Antimicrobial resistance: a global multifaceted phenomenon

Extended spectrum beta-lactamase carriage among elderly residents of a long-term care facility in Beirut

BACKGROUND

Antimicrobial resistance is an emerging problem worldwide, endangering antimicrobials efficacy and resulting in high rates of morbidity and mortality. It is one of the major concerns that health care facilities are facing nowadays. Mainly, extended-spectrum beta-lactamases (ESBL)-producing Enterobacterales play a role in hydrolyzing β-lactams, specifically the third-generation cephalosporins. This study aimed to investigate the prevalence of fecal carriage and molecular characterization of ESBL-producing Enterobacterales among Lebanese elderly residents in a long-term care facility (Dar Al-Ajaza Al Islamia Hospital).

METHODS

Rectal culture swab specimens were collected from 132 patients at Dar Al Ajaza Al Islamia hospital between January 2019 till June 2020. The phenotype of ESBL producers was confirmed by a modified double disc synergy test and antibiotic susceptibility was determined using the Kirby-Bauer disk diffusion method. Genotypically, multiplex polymerase chain reaction was used to detect the ESBL genes.

RESULTS

The main Enterobacterales strain observed was E coli (90.15%) followed by Klebsiella pneumoniae (4.54%) and Klebsiella oxytoca (3.80%). It has been found that the ESBL percentage rate has decreased when compared to a study conducted previously at the same hospital. Moreover, the predominant ESBL gene was CTX-M (cefotaximase).

CONCLUSIONS

This study is the first to demonstrate the improved current status of ESBL in one long-term care facility. In addition, the CTX-M is still the major type in ESBL-producing organisms.

Rapid testing of antibiotic residues to increase food safety awareness of animal origin

Background and Aim

Antibiotics are used to improve growth, reduce disease, and decrease mortality in animals grown for food. The government regulates and prohibits the use of antibiotics, in particular, the use of antibiotic growth promoter (AGP) in livestock; however, it is not yet known whether the use of antibiotics is in accordance with regulations so that there are no antibiotic residues in food of animal origin. To ensure food safety of animal origin and to raise awareness of food safety, it is necessary to detect antibiotic residues in fish, eggs, and chicken meat from Yogyakarta Special Province through monitoring and monitoring. To ensure food safety and regulatory compliance in food samples, antibiotic residue screening techniques are essential. A number of methods, such as time-consuming and costly chromatographic and spectroscopic methods, have been developed for the detection of antibiotic residues in food samples; however, not all laboratories have these facilities. Therefore, a rapid diagnosis of food of animal origin is required. The purpose of this study was to rapidly test antibiotic residues by using Premi®test kits (R-Biopharm AG, Germany) to increase awareness of food safety of animal origin.

Materials and Methods

We tested 345 animal-based food samples from traditional markets, supermarkets, and central markets in five districts of Yogyakarta Special Province for antibiotic residues using rapid test kits and observation questionnaires to identify risk factors.

Results

The presence of antibiotic residues in food-animal origin samples from the Yogyakarta region had an antibiotic residue level of 9.28% (32/345), consisting of fish samples 11.3% (18/97), eggs 15.65% (1/114), and chicken meat samples 0.87% (13/102). The highest percentage of samples positive for residual antibiotics was 21.9% (7/32) from supermarket meat samples. The highest amounts of antibiotic residues were found in fish samples collected from Sleman Regency, up to 25% (8/32), whereas in supermarket fish samples, there were as high as 18.8% (6/32).

Conclusion

Antibiotic residues in animal-based food can be attributed to various factors, including product source, transportation conditions, and environmental conditions. The widespread distribution of antibiotic residues in fish comes from environmental conditions during maintenance, distribution, and retailing. Monitoring antibiotic residue prevalence in food-animal origins, particularly chicken meat, eggs, and fish, is crucial for improving animal food quality and safety.

Emerging strategies and therapeutic innovations for combating drug resistance in Staphylococcus aureus strains: A comprehensive review

In recent years, antibiotic therapy has encountered significant challenges due to the rapid emergence of multidrug resistance among bacteria responsible for life-threatening illnesses, creating uncertainty about the future management of infectious diseases. The escalation of antimicrobial resistance in the post-COVID era compared to the pre-COVID era has raised global concern. The prevalence of nosocomial-related infections, especially outbreaks of drug-resistant strains of Staphylococcus aureus, have been reported worldwide, with India being a notable hotspot for such occurrences. Various virulence factors and mutations characterize nosocomial infections involving S. aureus. The lack of proper alternative treatments leading to increased drug resistance emphasizes the need to investigate and examine recent research to combat future pandemics. In the current genomics era, the application of advanced technologies such as next-generation sequencing (NGS), machine learning (ML), and quantum computing (QC) for genomic analysis and resistance prediction has significantly increased the pace of diagnosing drug-resistant pathogens and insights into genetic intricacies. Despite prompt diagnosis, the elimination of drug-resistant infections remains unattainable in the absence of effective alternative therapies. Researchers are exploring various alternative therapeutic approaches, including phage therapy, antimicrobial peptides, photodynamic therapy, vaccines, host-directed therapies, and more. The proposed review mainly focuses on the resistance journey of S. aureus over the past decade, detailing its resistance mechanisms, prevalence in the subcontinent, innovations in rapid diagnosis of the drug-resistant strains, including the applicants of NGS and ML application along with QC, it helps to design alternative novel therapeutics approaches against S. aureus infection.

System-wide approaches to antimicrobial therapy and antimicrobial resistance in the UK: the AMR-X framework

Antimicrobial resistance (AMR) threatens human, animal, and environmental health. Acknowledging the urgency of addressing AMR, an opportunity exists to extend AMR action-focused research beyond the confines of an isolated biomedical paradigm. An AMR learning system, AMR-X, envisions a national network of health systems creating and applying optimal use of antimicrobials on the basis of their data collected from the delivery of routine clinical care. AMR-X integrates traditional AMR discovery, experimental research, and applied research with continuous analysis of pathogens, antimicrobial uses, and clinical outcomes that are routinely disseminated to practitioners, policy makers, patients, and the public to drive changes in practice and outcomes. AMR-X uses connected data-to-action systems to underpin an evaluation framework embedded in routine care, continuously driving implementation of improvements in patient and population health, targeting investment, and incentivising innovation. All stakeholders co-create AMR-X, protecting the public from AMR by adapting to continuously evolving AMR threats and generating the information needed for precision patient and population care.

Epidemiology of bacterial resistance at the Grand Magal of Touba in Senegal

BACKGROUND

The Grand Magal of Touba (GMT) associates with risks of infection, but no study on the circulation of resistant bacteria has yet been conducted.

MATERIALS AND METHODS

qPCR was performed on rectal samples from GMT pilgrims between 2018 and 2021, before and after their participation in the gathering. Rectal samples from between 2018 and 2020 were also cultured on specific media, and antibiotic susceptibility testing was performed.

RESULTS

Forty-one of the 296 (13.8%) pilgrims had at least one gastrointestinal symptom and 91/290 (31.4%) acquired pathogenic bacteria, mostly Escherichia coli. A total of 54.7% of pilgrims reported washing their hands more frequently than usual and 89.2% used soap. One hundred and five (36.2%) acquired at least one resistance gene, notably CTX-M A (21.0%), SHV (16.5%) and TEM (8.2%). The strains isolated by culture were mostly E. coli. These bacteria were found to be sensitive to carbapenems and resistant to amoxicillin and amoxicillin-clavulanic acid. The acquisition of enteroaggregative E. coli was independently associated with CTX-M A and TEM acquisition.

CONCLUSION

Pilgrims presented a risk for acquisition of CTX-M A after the GMT. Surveillance of the prevalence of resistant bacteria and the occurrence of associated clinical infections among pilgrims are necessary in the future.

Explaining the barriers faced by veterinarians against preventing antimicrobial resistance: an innovative interdisciplinary qualitative study

BACKGROUND

Considering the significance of increased antimicrobial resistance (AMR) and its adverse effects on individual and social health and the important and effective role that veterinarians play in controlling this growing issue worldwide, it is essential to have effective preventive control programs. To this aim, the first step is to identify the factors behind the prevalence of AMR in Iran and the barriers veterinarians face to controlling this problem. Thus, the present study was conducted to explain the barriers veterinarians faced in the prevention of AMR from an Iranian veterinarian's perspective.

METHODS

The present research was done in three cities in Iran in 2021. The data were collected through in-depth interviews with 18 veterinarians selected through purposive and snowball sampling and analyzed using conventional qualitative content analysis.

RESULTS

The data analysis results were classified into 4 main categories and 44 subcategories. The former included: educational factors, administrative/legal factors, client-related factors, and veterinarian-related factors.

CONCLUSIONS

The increased AMR can be approached from multiple aspects. Considering the different factors that affect the increased AMR, it is necessary to consider them all through effective planning and policy-making at multi-level and multidisciplinary dimensions. There is special attention needed to scientific and practical interventions at the individual, interpersonal, social, and even political levels. At the same time, measures should be taken to rehabilitate and maintain the health of society to strengthen supervision and attract the full participation of interested organizations.

A sustainable approach to prepare green synthesis of copper nanoparticles of Bauhinia variegata & Saussurea lappa: Unveiling in-vitro anti-obesity applications

Nanoparticles have different shapes and sizes between the range of 1-100 nm, which show advantages for stabilizing compounds, higher carrier capacity, and lower costs. Metal nanoparticles such as copper, gold, silver, and zinc are favorable components for various applications due to their interesting properties. In the present study, nanoparticles were synthesized by reduction with flower extracts of Bauhinia variegate & Saussurea lappa that were used to stabilize the copper nanoparticles. Furthermore, the characterization of plants synthesized copper nanoparticles was carried out through UV-visible dynamic light scattering. Additionally, morphological characterization of nanoparticles was confirmed by scanning electron microscopy and energy dispersive X-ray spectroscopy confirmed the elemental composition of copper nanoparticles. Powder X-ray diffraction was conducted for the analysis of crystallinity, purity, and crystal size of plant-synthesized copper nanoparticles. The average particle size was evaluated and exhibited the particle size at the peak of 8.721 nm and 98.03 nm for flower extracts of Bauhinia variegate & Saussurea lappa copper nanoparticles. The Fourier Transform Infrared spectrum was taken to scrutinize the various functional groups that were responsible for the reduction of the copper ions. The antimicrobial results against the bacterial strains with the positive test results of the zone of inhibition were for Bauhinia variegate (17 mm, 18 mm, 19 mm, and 18 mm) and Saussurea lappa (17 mm, 19 mm, 18 mm, and 18 mm) respectively for plants synthesized copper nanoparticles against the Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia and Pseudomonas aeruginosa. Lipase inhibition assay and Amylase inhibition assay with different concentrations (20 μg/mL to 100 μg/mL) for Bauhinia variegate & Saussurea lappa (12.34 %-59.67 % and 10.50 %-47.01 %) and (34.52 %-89.02 % and 22.34 %-56.45 %) confirmed the anti-obesity and anti-diabetic activities of plants extract synthesized copper nanoparticles.

One World, One Health: Zoonotic Diseases, Parasitic Diseases, and Infectious Diseases

When we take into account how the boundaries between human, animal, and environmental health are inextricably linked and increasingly intertwined, it comes as no surprise that the One Health approach has assumed an unprecedented level of importance over the past decade [...].

SAMP: Identifying Antimicrobial Peptides by an Ensemble Learning Model Based on Proportionalized Split Amino Acid Composition

It is projected that 10 million deaths could be attributed to drug-resistant bacteria infections in 2050. To address this concern, identifying new-generation antibiotics is an effective way. Antimicrobial peptides (AMPs), a class of innate immune effectors, have received significant attention for their capacity to eliminate drug-resistant pathogens, including viruses, bacteria, and fungi. Recent years have witnessed widespread applications of computational methods especially machine learning (ML) and deep learning (DL) for discovering AMPs. However, existing methods only use features including compositional, physiochemical, and structural properties of peptides, which cannot fully capture sequence information from AMPs. Here, we present SAMP, an ensemble random projection (RP) based computational model that leverages a new type of features called Proportionalized Split Amino Acid Composition (PSAAC) in addition to conventional sequence-based features for AMP prediction. With this new feature set, SAMP captures the residue patterns like sorting signals at around both the N-terminus and the C-terminus, while also retaining the sequence order information from the middle peptide fragments. Benchmarking tests on different balanced and imbalanced datasets demonstrate that SAMP consistently outperforms existing state-of-the-art methods, such as iAMPpred and AMPScanner V2, in terms of accuracy, MCC, G-measure and F1-score. In addition, by leveraging an ensemble RP architecture, SAMP is scalable to processing large-scale AMP identification with further performance improvement, compared to those models without RP. To facilitate the use of SAMP, we have developed a Python package freely available at https://github.com/wan-mlab/SAMP .

Design, Synthesis, and Biological Evaluation of Novel Arylomycins against Multidrug-Resistant Gram-Negative Bacteria

G0775, an arylomycin-type SPase I inhibitor that is being evaluated in a preclinical study, exhibited potent antibacterial activities against some Gram-negative bacteria but meanwhile suffered defects such as a narrow antibacterial spectrum and poor pharmacokinetic properties. Herein, systematic structural modifications were carried out, including optimization of the macrocyclic skeleton, warheads, and lipophilic regions. The optimization culminated in the discovery of 138f, which showed more potent activity and a broader spectrum against clinically isolated carbapenem-resistant Gram-negative bacteria, especially against Acinetobacter baumannii and Pseudomonas aeruginosa. 162, the free amine of 138f, exhibited an excellent pharmacokinetic profile in rats. In a neutropenic mouse thigh model of infection with multidrug-resistant P. aeruginosa, the potent in vivo antibacterial efficacy of 162 was confirmed and superior to that of G0775 (3.5-log decrease vs 1.1-log decrease in colony-forming unit (CFU)). These results support 162 as a potential antimicrobial agent for further research.

Rapid diagnosis of bloodstream infections using a culture-free phenotypic platform

BACKGROUND

Bloodstream infections (BSIs) are a life-threatening acute medical condition and current diagnostics for BSIs suffer from long turnaround time (TAT). Here we show the validation of a rapid detection-analysis platform (RDAP) for the diagnosis of BSIs performed on clinical blood samples METHODS: The validation was performed on a cohort of 59 clinical blood samples, including positive culture samples, which indicated confirmed bloodstream infections, and negative culture samples. The bacteria in the positive culture samples included Gram-positive and Gram-negative pathogenic species. RDAP is based on an electrochemical sandwich immunoassay with voltage-controlled signal amplification, which provides an ultra-low limit of detection (4 CFU/mL), allowing the platform to detect and identify bacteria without requiring culture and perform phenotypic antibiotic susceptibility testing (AST) with only 1-2 h of antibiotic exposure. The preliminary diagnostic performance of RDAP was compared with that of standard commercial diagnostic technologies.

RESULTS

Using a typical clinical microbiology laboratory diagnostic workflow that involved sample culture, agar plating, bacteria identification using matrix-assisted laser desorption ionization time-of-flight (MALDI TOF) mass spectrometry, and AST using MicroScan as a clinical diagnostic reference, RDAP showed diagnostic accuracy of 93.3% and 95.4% for detection-identification and AST, respectively. However, RDAP provided results at least 15 h faster.

CONCLUSIONS

This study shows the preliminary feasibility of using RDAP to rapidly diagnose BSIs, including AST. Limitations and potential mitigation strategies for clinical translation of the present RDAP prototype are discussed. The results of this clinical feasibility study indicate an approach to provide near real-time diagnostic information for clinicians to significantly enhance the treatment outcome of BSIs.

Synthesis, DFT Calculations, In Silico Studies, and Antimicrobial Evaluation of Benzimidazole-Thiadiazole Derivatives

In this study, a series of new benzimidazole-thiadiazole hybrids were synthesized, and the synthesized compounds were screened for their antimicrobial activities against eight species of pathogenic bacteria and three fungal species. Azithromycin, voriconazole, and fluconazole were used as reference drugs in the mtt assay. Among them, compounds 5f and 5h showed potent antifungal activity against C. albicans with a MIC of 3.90 μg/mL. Further, the results of the antimicrobial assay for compounds 5a, 5b, 5f, and 5h proved to be potent against E. faecalis (ATCC 2942) on the basis of an acceptable MIC value of 3.90 μg/mL. The cytotoxic effects of compounds that are effective as a result of their antimicrobial activity on healthy mouse fibroblast cells (L929) were evaluated. According to HOMO-LUMO analysis, compound 5h (with the lower ΔE = 3.417 eV) is chemically more reactive than the other molecules, which is compatible with the highest antibacterial and antifungal activity results. A molecular docking study was performed to understand their binding modes within the sterol 14-α demethylase active site and to interpret their promising fungal inhibitory activities. Molecular dynamics (MD) simulations of the most potent compounds 5f and 5h were found to be quite stable in the active site of the 14-α demethylase (5TZ1) protein.

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.

Investigating antimicrobial resistance genes in Kenya, Uganda and Tanzania cattle using metagenomics

Antimicrobial resistance (AMR) is a growing problem in African cattle production systems, posing a threat to human and animal health and the associated economic value chain. However, there is a poor understanding of the resistomes in small-holder cattle breeds in East African countries. This study aims to examine the distribution of antimicrobial resistance genes (ARGs) in Kenya, Tanzania, and Uganda cattle using a metagenomics approach. We used the SqueezeMeta-Abricate (assembly-based) pipeline to detect ARGs and benchmarked this approach using the Centifuge-AMRplusplus (read-based) pipeline to evaluate its efficiency. Our findings reveal a significant number of ARGs of critical medical and economic importance in all three countries, including resistance to drugs of last resort such as carbapenems, suggesting the presence of highly virulent and antibiotic-resistant bacterial pathogens (ESKAPE) circulating in East Africa. Shared ARGs such as aph(6)-id (aminoglycoside phosphotransferase), tet (tetracycline resistance gene), sul2 (sulfonamide resistance gene) and cfxA_gen (betalactamase gene) were detected. Assembly-based methods revealed fewer ARGs compared to read-based methods, indicating the sensitivity and specificity of read-based methods in resistome characterization. Our findings call for further surveillance to estimate the intensity of the antibiotic resistance problem and wider resistome classification. Effective management of livestock and antibiotic consumption is crucial in minimizing antimicrobial resistance and maximizing productivity, making these findings relevant to stakeholders, agriculturists, and veterinarians in East Africa and Africa at large.

Meta-Analysis and Systematic Review of Phenotypic and Genotypic Antimicrobial Resistance and Virulence Factors in Vibrio parahaemolyticus Isolated from Shrimp

This systematic review and meta-analysis investigates the prevalence of Vibrio parahaemolyticus, its virulence factors, antimicrobial resistance (AMR), and its resistance determinants in shrimp. This study was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, to identify and select relevant peer-reviewed articles published between January 2020 and December 2022. The search strategy involved multiple online databases, including Google Scholar, PubMed, ScienceDirect, and Scopus. The inclusion criteria focused on studies that examined V. parahaemolyticus prevalence, virulence factors, and AMR in shrimp from farms to retail outlets. A total of 32 studies were analyzed, revealing a pooled estimate prevalence of V. parahaemolyticus in shrimp at 46.0%, with significant heterogeneity observed. Subgroup analysis highlighted varying prevalence rates across continents, emphasizing the need for further investigation. Virulence factor analysis identified thermostable direct hemolysin (tdh) and tdh-related hemolysin (trh) as the most common. Phenotypic AMR analysis indicated notable resistance to glycopeptides, nitrofurans, and beta-lactams. However, the correlation between antimicrobial usage in shrimp farming and observed resistance patterns was inconclusive. Funnel plots suggested potential publication bias, indicating a need for cautious interpretation of findings. This study underscores the urgency of coordinated efforts to address AMR in V. parahaemolyticus to safeguard public health and to ensure sustainable aquaculture practices.

The level of knowledge of medical and dental students regarding prophylaxis for infective endocarditis

OBJECTIVES

Infective endocarditis is a rarely seen disease, but has a high mortality rate. Therefore, it is extremely important that the guidelines are followed correctly. The main aim of this study was to evaluate and compare the level of knowledge and attitude of infective endocarditis of fourth- and fifth-year dentistry students in clinical residency and fifth- and sixth-year medical students.

METHODS

A 42-item questionnaire evaluating the type and dosage of antibiotics administered as infective endocarditis prophylaxis in medical conditions and dentistry procedures was delivered online to the study participants. The data obtained were examined using descriptive statistics and analyzed with the chi-square test.

RESULTS

The questionnaire was completed by a total of 332 participants. The statistical analyses showed a good level of knowledge in 55% of the dentistry faculty students and in 43.5% of the medical faculty students.

CONCLUSIONS

When considering that dental and medical faculty students are not expected to receive additional training on antimicrobial management after graduation, the findings of this study have raised significant attitude for the improvement of our education system in this field.

Evaluation of cattle farmers' knowledge, attitudes, and practices regarding antimicrobial use and antimicrobial resistance in Rwanda

The misuse of antimicrobials in livestock may lead to the emergence and spread of resistant pathogens harmful to human, animal, and environmental health. Therefore, determining the behavior and practices of farmers regarding antimicrobial use (AMU) and antimicrobial resistance (AMR) is crucial for addressing the growing threat of AMR. This cross-sectional study was conducted in the Eastern Province of Rwanda on 441 participants using a structured questionnaire to determine the knowledge, attitudes, and practices (KAP) towards AMU and AMR. Frequency distributions, chi-square test of association and logistic regression model were used to analyze the data. This study showed poor biosecurity measures at the farm level with various antimicrobials used here; 83.9% of participants obtained them from friends and neighbors and 61.9% used them for growth promotion. Our assessment revealed a low level of KAP towards AMR among cattle farmers from the study districts. Our data showed that at a 69% cutoff, only 52.6% of farmers had correct knowledge, whereas 56% had good attitudes (47% cutoff). Finally, 52.8% had correct practices toward AMR based on a calculated cutoff of 50%. Positive attitudes, correct knowledge, and practices regarding AMU and AMR were associated with higher educational levels. Sex was correlated with knowledge and attitudes, whereas farm location was associated with attitudes and practices. Farmers expressed a need for more access to veterinary services and AMR-related training for themselves, the community animal health workers, and veterinarians. This study highlighted the low levels of KAP associated with using antimicrobials, which may lead to the misuse of antimicrobials and the spread of AMR. It is imperative to develop and implement cross-cutting measures to minimize antibiotic usage and reduce the risk of antibiotic resistance.

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.

Patients' Opinions on Antibiotics in the Treatment of Dental Infections: A Cross-Sectional Survey

Background: The aim of this study was to evaluate patients' knowledge and perceptions of the use of systemic antibiotics in the treatment of endodontic infections and to determine the possible contribution of patients to the development of bacterial resistance. Methods: A total of 550 patients were asked to respond to a survey on the perception of systemic antibiotic use in the treatment of endodontic infections and antibiotic resistance during January 2022 and March 2023. A bivariate and multivariate analysis was performed to determine possible correlates in the population regarding antibiotic use in the endodontic world. Results: A total of 514 patients were included in the study, 65.9% of whom were women. While 34.6% of the population studied thought that it was always necessary to take antibiotics prior to endodontics, 49.4% considered that they were necessary after endodontics, regardless of the clinical symptoms. The prevalence of self-medication was 17.3%, and women self-medicate more than men, with significant differences (p < 0.05), although they have a greater knowledge of antibiotic resistance than men (p < 0.05). Forty-four percent of the population expected to take antibiotics when faced with dental pain, mainly women (p < 0.05). Conclusions: The general population is contributing to the serious problem of bacterial resistance. It is necessary to promote educational strategies focused on the correct use of antibiotics in the community. The worst results were found mainly in the population with a low level of education. The level of education was the variable that most influenced the knowledge and attitudes of the population, followed by the sex of the participants.

The Peptide Antibiotic Corramycin Adopts a β-Hairpin-like Structure and Is Inactivated by the Kinase ComG

The rapid development of antibiotic resistance, especially among difficult-to-treat Gram-negative bacteria, is recognized as a serious and urgent threat to public health. The detection and characterization of novel resistance mechanisms are essential to better predict the spread and evolution of antibiotic resistance. Corramycin is a novel and modified peptidic antibiotic with activity against several Gram-negative pathogens. We demonstrate that the kinase ComG, part of the corramycin biosynthetic gene cluster, phosphorylates and thereby inactivates corramycin, leading to the resistance of the host. Remarkably, we found that the closest structural homologues of ComG are aminoglycoside phosphotransferases; however, ComG shows no activity toward this class of antibiotics. The crystal structure of ComG in complex with corramycin reveals that corramycin adopts a β-hairpin-like structure and allowed us to define the changes leading to a switch in substrate from sugar to peptide. Bioinformatic analyses suggest a limited occurrence of ComG-like proteins, which along with the absence of cross-resistance to clinically used drugs positions corramycin as an attractive antibiotic for further development.

Nanowarriors from Mentha: Unleashing Nature's Antimicrobial Arsenal with Cerium Oxide Nanoparticles

Medicinal plant-based cerium oxide nanoparticles (CeO2NPs) possessed excellent antimicrobial properties against multiple strains of Gram-positive and Gram-negative bacteria. The CeO2NPs are popular because their electropositive charged surface causes oxidation of plasma membrane and facilitates the penetration of CeO2NPs inside the pathogen body. In the present research work, CeO2NPs stabilized with Mentha leaf extract; as a result, nanoparticles surface-bonded with various functional groups of phytochemicals which enhanced the therapeutic potential of CeO2NPs. The inhibition percentage of CeO2NPs was evaluated against eight pathogenic Gram-positive bacteria Staphylococcus aureus and Streptococcus epidermidis; Gram-negative bacteria Escherichia coli, Stenotrophomonas maltophilia, Comamonas sp., Halobacterium sp., and Klebsiella pneumoniae; and plant bacteria Xanthomonas sp. The antifungal properties of CeO2NPs were evaluated against three pathogenic fungal species Bipolaris sorokiniana, Aspergillus flavus, and Fusarium oxysporum via the streak plate method. The antimicrobial inhibitory activity of CeO2NPs was good to excellent. The current research work clearly shows that three different medicinal plants Mentha royleana, Mentha longifolia, and Mentha arvensis based CeO2NPs, variation in nanoparticle sizes, and surface-to-volume ratio of green CeO2NPs are three factors responsible to generate and provoke antimicrobial activities of CeO2NPs against human pathogenic bacteria and plant infecting fungi. The results show that CeO2NPs possessed good antimicrobial properties and are effective to use for pharmaceutical applications and as a food preservative because of low toxicity, organic coating, and acceptable antimicrobial properties. This study showed a rapid and well-organized method to prepare stable phytochemical-coated CeO2NPs with three different plants M. royleana, M. longifolia, and M. arvensis with remarkable antibacterial and antifungal characteristics.

Evaluation of three protocols for direct susceptibility testing for Gram-negative rods from flagged positive blood culture bottles

Bloodstream infections are associated with high mortality, which can be reduced by targeted antibiotic therapy in the early stages of infection. Direct antibiotic susceptibility testing (AST) from flagged positive blood cultures may facilitate the administration of early effective antimicrobials much before the routine AST. This study aimed to evaluate three different direct AST protocols for Gram-negative rods from flagged positive blood culture broths. Blood culture broths showing Gram-negative rods only were subjected to direct AST by Clinical and Laboratory Standards Institute-recommended direct disk diffusion (protocol A). Additionally, automated AST (protocol B) and Kirby-Bauer disk diffusion (protocol C) were performed with standard inoculum prepared from bacterial pellets obtained by centrifuging blood culture broths in serum separator vials. For comparison, conventional AST of isolates from solid media subculture was also performed with Kirby-Bauer disk diffusion (reference standard) and the automated method. Overall, categorical agreements of protocols A, B, and C were 97.6%, 95.7%, and 95.9%, respectively. Among Enterobacterales, minor error, major error, and very major error rates of protocol B were 3.5%, 0.36%, and 0.43%, respectively, whereas minor error, major error, and very major error rates of protocol C were 3.4%, 0.72%, and 0.21%, respectively, and among non-fermenters, protocol B had a minor error rate of 6.5%, and protocol C had a minor error rate of 4.1% and major error rate of 1.9%. All three direct AST protocols demonstrated excellent categorical agreements with the reference method. Performance of protocols B and C between Enterobacterales and non-fermenters was not statistically different.

IMPORTANCE

Bloodstream infections are associated with high mortality that can be reduced by targeted antibiotic therapy in the early stages of infection. Direct antibiotic susceptibility testing (AST) from flagged positive blood cultures may facilitate the administration of early effective antimicrobials much before the routine AST. Clinical and Laboratory Standards Institute-recommended direct AST can be performed with a limited number of antibiotic disks only. On the other hand, using an automated system for direct AST will not only allow effective laboratory workflow with reduced turnaround time but also provide the minimum inhibitory concentration values of tested antibiotics. However, using expensive automated systems for direct AST may not be feasible for resource-limited laboratories. Therefore, in this study, we aimed to evaluate the CLSI-recommended method and two other direct AST protocols (one with an automated system and the other with disk diffusion) for Gram-negative rods from flagged positive blood cultures.

Phenotypic and Genotypic Characterizations of Antimicrobial-Resistant Escherichia coli Isolates from Diverse Retail Meat Samples in North Carolina During 2018-2019

Surveillance of antimicrobial-resistant pathogens in U.S. retail meats is conducted to identify potential risks of foodborne illness. In this study, we conducted a phenotypic and genotypic analysis of Escherichia coli recovered from a diverse range of retail meat types during 2018-2019 in North Carolina. The investigation was conducted as part of the National Antimicrobial Resistance Monitoring System (NARMS). Retail meat sampling and E. coli isolation were performed in accordance with NARMS retail meat isolation protocols. We used the Sensititre™ broth microdilution system to determine phenotypic resistance to 14 antimicrobial agents and the Illumina next-generation sequencing platform for genotypic resistance profiling. The highest prevalence of E. coli isolates was found in ground turkey (n = 57, 42.9%) and chicken (n = 27, 20.3%), followed by ground beef (n = 25, 18.9%) and pork (n = 24, 18%). The isolates were divided into seven different phylogroups using the Clermont typing tool, with B1 (n = 59, 44.4%) and A (n = 39, 29.3%) being the most dominant, followed by B2 (n = 14, 10.5%), D (n = 7, 5.3%), F (n = 6, 4.5%), E (n = 3, 2.3%), and C (n = 2, 1.5%). Using multilocus sequence typing (MLST), 128 Sequence types (STs) were identified indicating high diversity. Phenotypic and genotypic resistance was observed toward aminoglycosides, sulfonamides, beta-lactams, macrolides, tetracyclines, phenicols, and fluoroquinolones. Ground turkey samples were more resistant to the panel of tested antimicrobials than chicken, beef, or pork (p < 0.05). All isolates were found to be susceptible to meropenem. A high percentage of turkey isolates (n = 16, 28%) were multidrug-resistant (MDR) compared with 18.5% of chicken (n = 5), 8.4% of pork (n = 2), and 8% of beef isolates (n = 2). This study highlights the benefit of surveillance to identify MDR E. coli for epidemiologic tracking and is a comprehensive report of the phenotypic and genotypic characterization of E. coli isolated from retail meats in North Carolina.

Development and evaluation of 2,4-disubstituted-5-aryl pyrimidine derivatives as antibacterial agents

Designing novel candidates as potential antibacterial scaffolds has become crucial due to the lack of new antibiotics entering the market and the persistent rise in multidrug resistance. Here, we describe a new class of potent antibacterial agents based on a 5-aryl-N2,N4-dibutylpyrimidine-2,4-diamine scaffold. Structural optimization focused on the 5-aryl moiety and the bioisosteric replacement of the side chain linker atom. Screening of the synthesized compounds focused on a panel of bacterial strains, including gram-positive Staphylococcus aureus strains (Newman MSSA, methicillin- and vancomycin-resistant), and the gram-negative Escherichia coli (ΔAcrB strain). Several compounds showed broad-spectrum antibacterial activity with compound 12, bearing a 4-chlorophenyl substituent, being the most potent among this series of compounds. This frontrunner compound revealed a minimum inhibitory concentration (MIC) value of 1 µg/mL against the S. aureus strain (Mu50 methicillin-resistant S. aureus/vancomycin-intermediate S. aureus) and an MIC of 2 µg/mL against other tested strains. The most potent derivatives were further tested against a wider panel of bacteria and evaluated for their cytotoxicity, revealing further potent activities toward Streptococcus pneumoniae, Enterococcus faecium, and Enterococcus faecalis. To explore the mode of action, compound 12 was tested in a macromolecule inhibition assay. The obtained data were supported by the safety profile of compound 12, which possessed an IC50 of 12.3 µg/mL against HepG2 cells. The current results hold good potential for a new class of extended-spectrum antibacterial agents.

Interaction of tetracycline and copper co-intake in inducing antibiotic resistance genes and potential pathogens in mouse gut

The widespread use of copper and tetracycline as growth promoters in the breeding industry poses a potential threat to environmental health. Nevertheless, to the best of our knowledge, the potential adverse effects of copper and tetracycline on the gut microbiota remain unknown. Herein, mice were fed different concentrations of copper and/or tetracycline for 6 weeks to simulate real life-like exposure in the breeding industry. Following the exposure, antibiotic resistance genes (ARGs), potential pathogens, and other pathogenic factors were analyzed in mouse feces. The co-exposure of copper with tetracycline significantly increased the abundance of ARGs and enriched more potential pathogens in the gut of the co-treated mice. Copper and/or tetracycline exposure increased the abundance of bacteria carrying either ARGs, metal resistance genes, or virulence factors, contributing to the widespread dissemination of potentially harmful genes posing a severe risk to public health. Our study provides insights into the effects of copper and tetracycline exposure on the gut resistome and potential pathogens, and our findings can help reduce the risks associated with antibiotic resistance under the One Health framework.

The Tradeoffs Between Persistence and Mutation Rates at Sub-Inhibitory Antibiotic Concentrations in Staphylococcus aureus

The rational design of the antibiotic treatment of bacterial infections employs these drugs to reach concentrations that exceed the minimum needed to prevent the replication of the target bacteria. However, within a treated patient, spatial and physiological heterogeneity promotes antibiotic gradients such that the concentration of antibiotics at specific sites is below the minimum needed to inhibit bacterial growth. Here, we investigate the effects of sub-inhibitory antibiotic concentrations on three parameters central to bacterial infection and the success of antibiotic treatment, using in vitro experiments with Staphylococcus aureus and mathematical-computer simulation models. Our results, using drugs of six different classes, demonstrate that exposure to sub-inhibitory antibiotic concentrations not only alters the dynamics of bacterial growth but also increases the mutation rate to antibiotic resistance and decreases the rate of production of persister cells thereby reducing the persistence level. Understanding this trade-off between mutation rates and persistence levels resulting from sub-inhibitory antibiotic exposure is crucial for optimizing, and mitigating the failure of, antibiotic therapy.

Hydrocarbon stapled temporin-L analogue as potential antibacterial and antiendotoxin agents with enhanced protease stability

Antimicrobial resistance (AMR) is a serious global concern and a huge burden on the healthcare system. Antimicrobial peptides (AMPs) are considered as a solution of AMR due to their membrane-lytic and intracellular mode of action and therefore resistance development against AMPs is less frequent. One such AMPs, temporin-L (TL) is a 13-mer peptide reported as a potent and broad-spectrum antibacterial agent with significant immunomodulatory activity. However, TL is toxic to human erythrocytes at their antibacterial concentrations and therefore various analogues were synthesized with potent antimicrobial activity and lower hemolytic activity. In this work, we have selected a non-toxic engineered analogue of TL (eTL) and performed hydrocarbon stapling of amino acid residues at i to i + 4 positions at different part of sequence. The synthesized peptides were investigated against both the gram-positive and gram-negative bacteria as well as methicillin resistant S. aureus, its MIC was measured in the concentrations range of 0.9-15.2 µM. All analogues were found equal or better antibacterial as compared to parent peptide. Interestingly one analogue eTL [5-9] was found to be non-cytotoxic and stable in presence of the human serum. Mode of action studies revealed membrane depolarizing and disruptive mode of action with live MRSA. Further in vivo studies of antimicrobial against MRSA infection and anti-endotoxin activities in mice model revealed potential activity of the stapled peptide analogue. Overall, this reports on stapled analogue of the AMPs highlights an important strategy for the development of new antibacterial therapeutics against AMR.

Global diversity, coexistence and consequences of resistome in inland waters

Human activities have long impacted the health of Earth's rivers and lakes. These inland waters, crucial for our survival and productivity, have suffered from contamination which allows the formation and spread of antibiotic-resistant genes (ARGs) and consequently, ARG-carrying pathogens (APs). Yet, our global understanding of waterborne pathogen antibiotic resistance remains in its infancy. To shed light on this, our study examined 1240 metagenomic samples from both open and closed inland waters. We identified 22 types of ARGs, 19 types of mobile genetic elements (MGEs), and 14 types of virulence factors (VFs). Our findings showed that open waters have a higher average abundance and richness of ARGs, MGEs, and VFs, with more robust co-occurrence network compared to closed waters. Out of the samples studied, 321 APs were detected, representing a 43 % detection rate. Of these, the resistance gene 'bacA' was the most predominant. Notably, AP hotspots were identified in regions including East Asia, India, Western Europe, the eastern United States, and Brazil. Our research underscores how human activities profoundly influence the diversity and spread of resistome. It also emphasizes that both abiotic and biotic factors play pivotal roles in the emergence of ARG-carrying pathogens.

Trinitroglycerin-loaded chitosan nanogels: Shedding light on cytotoxicity, antioxidativity, and antibacterial activities

AIM AND BACKGROUND

Trinitroglycerin (TNG) is a remarkable NO-releasing agent. Here, we synthesized TNG based on chitosan Nanogels (Ngs) for ameliorating complications associated with high-dose TNG administration.

METHOD

TNG-Ngs fabricated through ionic-gelation technique. Fourier-transformed infrared (FT-IR), zeta-potential, dynamic light scattering (DLS), and electron microscopy techniques evaluated the physicochemical properties of TNG-Ngs. MTT was used to assess the biocompatibility of TNG-Ngs, as the antioxidative properties were determined via lactate dehydrogenase (LDH), reactive oxygen species (ROS), and lipid peroxide (LPO) assays. The antibacterial activity was evaluated against Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), Methicillin-resistant Staphylococcus aureus (MRSA), and vancomycin-resistant Enterococci (VRE).

RESULTS

Physicochemical characterization reveals that TNG-Ngs with size diameter (96.2 ± 29 nm), polydispersity index (PDI, 0.732), and negative zeta potential (-1.1 mv) were fabricated. The encapsulation efficacy (EE) and loading capacity (LC) were obtained at 71.1 % and 2.3 %, respectively, with no considerable effect on particle size and morphology. The cytotoxicity assay demonstrated that HepG2 cells exposed to TNG-Ngs showed relative cell viability (RCV) of >80 % for 70 μg/ml compared to the TNG-free drug at the same concentration (P < 0.05). TNG-Ngs showed significant differences with the TNG-free drug for LDH, LPO, and ROS formation at the same concentration (P < 0.001). The antibacterial activity of the TNG-Ngs against S. aureus, E. coli, VRE, and MRSA was higher than the TNG-free drug and Ngs (P < 0.05).

CONCLUSION

TNG-Ngs with enhanced antibacterial and antioxidative activity and no obvious cytotoxicity might be afforded as novel nanoformulation for promoting NO-dependent diseases.

The link between physician motivation and care

Studies report an unexplained variation in physicians' care. This variation may to some extent be explained by differences in their work motivation. However, empirical evidence on the link between physician motivation and care is scarce. We estimate the associations between different types of work motivation and care. Motivation is measured using validated questions from a nation-wide survey of Danish general practices and linked to high-quality register data on their care in 2019. Using a series of regression models, we find that more financially motivated practices generate more fee-for-services per patient, whereas practices characterised by greater altruistic motivation towards the patient serve a larger share of high-need patients and issue more prescriptions for antibiotics per patient. Practices with higher altruism towards society generate lower medication costs per patient and prescribe a higher rate of narrow-spectrum penicillin, thereby reducing the risk of antimicrobial resistance in the population. Together, our results suggest that practices' motivation is associated with several dimensions of healthcare, and that both their financial motivation and altruism towards patients and society play a role. Policymakers should, therefore, consider targeting all provider motivations when introducing organisational changes and incentive schemes; for example, by paying physicians to adhere to clinical guidelines, while at the same time clearly communicating the guidelines' value from both a patient and societal perspective.

Community antibiotic consumption and associated factors in Lusaka district of Zambia: findings and implications for antimicrobial resistance and stewardship

Introduction

Antimicrobial resistance (AMR) is a global public health crisis. This study assessed the general public's consumption of antibiotics and associated factors in the Lusaka district of Zambia.

Methods

This cross-sectional study was conducted among 2038 participants between December 2022 and January 2023. Data were analysed using Stata 13.0. Multivariable regression techniques were used to determine the factors that influenced antibiotic consumption.

Results

Of the 2038 participants, 53.4% were female, and 51.5% had attended at least secondary school. Antibiotic use was 99.2%, of which 40.9% were appropriately used. Overall, 79.1% of antibiotics were prescribed in hospitals, while 20.9% were used from leftovers and accessed without prescriptions. This study found that the appropriate use of antibiotics was associated with being female, being aged 35 years and above, attaining secondary school or tertiary education, having a monthly expenditure of 195 USD and above, being aware that antibiotics were not the same as painkillers, and being confident that when someone was hospitalized, they would get well.

Conclusions

This study found that the appropriate use of antibiotics was low, and this is an urgent public health issue requiring community engagement in tackling AMR and adherence to treatment guidelines in healthcare facilities. Additionally, there is a need to implement and strengthen antimicrobial stewardship programmes in healthcare facilities to promote the rational use of antibiotics in Zambia. There is also a need to heighten community awareness campaigns and educational activities on the appropriate use of antibiotics.

Epidemiology, Clinical, and Microbiological Characteristics of Multidrug-Resistant Gram-Negative Bacteremia in Qatar

Antimicrobial resistance is a global healthcare threat with significant clinical and economic consequences peaking at secondary and tertiary care hospitals where multidrug-resistant Gram-negative bacteria (MDR GNB) lead to poor outcomes. A prospective study was conducted between January and December 2019 for all invasive bloodstream infections (BSIs) secondary to MDR GNB in Qatar identified during routine microbiological service to examine their clinical, microbiological, and genomic characteristics. Out of 3238 episodes of GNB BSIs, the prevalence of MDR GNB was 13% (429/3238). The predominant MDR pathogens were Escherichia coli (62.7%), Klebsiella pneumoniae (20.4%), Salmonella species (6.6%), and Pseudomonas aeruginosa (5.3%), while out of 245 clinically evaluated patients, the majority were adult males, with the elderly constituting almost one-third of the cohort and with highest observed risk for prolonged hospital stays. The risk factors identified included multiple comorbidities, recent healthcare contact, previous antimicrobial therapy, and admission to critical care. The in-hospital mortality rate was recorded at 25.7%, associated with multiple comorbidities, admission to critical care, and the acquisition of MDR Pseudomonas aeruginosa. Resistant pathogens demonstrated high levels of antimicrobial resistance but noticeable susceptibility to amikacin and carbapenems. Genomic analysis revealed that Escherichia coli ST131 and Salmonella enterica ST1 were the predominant clones not observed with other pathogens.

Antimicrobial Activity of Bacillus amyloliquefaciens BS4 against Gram-Negative Pathogenic Bacteria

Worldwide, bacterial resistance is one of the most severe public health problems. Currently, the failure of antibiotics to counteract superbugs highlights the need to search for new molecules with antimicrobial potential to combat them. The objective of this research was to evaluate the antimicrobial activity of Bacillus amyloliquefaciens BS4 against Gram-negative bacteria. Thirty yeasts and thirty-two Bacillus isolates were tested following the agar well-diffusion method. Four Bacillus sp. strains (BS3, BS4, BS17, and BS21) showed antagonistic activity against E. coli ATCC 25922 using bacterial culture (BC) and the cell-free supernatant (CFS), where the BS4 strain stood out, showing inhibitory values of 20.50 ± 0.70 mm and 19.67 ± 0.58 mm for BC and CFS, respectively. The Bacillus sp. BS4 strain can produce antioxidant, non-hemolytic, and antimicrobial metabolites that exhibit activity against several microorganisms such as Salmonella enterica, Klebsiella pneumoniae, Shigella flexneri, Enterobacter aerogenes, Proteus vulgaris, Yersinia enterocolitica, Serratia marcescens, Aeromonas sp., Pseudomonas aeruginosa, Candida albicans, and Candida tropicalis. According to the characterization of the supernatant, the metabolites could be proteinaceous. The production of these metabolites is influenced by carbon and nitrogen sources. The most suitable medium to produce antimicrobial metabolites was TSB broth. The one-factor-at-a-time method was used to standardize parameters such as pH, agitation, temperature, carbon source, nitrogen source, and salts, resulting in the best conditions of pH 7, 150 rpm, 28 °C, starch (2.5 g/L), tryptone (20 g/L), and magnesium sulfate (0.2 g/L), respectively. Moreover, the co-culture was an excellent strategy to improve antimicrobial activity, achieving maximum antimicrobial activity with an inhibition zone of 21.85 ± 1.03 mm. These findings position the Bacillus amyloliquefaciens BS4 strain as a promising candidate for producing bioactive molecules with potential applications in human health.

Characterizing Antibiotic Regimen Modification Behavior, Patient Characteristics, and Outcomes for Patients with Gram-Negative Bacterial Infections, A Retrospective Single-Center Study

Few studies describe the frequency of antibiotic regimen modification behaviors in the acute care setting. We sought to ascertain patient and treatment characteristics, details of regimen modification, and clinical outcomes with antibiotic modifications. This retrospective study included patients admitted to Hoag Memorial Hospital from 1 January 2019-31 March 2021 with a complicated infection caused by a Gram-negative organism resistant to extended-spectrum cephalosporins or with the potential for resistance (AmpC producers). A total of 400 patients were included. The predominant sources were bloodstream (33%), urine (26%), and respiratory (24%), including patients with multiple sources. The most isolated organisms were Pseudomonas spp. and ESBL-producing organisms, 38% and 34%, respectively. A total of 72% of patients had antibiotic regimen modifications to their inpatient antibiotic regimens. In patients where modifications occurred, the number ranged from one to six modifications. The most common reasons for modifications included a lack of patient response (14%), additional history reviewed (9%), and decompensation (7%). No difference in clinical outcomes was observed based on antibiotic modifications. The numerous changes in therapy observed may reflect the limitations in identifying patients with resistant organisms early on in admission. This highlights the need for more novel antibiotics and the importance of identifying patients at risk for resistant organisms.

Selenium-silk microgels as antifungal and antibacterial agents

Antimicrobial resistance is a leading threat to global health. Alternative therapeutics to combat the rise in drug-resistant strains of bacteria and fungi are thus needed, but the development of new classes of small molecule therapeutics has remained challenging. Here, we explore an orthogonal approach and address this issue by synthesising micro-scale, protein colloidal particles that possess potent antimicrobial properties. We describe an approach for forming silk-based microgels that contain selenium nanoparticles embedded within the protein scaffold. We demonstrate that these materials have both antibacterial and antifungal properties while, crucially, also remaining highly biocompatible with mammalian cell lines. By combing the nanoparticles with silk, the protein microgel is able to fulfill two critical functions; it protects the mammalian cells from the cytotoxic effects of the bare nanoparticles, while simultaneously serving as a carrier for microbial eradication. Furthermore, since the antimicrobial activity originates from physical contact, bacteria and fungi are unlikely to develop resistance to our hybrid biomaterials, which remains a critical issue with current antibiotic and antifungal treatments. Therefore, taken together, these results provide the basis for innovative antimicrobial materials that can target drug-resistant microbial infections.

Unraveling the ligand specificity and promiscuity of the Staphylococcus aureus NorA efflux pump: a computational study

Staphylococcus aureus, a gram-positive bacterial pathogen, develops antibiotic resistance partly through enhanced activity of transmembrane multi-drug efflux pump proteins like NorA. Being a prominent member of the Major Facilitator Superfamily (MFS), NorA transports various small molecules including hydrophilic fluoroquinolone antibiotics across the cell membrane. Intriguingly, NorA is inhibited by a structurally diverse set of small molecule inhibitors as well, indicating a highly promiscuous ligand/inhibitor recognition. Our study aims to elucidate the structural facets of this promiscuity. Known NorA inhibitors were grouped into five clusters based on chemical class and docked into ligand binding pockets on NorA conformations generated via molecular dynamics simulations. We discovered that several key residues, such as I23, E222, and F303, are involved in inhibitor binding. Additionally, residues I244, T223, F303, and F140 were identified as prominent in interactions with specific ligand clusters. Our findings suggest that NorA's substrate binding site, encompassing residues aiding ligand recognition based on chemical nature, facilitates the recognition of chemically diverse ligands. This insight into NorA's structural promiscuity in ligand recognition not only enhances understanding of antibiotic resistance mechanisms in S. aureus but also sets the stage for the development of more effective efflux pump inhibitors, vital for combating multidrug resistance.Communicated by Ramaswamy H. Sarma.

Protecting the Last Line of Defense: Analytical Approaches for Sample Preparation and Determination of the Reserve Group of Antibiotics in the Environment

Drug resistance in microorganisms is a serious threat to life and health due to the limited number of antibiotics that show efficacy in treating infections and the difficulty in discovering new compounds with antibacterial activity. To address this issue, the World Health Organization created the AWaRe classification, a tool to support global and national antimicrobial stewardship programs. The AWaRe list categorizes antimicrobials into three groups - Access, Watch, and Reserve - according to their intended use. The Reserve group comprises "last resort" medicines used solely for treating infections caused by bacterial strains that are resistant to other treatments. It is therefore necessary to protect them, not only by using them as prudently as possible in humans and animals, but also by monitoring their subsequent fate. Unmetabolized antibiotics enter the environment through hospital and municipal wastewater or from manure, subsequently contaminating bodies of water and soils, thus contributing to the emergence and spread of antibiotic resistance. This article presents a review of determination methods for the Reserve group of antimicrobials in water, wastewater, and manure. Procedures for extracting and determining these substances in environmental samples are described, showing the limited research available, which is typically on a local level.

EFFECT OF PENICILLIUM SPECIES ON THE ANTIBIOTIC RESISTANCE PROFILE OF ALCALIGENES FAECALIS

Background

Infectious diseases due to antibiotic resistant pathogens are a global public health problem. This study aimed at determining the potential effect of bacterial-fungal interaction on the antibiotic susceptibility profile of Alcaligenes faecalis.

Materials and Methods

Alcaligenes faecalis was isolated from water samples. The isolate was identified using the conventional biochemical tests and the 16S rRNA molecular sequencing technique. Additionally, Penicillium species was isolated and identified based on colony morphological characteristics and microscopic features. Standardized isolates were co-cultured in broth medium. Antibiotic susceptibility evaluation of the Alcaligenes faecalis from the co-culture and the original Alcaligenes faecalis was carried out using the Kirby bauer disk diffusion method.

Results

The antibiotic susceptibility profile of Alcaligenes faecalis before and after co-culture remained largely unchanged except in the case of chloramphenicol, where the isolate showed reduced susceptibility. Molecular analysis of resistance gene revealed the absence of tested gene encoding antibiotic resistance, including the streptomycin resistance (str) genes (stra and strb) and the erythromycin resistance methylase (erm) gene.

Conclusion

The result of this study showed that there is a minimal influence of Penicillium cultures on the susceptibility of A. faecalis. Further research involving a wide spectrum of microorganisms and their interactions should be conducted to acquire a thorough understanding of the influence of microbial interactions on antibiotic susceptibility profiles in order to pave way for novel strategies to combat antimicrobial resistance.

Unveiling biological activities of biosynthesized starch/silver-selenium nanocomposite using Cladosporium cladosporioides CBS 174.62

BACKGROUND AND OBJECTIVES

Microbial cells capability to tolerate the effect of various antimicrobial classes represent a major worldwide health concern. The flexible and multi-components nanocomposites have enhanced physicochemical characters with several improved properties. Thus, different biological activities of biosynthesized starch/silver-selenium nanocomposite (St/Ag-Se NC) were assessed.

METHODOLOGY

The St/Ag-Se NC was biosynthesized using Cladosporium cladosporioides CBS 174.62 (C. cladosporioides) strain. The shape and average particle size were investigated using scanning electron microscope (SEM) and high-resolution transmission electron microscope (HR-TEM), respectively. On the other hand, the St/Ag-Se NC effect on two cancer cell lines and red blood cells (RBCs) was evaluated and its hydrogen peroxide (H2O2) scavenging effect was assessed. Moreover, its effects on various microbial species in both planktonic and biofilm growth forms were examined.

RESULTS

The St/Ag-Se NC was successfully biosynthesized with oval and spherical shape and a mean particle diameter of 67.87 nm as confirmed by the HR-TEM analysis. St/Ag-Se NC showed promising anticancer activity toward human colorectal carcinoma (HCT-116) and human breast cancer (MCF-7) cell lines where IC50 were 21.37 and 19.98 µg/ml, respectively. Similarly, little effect on RBCs was observed with low nanocomposite concentration. As well, the highest nanocomposite H2O2 scavenging activity (42.84%) was recorded at a concentration of 2 mg/ml. Additionally, Staphylococcus epidermidis (S. epidermidis) ATCC 12,228 and Candida albicans (C. albicans) ATCC 10,231 were the highly affected bacterial and fungal strains with minimum inhibitory concentrations (MICs) of 18.75 and 50 µg/ml, respectively. Moreover, the noticeable effect of St/Ag-Se NC on microbial biofilm was concentration dependent. A high biofilm suppression percentage, 87.5% and 68.05%, were recorded with S. epidermidis and Staphylococcus aureus (S. aureus) when exposed to 1 mg/ml and 0.5 mg/ml, respectively.

CONCLUSION

The biosynthesized St/Ag-Se NC showed excellent antioxidant activity, haemocompatibility, and anti-proliferative effect at low concentrations. Also, it exhibited promising antimicrobial and antibiofilm activities.

Dynamic Adaptation in Extant Porins Facilitates Antibiotic Tolerance in Energetic Escherichia coli

Bacteria can tolerate antibiotics despite lacking the genetic components for resistance. The prevailing notion is that tolerance results from depleted cellular energy or cell dormancy. In contrast to this view, many cells in the tolerant population of Escherichia coli can exhibit motility - a phenomenon that requires cellular energy, specifically, the proton-motive force (PMF). As these motile-tolerant cells are challenging to isolate from the heterogeneous tolerant population, their survival mechanism is unknown. Here, we discovered that motile bacteria segregate themselves from the tolerant population under micro-confinement, owing to their unique ability to penetrate micron-sized channels. Single-cell measurements on the motile-tolerant population showed that the cells retained a high PMF, but they did not survive through active efflux alone. By utilizing growth assays, single-cell fluorescence studies, and chemotaxis assays, we showed that the cells survived by dynamically inhibiting the function of existing porins in the outer membrane. A drug transport model for porin-mediated intake and efflux pump-mediated expulsion suggested that energetic tolerant cells withstand antibiotics by constricting their porins. The novel porin adaptation we have uncovered is independent of gene expression changes and may involve electrostatic modifications within individual porins to prevent extracellular ligand entry.

Crystal structure of GTPase YsxC from Staphylococcus aureus

The YsxC protein from Staphylococcus aureus is a GTP-binding protein from the TRAFAC superfamily of the TrmE-Era-EngA-EngB-Septin-like GTPase class, EngB family of GTPases. Recent structural and biochemical studies of YsxC function show that it is an integral part of the pathogenic microorganism life cycle, as it is involved in the assembly of the large 50S ribosomal subunit. Structural studies of this protein with its specific functional features make it an attractive target for further development of new selective antimicrobials. In this study, we cloned the ysxC protein gene from S. aureus, overexpressed the protein in E. coli, and subsequently purified and crystallized it. Protein crystals were successfully grown using the vapor diffusion method, yielding diffraction data with a resolution of up to 2 Å. Comparative analysis of the structure of SaYsxC with known three-dimensional structures of homologs from other microorganisms showed the presence of structural differences for the apo form.

Pharmacokinetics and Biodistribution of Phages and their Current Applications in Antimicrobial Therapy

Antimicrobial resistance remains a critical global health concern, necessitating the investigation of alternative therapeutic approaches. With the diminished efficacy of conventional small molecule drugs due to the emergence of highly resilient bacterial strains, there is growing interest in the potential for alternative therapeutic modalities. As naturally occurring viruses of bacteria, bacteriophage (or phage) are being re-envisioned as a platform to engineer properties that can be tailored to target specific bacterial strains and employ diverse antibacterial mechanisms. However, limited understanding of key pharmacological properties of phage is a major challenge to translating its use from preclinical to clinical settings. Here, we review modern advancements in phage-based antimicrobial therapy and discuss the in vivo pharmacokinetics and biodistribution of phage, addressing critical challenges in their application that must be overcome for successful clinical implementation.

Resistance Gene Association and Inference Network (ReGAIN): A Bioinformatics Pipeline for Assessing Probabilistic Co-Occurrence Between Resistance Genes in Bacterial Pathogens

The rampant rise of multidrug resistant (MDR) bacterial pathogens poses a severe health threat, necessitating innovative tools to unravel the complex genetic underpinnings of antimicrobial resistance. Despite significant strides in developing genomic tools for detecting resistance genes, a gap remains in analyzing organism-specific patterns of resistance gene co-occurrence. Addressing this deficiency, we developed the Resistance Gene Association and Inference Network (ReGAIN), a novel web-based and command line genomic platform that uses Bayesian network structure learning to identify and map resistance gene networks in bacterial pathogens. ReGAIN not only detects resistance genes using well-established methods, but also elucidates their complex interplay, critical for understanding MDR phenotypes. Focusing on ESKAPE pathogens, ReGAIN yielded a queryable database for investigating resistance gene co-occurrence, enriching resistome analyses, and providing new insights into the dynamics of antimicrobial resistance. Furthermore, the versatility of ReGAIN extends beyond antibiotic resistance genes to include assessment of co-occurrence patterns among heavy metal resistance and virulence determinants, providing a comprehensive overview of key gene relationships impacting both disease progression and treatment outcomes.

Phenotypic and genomic insights into the pathogenicity and antimicrobial resistance of an Enterobacter roggenkampii strain isolated from diseased silver arowana (Osteoglossum bicirrhosum)

Enterobacter roggenkampii is an opportunistic pathogen that causes infections in a wide range of hosts. A bacterial strain named EOBSR_19 was isolated from diseased silver arowana, Osteoglossum bicirrhosum. This bacterium was identified as E. roggenkampii based on the phenotypic characteristics and sequence analysis of the16S rDNA and gyrB genes. Average nucleotide identity and phylogenetic analysis based on the whole genome sequence further confirmed the bacterial taxonomy of EOBSR_19. Artificial experimental infection indicated that EOBSR_19 was pathogenic to fish. Antimicrobial susceptibility test showed it was multi-drug resistant. The EOBSR_19 was found to be resistant to 18 antibiotics belonging to quinolones, macrolides, sulfonamides, aminoglycosides, and β-lactams classes. The whole genome sequencing analysis showed that EOBSR_19 carried 730 virulence genes that were annotated for different functional modules, such as adhesion and invasion, secretion system, siderophore transport system and bacterial toxin. Among them, the virulence genes related to adhesion and invasion were the most abundant. In addition, drug resistance genes involved in multiple mechanisms of antimicrobial resistance were identified in its genomics, including multidrug resistance efflux pumps, antibiotic inactivating enzymes, and antibiotic binding site mutations. Its genomic analysis via whole-genome sequencing provided insights into the pathogenicity and antimicrobial resistance.

Role of small molecules and nanoparticles in effective inhibition of microbial biofilms: A ray of hope in combating microbial resistance

Microbial biofilms pose a severe threat to global health, as they are associated with deadly chronic infections and antibiotic resistance. To date, very few drugs are in clinical practice that specifically target microbial biofilms. Therefore, there is an urgent need for the development of novel therapeutic options targeting biofilm-related infections. In this review, we discuss nearly seventy-five different molecular scaffolds published over the last decade (2010-2023) which have exhibited their biofilm inhibition potential. For convenience, we have classified these into five different sub-groups based on their origin and design (excluding peptides as they are placed in between small molecules and biologics), namely, heterocycles; inorganic small molecules & metal complexes; small molecules decorated nanoparticles; small molecules derived from natural products (both plant and marine sources); and small molecules designed by in-silico approach. These antibiofilm agents are capable of disrupting microbial biofilms and can offer a promising avenue for future developments in human medicine. A hitherto review of this kind will lay a platform for the researchers to find new molecular entities to curb the serious menace of antimicrobial resistance especially caused by biofilms.

Antimicrobial Resistance and the Prevalence of the Panton-Valentine Leukocidin Gene among Clinical Isolates of Staphylococcus aureus in Lithuania

This study aimed to determine resistance to antimicrobials of Staphylococcus aureus strains isolated from clinical specimens in Lithuanian hospitals and to identify the genes conferring resistance and virulence. The study was carried out from June 2019 to September 2021. S. aureus strains were isolated from skin, soft tissues, blood, lower respiratory tract, urine and other specimens. Antibiotic susceptibility testing was performed using the disc diffusion method according to EUCAST guidelines. All isolates were analyzed for detection of the ermA, ermC, mecA, mecC, tetK, tetM, and lukF-PV genes by multiplex real-time PCR. The 16S rRNA coding sequence was applied as an internal PCR control. Altogether, 745 S. aureus strains were analyzed. Antimicrobial susceptibility testing revealed that all isolates were susceptible to rifampin and vancomycin. Of the 745 strains, 94.8% were susceptible to tetracycline, 94.5% to clindamycin, and 88.3% to erythromycin. The lowest susceptibility rate was found for penicillin (25.8%). Six percent of the tested strains were methicillin-resistant S. aureus (MRSA). The majority of methicillin-resistant strains were isolated from skin and soft tissues (73.3%), with a smaller portion isolated from blood (17.8%) and respiratory tract (8.9%). The ermC gene was detected in 41.1% of erythromycin-resistant S. aureus strains, whereas ermA was detected in 32.2% of erythromycin-resistant S. aureus strains. 69.2% of tetracycline-resistant S. aureus strains had tetK gene, and 28.2% had tetM gene. 7.3% of S. aureus isolates harbored lukF-PV gene. The frequency of the pvl gene detection was significantly higher in MRSA isolates than in methicillin-susceptible S. aureus isolates (p < 0.0001).

Antimicrobial potential, GCMS analysis and molecular docking studies of Coelogyne suaveolens extracts: Identification of bioactive compounds with mechanism of action

Coelogyne suaveolens has been used as a traditional medicine for many years, and its potential as a natural source of antibacterial agents is of great interest. This investigation aimed to identify the bioactive compounds in the plant extract and assess their antibacterial properties. To achieve this, we identified the bioactive compounds using Gas chromatography mass spectrometry (GCMS) analysis on the extract's ethyl acetate fraction and used the disc diffusion method to determine the antibacterial effect. Additionally, molecular docking were performed to predict the binding affinities of selected phytochemicals against specific proteins in order to identify the root cause of bacterial inhibition. Our results revealed that the extract exhibited significant antibacterial activity against Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, and Klebsiella pneumoniae, which are common and problematic pathogens. Furthermore, molecular docking studies identified eight best-selected compounds, of which {androstan-17-one, oxime, (5.alpha.)-}, diethofencarb, tetraconazole, {3,6-dimethyl-2,3,3a,4,5,7a-hexahydrobenzofuran}, and geranyl acetate showed a significant binding affinity with best binding interaction with the target enzymes. This suggests that binding to these specific proteins might lead to the mechanism of action of the evaluated antibacterial action. In conclusion, the present study contributes to the growing body of knowledge on natural antimicrobial agents and could have significant implications for the development of new and effective antibacterial agents.

A cryptic plasmid is among the most numerous genetic elements in the human gut

Plasmids are extrachromosomal genetic elements that often encode fitness-enhancing features. However, many bacteria carry "cryptic" plasmids that do not confer clear beneficial functions. We identified one such cryptic plasmid, pBI143, which is ubiquitous across industrialized gut microbiomes and is 14 times as numerous as crAssphage, currently established as the most abundant extrachromosomal genetic element in the human gut. The majority of mutations in pBI143 accumulate in specific positions across thousands of metagenomes, indicating strong purifying selection. pBI143 is monoclonal in most individuals, likely due to the priority effect of the version first acquired, often from one's mother. pBI143 can transfer between Bacteroidales, and although it does not appear to impact bacterial host fitness in vivo, it can transiently acquire additional genetic content. We identified important practical applications of pBI143, including its use in identifying human fecal contamination and its potential as an alternative approach to track human colonic inflammatory states.

Thiazolotriazoles As Anti-infectives: Design, Synthesis, Biological Evaluation and In Silico Studies

The rational design of novel thiazolo[2,3-c][1,2,4]triazole derivatives was carried out based on previously identified antitubercular hit molecule H127 for discovering potent compounds showing antimicrobial activity. The designed compounds were screened for their binding efficacies against the antibacterial drug target enoyl-[acyl-carrier-protein] reductase, followed by prediction of drug-likeness and ADME properties. The designed analogues were chemically synthesized, characterized by spectroscopic techniques, followed by evaluation of antimicrobial activity against bacterial and fungal strains, as well as antitubercular activity against M. tuberculosis and M. bovis strains. Among the synthesized compounds, five compounds, 10, 11, 35, 37 and 38, revealed antimicrobial activity, albeit with differential potency against various microbial strains. Compounds 10 and 37 were the most active against S. mutans (MIC: 8 μg/mL), while compounds 11 and 37 showed the highest activity against B. subtillis (MIC: 16 μg/mL), whereas compounds 10, 11 and 37 displayed activities against E. coli (MIC: 16 μg/mL). Meanwhile, compounds 10 and 35 depicted activities against S. typhi (MIC: 16 μg/mL) and compound 10 showed antifungal activity against C. albicans (MIC: 32 μg/mL). The current study has identified two broad-spectrum antibacterial hit compounds (10 and 37). Further structural investigation on these molecules is underway to enhance their potency.