and environmental health, it is important to study the virulence characteristics and antibiotic susceptibility of environmental bacteria. In this study, we compared the virulence properties and the antibiotic resistance profiles of seven isolates collected from the Gulf of Mexico with those of seven clinical strains of P. aeruginosa. Our results indicate that the marine and clinical isolates tested exhibit similar virulence properties; they expressed different virulence factors and were able to kill Galleria mellonella larvae, an animal model commonly used to analyze the pathogenicity of many bacteria, including P. aeruginosa. In contrast, the clinical strains showed higher antibiotic resistance than the marine isolates. Consistently, the clinical strains exhibited a higher prevalence of class 1 integron, an indicator of anthropogenic impact, compared with the marine isolates. Thus, our results indicate that the P. aeruginosa marine strains analyzed in this study, isolated from the Gulf of Mexico, have similar virulence properties, but lower antibiotic resistance, than those from hospitals.

Polyphenolic compounds in the combat of foodborne infections - An update on recent evidence

In recent years, the incidence of food-borne bacterial enteric diseases has increased worldwide causing significant health care and socioeconomic burdens. According to the World Health Organization, there are an estimated 600 million cases of foodborne illnesses worldwide each year, resulting in 420,000 deaths. Despite intensive efforts to tackle this problem, foodborne pathogenic microorganisms continue to be spread further. Therefore, there is an urgent need to find novel anti-microbial non-toxic compounds for food preservation. One way to tackle this issue may be the usage of polyphenols, which have received increasing attention in the recent years given their pleotropic health-promoting properties. This prompted us to perform a literature search summarizing studies from the past 10 years regarding the potential anti-microbial and disease-alleviating effects of plant-derived phenolic compounds against foodborne bacterial pathogens. The included 16 studies provide evidence that polyphenols show pronounced anti-bacterial and anti-oxidant effects against both Gram-positive and Gram-negative bacterial species. In addition, synergistic anti-microbial effects in combination with synthetic antibiotics were observed. In conclusion, phenolic compounds may be useful as natural anti-microbial agents in the food, agricultural, and pharmaceutical industries in the combat of foodborne infections.

Antibacterial, Trichomonacidal, and Cytotoxic Activities of Pleopeltis crassinervata Extracts

Pleopeltis crassinervata is a fern documented in ethnobotanical records for its use in Mexican traditional medicine to treat gastric disorders and mouth ulcers. Consequently, conducting biological and pharmacological assays is crucial to validate the therapeutic efficacy of this plant within the context of traditional medicine. In the present study, we investigated the biological activity of extracts and fractions obtained from P. crassinervata organs against bacteria (Salmonella typhimurium, Salmonella typhi, Staphylococcus aureus, Proteus mirabilis, Shigella flexneri, Bacillus subtilis, Escherichia coli) and Trichomonas vaginalis using in vitro models. The precipitate fraction obtained from the frond methanolic extract showed significant antibacterial activity (minimal inhibitory concentration [MIC] 120 µg/mL) against the Staphylococcus aureus strain and was effective against both Gram-positive and Gram-negative bacteria. The hexane fraction also obtained from frond methanolic extract, showed a trichomonacidal effect with an IC50 of 82.8 μg/mL and a low cytotoxic effect. Hsf6 exhibited the highest activity against T. vaginalis, and the GC-MS analysis revealed that the predominant compound was 16-pregnenolone. The remaining identified compounds were primarily terpene-type compounds.

Therapeutic efficacy of a K5-specific phage and depolymerase against Klebsiella pneumoniae in a mouse model of infection

Klebsiella pneumoniae has become one of the most intractable gram-negative pathogens infecting humans and animals due to its severe antibiotic resistance. Bacteriophages and protein products derived from them are receiving increasing amounts of attention as potential alternatives to antibiotics. In this study, we isolated and investigated the characteristics of a new lytic phage, P1011, which lyses K5 K. pneumoniae specifically among 26 serotypes. The K5-specific capsular polysaccharide-degrading depolymerase dep1011 was identified and expressed. By establishing murine infection models using bovine strain B16 (capable of supporting phage proliferation) and human strain KP181 (incapable of sustaining phage expansion), we explored the safety and efficacy of phage and dep1011 treatments against K5 K. pneumoniae. Phage P1011 resulted in a 60% survival rate of the mice challenged with K. pneumoniae supporting phage multiplication, concurrently lowering the bacterial burden in their blood, liver, and lungs. Unexpectedly, even when confronted with bacteria impervious to phage multiplication, phage therapy markedly decreased the number of viable organisms. The protective efficacy of the depolymerase was significantly better than that of the phage. The depolymerase achieved 100% survival in both treatment groups regardless of phage propagation compatibility. These findings indicated that P1011 and dep1011 might be used as potential antibacterial agents to control K5 K. pneumoniae infection.

Superinfections of the Spine: A Single-Institution Experience

Background/Objectives: A superinfection occurs when a new, secondary organism colonizes an existing infection. Spine infections are associated with high patient morbidity and sometimes require multiple irrigations and debridements (I&Ds). When multiple I&Ds are required, the risk of complications increases. The purpose of this study was to report our experience with spine superinfections and determine which patients are typically affected. Methods: A retrospective case series of spine superinfections and a retrospective case-control analysis were conducted. Data were collected manually from electronic medical records. Spine I&Ds were identified. Groups were created for patients who had multiple I&Ds for (1) a recurrence of the same causative organism or (2) a superinfection with a novel organism. Preoperative demographic, clinical, and microbiologic data were compared between these two outcomes. A case series of superinfections with descriptive data was constructed. Lastly, two illustrative cases were provided in a narrative format. Results: A total of 92 patients were included in this analysis. Superinfections occurred after 6 out of the 92 (7%) initial I&Ds and were responsible for 6 out of the 24 (25%) repeat I&Ds. The preoperative erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) of the patients with a superinfection were significantly lower than those in the control group (p = 0.022 and p = 0.032). Otherwise, the observed differences in the preoperative variables were not statistically different. In the six cases of superinfection, the presence of high-risk comorbidities, a history of substance abuse, or a lack of social support were commonly observed. The superinfecting organisms included Candida, Pseudomonas, Serratia, Klebsiella, Enterobacter, and Staphylococcus species. Conclusions: Superinfections are a devastating complication requiring reoperation after initial spine I&D. Awareness of the possibility of superinfection and common patient archetypes can be helpful for clinicians and care teams. Future work is needed to examine how to identify, help predict, and prevent spine superinfections.

Photocatalytic degradation of antibiotics and antimicrobial and anticancer activities of two-dimensional ZnO nanosheets

Active pharmaceutical ingredients have emerged as an environmentally undesirable element because of their widespread exploitation and consequent pollution, which has deleterious effects on living things. In the pursuit of sustainable environmental remediation, biomedical applications, and energy production, there has been a significant focus on two-dimensional materials (2D materials) owing to their unique electrical, optical, and structural properties. Herein, we have synthesized 2D zinc oxide nanosheets (ZnO NSs) using a facile and practicable hydrothermal method and characterized them thoroughly using spectroscopic and microscopic techniques. The 2D nanosheets are used as an efficient photocatalyst for antibiotic (herein, end-user ciprofloxacin (CIP) was used as a model antibiotic) degradation under sunlight. It is observed that ZnO NSs photodegrade ~ 90% of CIP within two hours of sunlight illumination. The molecular mechanism of CIP degradation is proposed based on ex-situ IR analysis. Moreover, the 2D ZNO NSs are used as an antimicrobial agent and exhibit antibacterial qualities against a range of bacterial species, including Escherichia coli, Staphylococcus aureus, and MIC of the bacteria are found to be 5 μg/l and 10 μg/l, respectively. Despite having the biocompatible nature of ZnO, as-synthesized nanosheets have also shown cytotoxicity against two types of cancer cells, i.e. A549 and A375. Thus, ZnO nanosheets showed a nontoxic nature, which can be exploited as promising alternatives in different biomedical applications.

A novel chimeric vaccine containing multiple epitopes for simulating robust immune activation against Klebsiella pneumoniae

BACKGROUND

Due to antibiotic resistance, the Klebsiella genus is linked to morbidity and death, necessitating the development of a universally protective vaccine against Klebsiella pathogens.

METHODS

Core sequence analysis prioritized non-redundant host molecules and expected lipid bilayer peptides from fully sequenced Klebsiella genomes. These proteins were refined to identify epitopes, examining their immunogenicity, toxicity, solubility, and interaction with MHC alleles. Epitopes were linked to CPG ODN C274 via EAAAK, HEYGAEALERAG, and GGGS linkers to enhance immunological responses. The vaccine's tertiary structure was modelled and docked with MHC-I and MHC-II.

RESULTS

Fifty-five proteins were recognized in the Vaxign collection as having remarkable features. Twenty-three proteins with potential pathogenicity were then identified. Eight options for vaccines emerged after the immunogenicity of proteins was examined. The best antigens were three proteins: MrkD, Iron-regulated lipid membrane polypeptides, and RmpA. These compounds were selected for their sensitivity. The structural protein sequences of K. pneumoniae were utilized to identify seven CTL epitopes, seven HTL epitopes, and seven LBL epitopes, respectively. The produced immunization displayed a stable contact with the receptors, based on molecular dynamic simulations lasting 250 nanoseconds. Intermolecular binding free energies also indicated the dominance of the van der Waals and electrostatic energies.

CONCLUSION

In summary, the results of this study might help scientists develop a novel vaccine to prevent K. pneumoniae infections.

Active surveillance of antimicrobial resistance in companion animals: A pilot study in a Spanish Veterinary Teaching Hospital

The role of small animal veterinary hospitals in the onset and dissemination of antimicrobial-resistant organisms (AMROs) is still not clear, and the implementation of an internal surveillance systems is a cost-effective tool to better understand their impact. The aim of this study was to describe a pilot program of active surveillance in a Spanish Veterinary Teaching Hospital, developed to estimate the detection frequency of AMROs in the commensal flora of patients and in the environment. Surveillance was focused on Methicillin-resistant Staphylococci (MRS), third generation cephalosporins resistant gram-negative bacteria (3GCR-GNB), and carbapenems-resistant gram-negative bacteria (CR-GNB). Oral and perirectal swabs were collected in the same dogs and cats hospitalized > 48 h, at their admission and before their discharge. Out of 50 patients sampled, 24% (12/50) were carriers at admission of at least one of the three investigated AMROs. Twenty-eight percent of patients (14/50) acquired at least one AMRO during the hospital stay. MRS detection frequency at admission was 12% (6/50), while acquisition was 6% (3/50). 3GCR-GNB detection frequency was 14% at admission (7/50) and acquisition 22% (11/50), while CR-GNB detection frequency was 2% at admission (1/50) and acquisition 2% (1/50). Environmental surveillance (98 samples) showed a total detection frequency of 22.4% for MRS (22/98), 2% for 3GCR-GNB and CR-GNB (2/98). Clinical staff' shoe soles showed high detection frequency for MRS (50%). 3GCR Escherichia coli was the most isolated species in patients (n = 17). The results show how active surveillance can be used as a tool to assess the impact of AMROs in veterinary hospitals to subsequently build up tailored control plans based on specific issues.

Evaluating the Effect of pH, Temperature and Concentration on Antioxidant and Antibacterial Potential of Spectroscopically, Spectrophotometrically and Microscopically Characterized Mentha Spicata Capped Silver Nanoparticles

The use of traditional plants has been tremendously increased due to their higher biological impact, minimal side effects, and comparatively low cost. Moreover, the emergence of antibacterial resistance is also shifting the scientific community to reconsider herbal remedies which provide relatively safer, cheap and biologically tolerable solutions. The present research was designed to fabricate the Mentha spicata conjugated silver nanoparticles (Me-AgNPs). Furthermore, the assessment of the bactericidal potential of Me-AgNPs against various bacterial strains was another motive behind this study. Fabricated NPs were characterized with the help of the UV-Visible spectrophotometric analysis, Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). Me-AgNPs showed a significant zone of inhibition (23 ± 0.2 mm) at 8 mg/mL against Staphylococcus aureus and a 4.0 ± 0.2 mm zone of growth inhibition at 2 mg/mL against Aeromonas veronii. The stability of Me-AgNPs was assessed at various pH (4, 7 and 11) and temperatures (25 °C, 4 °C, 37 °C, 75 °C). The significant zones of inhibition (11.3 ± 0.3 mm, 8.3 ± 0.3mm, 14.3 ± 0.3 mm, and 7.6 ± 0.2 mm) were observed at pH 11 against Escherichia coli, Staphylococcus aureus, Bacillus subtilis, and Klebsiella pneumoniae, respectively. Growth inhibition zones (14.0 ± 0.5 mm and 13.0 ± 0.5 mm) were also determined against B. subtilis and S. aureus at 25 °C. DPPH bioassay was conducted to find the antioxidant properties of Me-AgNPs. The highest (38.66 ± 0.2%) free radical scavenging activity was shown by Me-AgNPs at 4 mg/mL. Present study results concluded that biogenic Me-AgNPs have bactericidal as well as anti-oxidative potential. Moreover, these green synthesized Me-AgNPs could maintain their potency and stability at a wide range of pH and temperature.

Toxicological assessment of photoactivated tetra-cationic porphyrin molecules under white light exposure in a Caenorhabditis elegans model

Photodynamic therapy (PDT) utilizes the potential of photosensitizing substances to absorb light energy and produce reactive oxygen species. Tetra-cationic porphyrins, which have organic or coordination compounds attached to their periphery, are heterocyclic derivatives with well-described antimicrobial and antitumoral properties. This is due to their ability to produce reactive oxygen species and their photobiological properties in solution. Consequently, these molecules are promising candidates as new and more effective photosensitizers with biomedical, environmental, and other biomedical applications. Prior to human exposure, it is essential to establish the toxicological profile of these molecules using in vivo models. In this study, we used Caenorhabditis elegans, a small free-living nematode, as a model for assessing toxic effects and predicting toxicity in preclinical research. We evaluated the toxic effects of porphyrins (neutral and tetra-cationic) on nematodes under dark/light conditions. Our findings demonstrate that tetra-methylated porphyrins (3TMeP and 4TMeP) at a concentration of 3.3 µg/mL (1.36 and 0.93 µM) exhibit high toxicity (as evidenced by reduced survival, development, and locomotion) under dark conditions. Moreover, photoactivated tetra-methylated porphyrins induce higher ROS levels compared to neutral (3TPyP and 4TPyP), tetra-palladated (3PdTPyP and 4PdTPyP), and tetra-platinated (3PtTPyP and 4PtTPyP) porphyrins, which may be responsible for the observed toxic effects.

Design, synthesis, and bioactivity evaluation of clindamycin derivatives against multidrug-resistant bacterial strains

Our research aims to reduce the bacterial resistance of clindamycin against Gram-positive bacteria and expand its range of bacterial susceptibility. First, we optimized the structure of clindamycin based on its structure-activity relationship. Second, we employed the fractional inhibitory concentration method to detect drugs suitable for combination with clindamycin derivatives. We then used a linker to connect the clindamycin derivatives with the identified combined therapy drugs. Finally, we tested antibacterial susceptibility testing and conducted in vitro bacterial inhibition activity assays to determine the compounds. with the highest efficacy. The results of our study show that we synthesized clindamycin propionate derivatives and clindamycin homo/heterodimer derivatives, which exhibited superior antibacterial activity compared to clindamycin and other antibiotics against both bacteria and fungi. In vitro bacteriostatic activity testing against four types of Gram-negative bacteria and one type of fungi revealed that all synthesized compounds had bacteriostatic effects at least 1000 times better than clindamycin and sulfonamides. The minimum inhibitory concentration (MIC) values for these compounds ranged from 0.25 to 0.0325 mM. Significantly, compound 5a demonstrated the most potent inhibitory activity against three distinct bacterial strains, displaying MIC values spanning from 0.0625 to 0.0325 mM. Furthermore, our calculations indicate that compound 5a is safe for cellular use. In conclusion, the synthesized compounds hold great promise in addressing bacterial antibiotic resistance.

Lipophilic bioactive compounds from thermophilic cyanobacterium Leptolyngbya sp. HNBGU-004: Implications for countering VRSA resistance

Extremophiles thrive in extreme conditions, showcasing rich and unexplored diversity. This resilience hints at the existence of novel biochemical pathways and unique bioactive compounds. In contrast, the issue of drug resistance and excessive misuse of antibiotics in various settings, such as healthcare, agriculture, and veterinary medicine, has contributed to the emergence and spread of drug-resistant microorganisms. In the present research, Leptolyngbya sp. HNBGU-004, was obtained from an extreme location, a hot water spring in the Garhwal Himalayan region of India. The lipophilic fraction derived from Leptolyngbya sp. HNBGU-004 exhibited significant inhibitory effects against vancomycin-resistant Staphylococcus aureus (VRSA), displaying a bactericidal concentration of 0.5 mg mL-1. Furthermore, gas chromatography-mass spectrometry (GC-MS) analysis of the lipophilic extract unveiled the major constituents. Leptolyngbya sp. HNBGU-004 holds significant promise as a primary source of potent anti-vancomycin-resistant S. aureus components. These findings emphasize the importance of Leptolyngbya sp. HNBGU-004 as a foundational source for use as both a synergistic and alternative agent against VRSA.

Efficacy and safety of antibiotics targeting Gram-negative bacteria in nosocomial pneumonia: a systematic review and Bayesian network meta-analysis

BACKGROUND

Multiple randomized controlled studies have compared numerous antibiotic regimens, including new, recently commercialized antibiotics in the treatment of nosocomial pneumonia (NP). The objective of this Bayesian network meta-analysis (NMA) was to compare the efficacy and the safety of different antibiotic treatments for NP.

METHODS

We conducted a systematic search of PubMed, Medline, Web of Science, EMBASE and the Cochrane Library databases from 2000 through 2021. The study selection included studies comparing antibiotics targeting Gram-negative bacilli in the setting of NP. The primary endpoint was 28 day mortality. Secondary outcomes were clinical cure, microbiological cure and adverse events.

RESULTS

Sixteen studies encompassing 4993 patients were included in this analysis comparing 13 antibiotic regimens. The level of evidence for mortality comparisons ranged from very low to moderate. No significant difference in 28 day mortality was found among all beta-lactam regimens. Only the combination of meropenem plus aerosolized colistin was associated with a significant decrease of mortality compared to using intravenous colistin alone (OR = 0.43; 95% credible interval [0.17-0.94]), based on the results of the smallest trial included. The clinical failure rate of ceftazidime was higher than meropenem with (OR = 1.97; 95% CrI [1.19-3.45]) or without aerosolized colistin (OR = 1.40; 95% CrI [1.00-2.01]), imipemen/cilastatin/relebactam (OR = 1.74; 95% CrI [1.03-2.90]) and ceftazidime/avibactam (OR = 1.48; 95% CrI [1.02-2.20]). For microbiological cure, no substantial difference between regimens was found, but ceftolozane/tazobactam had the highest probability of being superior to comparators. In safety analyses, there was no significant difference between treatments for the occurrence of adverse events, but acute kidney failure was more common in patients receiving intravenous colistin.

CONCLUSIONS

This network meta-analysis suggests that most antibiotic regimens, including new combinations and cefiderocol, have similar efficacy and safety in treating susceptible Gram-negative bacilli in NP. Further studies are necessary for NP caused by multidrug-resistant bacteria. Registration PROSPERO CRD42021226603.

Polydispersity-mediated high efficacy of an in-situ aqueous nanosuspension of PPEF.3HCl in methicillin resistant Staphylococcus aureus sepsis model

Recently, World Health Organization declared antimicrobial resistance as the third greatest threat to human health. Absence of known cross-resistance, new class, new target, and a new mode of action are few major strategies being undertaken by researches to combat multidrug resistant pathogen. PPEF.3HCl, a bisbenzimidazole was developed as highly potent antibacterial agent against ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) pathogens, targeting topoisomerase IA. The present work encompasses a radical on-site generation of In-situ nanosuspension of PPEF.3HCl with enhanced efficacy against methicillin resistant S. aureus in septicemia model. We have generated instantaneously a PPEF.3HCl nanosuspension (IsPPEF.3HCl-NS) by mixing optimized monophasic PPEF.3HCl preconcentrate in propylene glycol into an aqueous medium comprising tween 80 as stabilizer. The IsPPEF.3HCl-NS showed precipitation efficiency of > 90 %, average particle size < 500 nm, retained upto 5 h, a negative zeta potential and bi/trimodal particle size distribution. Differential scanning calorimetry, X-ray diffraction confirmed partial amorphization and transmission electron microscopy revealed spherical particles. IsPPEF.3HCl-NS was non-hemolytic and exhibited good stability in serum. More significantly, it exhibited a ∼ 1.6-fold increase in macrophage uptake compared to free PPEF.3HCl in the RAW 264.7 macrophage cell line. Confocal microscopy revealed accumulation of IsPPEF.3HCl-NS within the lysosomal compartment and cell cytosol, proposing high efficacy. In terms of antimicrobial efficacy, IsPPEF.3HCl-NS outperforms free PPEF.3HCl against clinical methicillin sensitive and resistant S. aureus strains. In a pivotal experiment, IsPPEF.3HCl-NS exhibited over 83 % survival at 8 mg/kg.bw and an impressive reduction of ∼ 4-5 log-fold in bacterial load, primarily in the kidney, liver and spleen of septicemia mice. IsPPEF.3HCl-NS prepared by the In-situ approach, coupled with enhanced intramacrophage delivery and superior efficacy, positions IsPPEF.3HCl-NS as a pioneering and highly promising formulation in the battle against antimicrobial resistance.

Seriphidium herba-alba (Asso): A comprehensive study of essential oils, extracts, and their antimicrobial properties

Seriphidium herba-alba (Asso), a plant celebrated for its therapeutic qualities, is widely used in traditional medicinal practices throughout the Middle East and North Africa. In a detailed study of Seriphidium herba-alba (Asso), essential oils and extracts were analyzed for their chemical composition and antimicrobial properties. The essential oil, characterized using mass spectrometry and retention index methods, revealed a complex blend of 52 compounds, with santolina alcohol, α-thujone, β-thujone, and chrysanthenone as major constituents. Extraction yields varied significantly, depending on the plant part and method used; notably, methanol soaking of aerial parts yielded the most extract at 17.75%. The antimicrobial analysis showed that the extracts had selective antibacterial activity, particularly against Staphylococcus aureus, and broad-spectrum antifungal activity against organisms such as Candida albicans and Aspergillus spp. The methanol-soaked extract demonstrated the strongest antimicrobial properties, indicating its potential as a natural antimicrobial source. This study not only underscores the therapeutic potential of Seriphidium herba-alba (Asso) in pharmaceutical applications but also sets a foundation for future research focused on isolating specific bioactive compounds and in vivo testing.

Potential Anti-Infectious Activity of Essential Oil Chemotypes of Lippia origanoides Kunth on Antibiotic-Resistant Staphylococcus aureus Strains

Staphylococcus aureus infections are prevalent in healthcare and community environments. Methicillin-resistant S. aureus is catalogued as a superbug of high priority among the pathogens. This Gram-positive coccus can form biofilms and produce toxins, leading to persistent infection and antibiotic resistance. Limited effective antibiotics have encouraged the development of innovative strategies, with a particular emphasis on resistance mechanisms and/or virulence factors. Medicinal aromatic plants have emerged as promising alternative sources. This study investigated the antimicrobial, antibiofilm, and antihemolysis properties of three different chemotypes of Lippia origanoides essential oil (EO) against susceptible and drug-resistant S. aureus strains. The chemical composition of the EO was analyzed using GC-MS, revealing high monoterpene concentrations, with carvacrol and thymol as the major components in two of the chemotypes. The third chemotype consisted mainly of the sesquiterpene β-caryophyllene. The MIC values for the two monoterpene chemotypes ranged from 62.5 to 500 µg/mL for all strains, whereas the sesquiterpene chemotype showed activity against seven strains at concentrations of 125-500 µg/mL, which is the first report of its anti-S. aureus activity. The phenolic chemotypes inhibited biofilm formation in seven S. aureus strains, whereas the sesquiterpene chemotype only inhibited biofilm formation in four strains. In addition, phenolic chemotypes displayed antihemolysis activity, with IC50 values ranging from 58.9 ± 3.8 to 128.3 ± 9.2 µg/mL. Our study highlights the importance of L. origanoides EO from the Yucatan Peninsula, which has the potential for the development of anti-S. aureus agents.

Heavy Metals as Catalysts in the Evolution of Antimicrobial Resistance and the Mechanisms Underpinning Co-selection

The menace caused by antibiotic resistance in bacteria is acknowledged on a global scale. Concerns over the same are increasing because of the selection pressure exerted by a huge number of different antimicrobial agents, including heavy metals. Heavy metals are non-metabolizable and recalcitrant to degradation, therefore the bacteria can expel the pollutants out of the system and make it less harmful via different mechanisms. The selection of antibiotic-resistant bacteria may be influenced by heavy metals present in environmental reservoirs. Through co-resistance and cross-resistance processes, the presence of heavy metals in the environment can act as co-selecting agents, hence increasing resistance to both heavy metals and antibiotics. The horizontal gene transfer or mutation assists in the selection of mutant bacteria resistant to the polluted environment. Hence, bioremediation and biodegradation are sustainable methods for the natural clean-up of pollutants. This review sheds light on the occurrence of metal and antibiotic resistance in the environment via the co-resistance and cross-resistance mechanisms underpinning co-selection emphasizing the dearth of studies that specifically examine the method of co-selection in clinical settings. Furthermore, it is advised that future research incorporate both culture- and molecular-based methodologies to further our comprehension of the mechanisms underlying bacterial co- and cross-resistance to antibiotics and heavy metals.

Applications of peptides in nanosystems for diagnosing and managing bacterial sepsis

Sepsis represents a critical medical condition stemming from an imbalanced host immune response to infections, which is linked to a significant burden of disease. Despite substantial efforts in laboratory and clinical research, sepsis remains a prominent contributor to mortality worldwide. Nanotechnology presents innovative opportunities for the advancement of sepsis diagnosis and treatment. Due to their unique properties, including diversity, ease of synthesis, biocompatibility, high specificity, and excellent pharmacological efficacy, peptides hold great potential as part of nanotechnology approaches against sepsis. Herein, we present a comprehensive and up-to-date review of the applications of peptides in nanosystems for combating sepsis, with the potential to expedite diagnosis and enhance management outcomes. Firstly, sepsis pathophysiology, antisepsis drug targets, current modalities in management and diagnosis with their limitations, and the potential of peptides to advance the diagnosis and management of sepsis have been adequately addressed. The applications have been organized into diagnostic or managing applications, with the last one being further sub-organized into nano-delivered bioactive peptides with antimicrobial or anti-inflammatory activity, peptides as targeting moieties on the surface of nanosystems against sepsis, and peptides as nanocarriers for antisepsis agents. The studies have been grouped thematically and discussed, emphasizing the constructed nanosystem, physicochemical properties, and peptide-imparted enhancement in diagnostic and therapeutic efficacy. The strengths, limitations, and research gaps in each section have been elaborated. Finally, current challenges and potential future paths to enhance the use of peptides in nanosystems for combating sepsis have been deliberately spotlighted. This review reaffirms peptides' potential as promising biomaterials within nanotechnology strategies aimed at improving sepsis diagnosis and management.

Development of CuO Nanoparticles from the Mucus of Garden Snail Cornu aspersum as New Antimicrobial Agents

Several biologically active compounds involved in the green synthesis of silver and gold nanoparticles have been isolated from snail mucus and characterized. This paper presents a successful method for the application of snail mucus from Cornu aspersum as a bioreducing agent of copper sulfate and as a biostabilizer of the copper oxide nanoparticles (CuONPs-Muc) obtained. The synthesis at room temperature and neutral pH yielded nanoparticles with a spherical shape and an average diameter of 150 nm. The structure and properties of CuONPs-Muc were characterized using various methods and techniques, such as ultraviolet-visible spectroscopy (UV-vis), high-performance liquid chromatography (HPLC), one-dimensional polyacrylamide gel electrophoresis (1D-PAGE), up-conversion infrared spectroscopy Fourier transform (FTIR), scanning electron microscopy combined with energy dispersive spectroscopy (SEM/EDS), Raman spectroscopy and imaging, thermogravimetric analysis (TG-DSC), etc. Mucus proteins with molecular weights of 30.691 kDa and 26.549 kDa were identified, which are involved in the biogenic production of CuONPs-Muc. The macromolecular shell of proteins formed around the copper ions contributes to a higher efficiency of the synthesized CuONPs-Muc in inhibiting the bacterial growth of several Gram-positive (Bacillus subtilis NBIMCC2353, Bacillus spizizenii ATCC 6633, Staphylococcus aureus ATCC 6538, Listeria innocua NBIMCC8755) and Gram-negative (Escherichia coli ATCC8739, Salmonella enteitidis NBIMCC8691, Salmonella typhimurium ATCC 14028, Stenotrophomonas maltophilia ATCC 17666) bacteria compared to baseline mucus. The bioorganic synthesis of snail mucus presented here provides CuONPs-Muc with a highly pronounced antimicrobial effect. These results will expand knowledge in the field of natural nanomaterials and their role in emerging dosage forms.

Restricted Rotational Flexibility of the C5α-Methyl-Substituted Carbapenem NA-1-157 Leads to Potent Inhibition of the GES-5 Carbapenemase

Carbapenem antibiotics are used as a last-resort treatment for infections caused by multidrug-resistant bacteria. The wide spread of carbapenemases in Gram-negative bacteria has severely compromised the utility of these drugs and represents a serious public health threat. To combat carbapenemase-mediated resistance, new antimicrobials and inhibitors of these enzymes are urgently needed. Here, we describe the interaction of the atypically C5α-methyl-substituted carbapenem, NA-1-157, with the GES-5 carbapenemase. MICs of this compound against Escherichia coli, Klebsiella pneumoniae, and Acinetobacter baumannii producing the enzyme were reduced 4-16-fold when compared to MICs of the commercial carbapenems, reaching clinically sensitive breakpoints. When NA-1-157 was combined with meropenem, a strong synergistic effect was observed. Kinetic and ESI-LC/MS studies demonstrated that NA-1-157 is a potent inhibitor of GES-5, with a high inactivation efficiency of (2.9 ± 0.9) × 105 M-1 s-1. Acylation of GES-5 by NA-1-157 was biphasic, with the fast phase completing within seconds, and the slow phase taking several hours and likely proceeding through a reversible tetrahedral intermediate. Deacylation was extremely slow (k3 = (2.4 ± 0.3) × 10-7 s-1), resulting in a residence time of 48 ± 6 days. MD simulation of the GES-5-meropenem and GES-5-NA-1-157 acyl-enzyme complexes revealed that the C5α-methyl group in NA-1-157 sterically restricts rotation of the 6α-hydroxyethyl group preventing ingress of the deacylating water into the vicinity of the scissile bond of the acyl-enzyme intermediate. These data demonstrate that NA-1-157 is a potent irreversible inhibitor of the GES-5 carbapenemase.

Monoclonal antibodies derived from B cells in subjects with cystic fibrosis reduce Pseudomonas aeruginosa burden in mice

Pseudomonas aeruginosa (PA) is an opportunistic, frequently multidrug-resistant pathogen that can cause severe infections in hospitalized patients. Antibodies against the PA virulence factor, PcrV, protect from death and disease in a variety of animal models. However, clinical trials of PcrV-binding antibody-based products have thus far failed to demonstrate benefit. Prior candidates were derivations of antibodies identified using protein-immunized animal systems and required extensive engineering to optimize binding and/or reduce immunogenicity. Of note, PA infections are common in people with cystic fibrosis (pwCF), who are generally believed to mount normal adaptive immune responses. Here we utilized a tetramer reagent to detect and isolate PcrV-specific B cells in pwCF and, via single-cell sorting and paired-chain sequencing, identified the B cell receptor (BCR) variable region sequences that confer PcrV-specificity. We derived multiple high affinity anti-PcrV monoclonal antibodies (mAbs) from PcrV-specific B cells across 3 donors, including mAbs that exhibit potent anti-PA activity in a murine pneumonia model. This robust strategy for mAb discovery expands what is known about PA-specific B cells in pwCF and yields novel mAbs with potential for future clinical use.

A Study of the Synergistic Effects of Essential Oils from Origanum compactum and Origanum elongatum with Commercial Antibiotics against Highly Prioritized Multidrug-Resistant Bacteria for the World Health Organization

The irrational use of antibiotics has favored the emergence of resistant bacteria, posing a serious threat to global health. To counteract antibiotic resistance, this research seeks to identify novel antimicrobials derived from essential oils that operate through several mechanisms. It aims to evaluate the quality and composition of essential oils from Origanum compactum and Origanum elongatum; test their antimicrobial activity against various strains; explore their synergies with commercial antibiotics; predict the efficacy, toxicity, and stability of compounds; and understand their molecular interactions through docking and dynamic simulations. The essential oils were extracted via hydrodistillation from the flowering tops of oregano in the Middle Atlas Mountains in Morocco. Gas chromatography combined with mass spectrometry (GC-MS) was used to examine their composition. Nine common antibiotics were chosen and tested alone or in combination with essential oils to discover synergistic effects against clinically important and resistant bacterial strains. A comprehensive in silico study was conducted, involving molecular docking and molecular dynamics simulations (MD). O. elongatum oil includes borneol (8.58%), p-cymene (42.56%), thymol (28.43%), and carvacrol (30.89%), whereas O. compactum oil is mostly composed of γ-terpinene (22.89%), p-cymene (15.84%), thymol (10.21%), and (E)-caryophyllene (3.63%). With O. compactum proving to be the most potent, these essential oils showed antibacterial action against both Gram-positive and Gram-negative bacteria. Certain antibiotics, including ciprofloxacin, ceftriaxone, amoxicillin, and ampicillin, have been shown to elicit synergistic effects. To fight resistant bacteria, the essential oils of O. compactum and O. elongatum, particularly those high in thymol and (E)-caryophyllene, seem promising when combined with antibiotics. These synergistic effects could result from their ability to target the same bacterial proteins or facilitate access to target sites, as suggested by molecular docking simulations. Molecular dynamics simulations validated the stability of the examined protein-ligand complexes, emphasizing the propensity of substances like thymol and (E)-caryophyllene for particular target proteins, opening the door to potentially effective new therapeutic approaches against pathogens resistant to multiple drugs.