Systematic review and meta-analysis of the epidemiology of vancomycin-resistance Staphylococcus aureus isolates

Asymmetric total synthesis of polycyclic xanthenes and discovery of a WalK activator active against MRSA

The development of new antibiotics continues to pose challenges, particularly considering the growing threat of multidrug-resistant Staphylococcus aureus. Structurally diverse natural products provide a promising source of antibiotics. Herein, we outline a concise approach for the collective asymmetric total synthesis of polycyclic xanthene myrtucommulone D and five related congeners. The strategy involves rapid assembly of the challenging benzopyrano[2,3-a]xanthene core, highly diastereoselective establishment of three contiguous stereocenters through a retro-hemiketalization/double Michael cascade reaction, and a Mitsunobu-mediated chiral resolution approach with high optical purity and broad substrate scope. Quantum mechanical calculations provide insight into stereoselective construction mechanism of the three contiguous stereocenters. Additionally, this work leads to the discovery of an antibacterial agent against both drug-sensitive and drug-resistant S. aureus. This compound operates through a unique mechanism that promotes bacterial autolysis by activating the two-component sensory histidine kinase WalK. Our research holds potential for future antibacterial drug development.

Global distribution of heterogeneous vancomycin-intermediate Staphylococcus aureus strains (1997-2021): a systematic review and meta-analysis

BACKGROUND

Heterogeneous vancomycin-intermediate Staphylococcus aureus is considered one of the main causes in treatment failure of vancomycin, which leads to poor clinical outcomes. Herein, we comprehensively evaluated characteristics such as global prevalence, trend, and genetic backgrounds of these strains.

METHODS

In this study, we conducted a meta-analysis based on PRISMA checklist 2020. In the beginning, global databases were searched to achieve the studies related to the prevalence of hVISA in clinical isolates of methicillin-resistant Staphylococcus aureus. After retrieving the eligible English studies, the prevalence of hVISA isolates and their trend changes were assessed using event rate with 95% confidence intervals.

RESULTS

In the present study, the prevalence of 114 801 MRSA isolates (of 124 studies) was 64%. According to our results, although the frequency of infection with hVISA is increasing in recent years, there is not a significant difference between Asian countries and Europe/America (6.1% vs. 6.8%). In addition, infection with hVISA bacteria was higher in bacteraemic patients than other infections (9.4% vs. 5.5%), which increases hospitalization, treatment costs, and mortality in these patients. Isolates harbouring SCCmec types II and III are most common genotypes in hVISA strains.

CONCLUSIONS

The prevalence of hVISA is increasing, which will reduce the effectiveness of vancomycin treatment in the coming years. The presence of hVISA stains in blood samples was higher than the other samples, which is threatening for bacteraemic patients. The results of the current study indicate a universal program to identify and control the spread of such strains in nosocomial infections.

Development of an ultrafast PCR to detect clinically relevant acquired vancomycin-resistance genes from cultured enterococci

BACKGROUND

VRE are increasingly described worldwide. Screening of hospitalized patients at risk for VRE carriage is mandatory to control their dissemination. Here, we have developed the Bfast [VRE Panel] PCR kit, a rapid and reliable quantitative PCR assay for detection of vanA, vanB, vanD and vanM genes, from solid and liquid cultures adaptable to classical and ultrafast real-time PCR platforms.

METHODS

Validation was carried out on 133 well characterized bacterial strains, including 108 enterococci of which 64 were VRE. Analytical performances were determined on the CFX96 Touch (Bio-Rad) and Chronos Dx (BforCure), an ultrafast qPCR machine. Widely used culture plates and broths for enterococci selection/growth were tested.

RESULTS

All targeted van alleles (A, B, D and M) were correctly detected without cross-reactivity with other van genes (C, E, G, L and N) and no interference with the different routinely used culture media. A specificity and sensitivity of 100% and 99.7%, respectively, were determined, with limits of detection ranging from 21 to 238 cfu/reaction depending on the targets. The Bfast [VRE Panel] PCR kit worked equally well on the CFX and Chronos Dx platforms, with differences in multiplexing capacities (five and four optical channels, respectively) and in turnaround time (45 and 16 minutes, respectively).

CONCLUSIONS

The Bfast [VRE Panel] PCR kit is robust, easy to use, rapid and easily implementable in clinical microbiology laboratories for ultra-rapid confirmation of the four main acquired van genes. Its features, especially on Chronos Dx, seem to be unmatched compared to other tools for screening of VRE.

Lead generation of UPPS inhibitors targeting MRSA: Using 3D-QSAR pharmacophore modeling, virtual screening, molecular docking, and molecular dynamic simulations

Undecaprenyl Pyrophosphate Synthase (UPPS) is a vital target enzyme in the early stages of bacterial cell wall biosynthesis. UPPS inhibitors have antibacterial activity against resistant strains such as MRSA and VRE. In this study, we used several consecutive computer-based protocols to identify novel UPPS inhibitors. The 3D QSAR pharmacophore model generation (HypoGen algorithm) protocol was used to generate a valid predictive pharmacophore model using a set of UPPS inhibitors with known reported activity. The developed model consists of four pharmacophoric features: one hydrogen bond acceptor, two hydrophobic, and one aromatic ring. It had a correlation coefficient of 0.86 and a null cost difference of 191.39, reflecting its high predictive power. Hypo1 was proven to be statistically significant using Fischer's randomization at a 95% confidence level. The validated pharmacophore model was used for the virtual screening of several databases. The resulting hits were filtered using SMART and Lipinski filters. The hits were docked into the binding site of the UPPS protein, affording 70 hits with higher docking affinities than the reference compound (6TC, - 21.17 kcal/mol). The top five hits were selected through extensive docking analysis and visual inspection based on docking affinities, fit values, and key residue interactions with the UPPS receptor. Moreover, molecular dynamic simulations of the top hits were performed to confirm the stability of the protein-ligand complexes, yielding five promising novel UPPS inhibitors.

Ribosome Profiling Methods Adapted to the Study of RNA-Dependent Translation Regulation in Staphylococcus aureus

Noncoding RNAs, including regulatory RNAs (sRNAs), are instrumental in regulating gene expression in pathogenic bacteria, allowing them to adapt to various stresses encountered in their host environments. Staphylococcus aureus is a well-studied model for RNA-mediated regulation of virulence and pathogenicity, with sRNAs playing significant roles in shaping S. aureus interactions with human and animal hosts. By modulating the translation and/or stability of target mRNAs, sRNAs regulate the synthesis of virulence factors and regulatory proteins required for pathogenesis. Moreover, perturbation of the levels of RNA modifications in two other classes of noncoding RNAs, rRNAs, and tRNAs, has been proposed to contribute to stress adaptation. However, the study of how these various factors affect translation regulation has often been restricted to specific genes, using in vivo reporters and/or in vitro translation systems. Genome-wide sequencing approaches offer novel perspectives for studying RNA-dependent regulation. In particular, ribosome profiling methods provide a powerful resource for characterizing the overall landscape of translational regulation, contributing to a better understanding of S. aureus physiopathology. Here, we describe protocols that we have adapted to perform ribosome profiling in S. aureus.

Pinus koraiensis Essential Oil Attenuates the Pathogenicity of Superbacteria by Suppressing Virulence Gene Expression

In the quest to combat infections attributable to antibiotic-resistant superbacteria, an essential oil derived from the needles of Pinus koraiensis Sieb. et Zucc. (PKEO) has emerged as a promising solution. In this study, we demonstrate that PKEO can be used to inhibit the growth, glucose metabolite acidogenicity, and biofilm formation of methicillin-resistant Staphylococcus aureus (MRSA). Quantitative PCR analysis provided direct evidence that PKEO reduces the mRNA expression of the accessory gene regulator A (agrA) and staphylococcal accessory regulator A (sarA), thereby indicating its inhibitory effect on pathogenic regulatory genes. Chromatographic analyses of PKEO identified terpene hydrocarbons as prominent essential oil constituents. These compounds, notably α-pinene, limonene, and β-caryophyllene, have been established to have antimicrobial properties. Our findings indicate that an oil derived from P. koraiensis can effectively combat antibiotic-resistant strains by disrupting the pathogenicity regulatory system, thereby establishing PKEO as a promising candidate for the treatment of MRSA infections.

Molecular Epidemiology of Methicillin-Resistant Staphylococcus aureus among Patients Diagnosed with Surgical Site Infection at Four Hospitals in Ethiopia

Methicillin-resistant Staphylococcus aureus (MRSA) is a common cause of severe surgical site infections (SSI). The molecular epidemiology of MRSA is poorly documented in Ethiopia. This study is designed to determine the prevalence of MRSA and associated factors among patients diagnosed with SSI. A multicenter study was conducted at four hospitals in Ethiopia. A wound culture was performed among 752 SSI patients. This study isolated S. aureus and identified MRSA using standard bacteriology, Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS), and cefoxitin disk diffusion test. The genes mecA, femA, vanA, and vanB were detected through PCR tests. S. aureus was identified in 21.6% of participants, with 24.5% of these being methicillin-resistant Staphylococci and 0.6% showing vancomycin resistance. Using MALDI-TOF MS for the 40 methicillin-resistant Staphylococci, we confirmed that 31 (77.5%) were S. aureus, 6 (15%) were Mammaliicoccus sciuri, and the other 3 (2.5%) were Staphylococcus warneri, Staphylococcus epidermidis, and Staphylococcus haemolyticus. The gene mecA was detected from 27.5% (11/40) of Staphylococci through PCR. Only 36.4% (4/11) were detected in S. aureus, and no vanA or vanB genes were identified. Out of 11 mecA-gene-positive Staphylococci, 8 (72.7%) were detected in Debre Tabor Comprehensive Specialized Hospital. Methicillin-resistant staphylococcal infections were associated with the following risk factors: age ≥ 61 years, prolonged duration of hospital stay, and history of previous antibiotic use, p-values < 0.05. Hospitals should strengthen infection prevention and control strategies and start antimicrobial stewardship programs.

Epidemiology of Antimicrobial Resistance Genes in Staphylococcus aureus Isolates from a Public Database from a One Health Perspective-Sample Origin and Geographical Distribution of Isolates

Staphylococcus aureus are commensal bacteria that are found in food, water, and a variety of settings in addition to being present on the skin and mucosae of both humans and animals. They are regarded as a significant pathogen as well, with a high morbidity that can cause a variety of illnesses. The Centers for Disease Control and Prevention (CDC) has listed them among the most virulent and resistant to antibiotics bacterial pathogens, along with Escherichia coli, Staphylococcus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterococcus faecalis, and Enterococcus faecium. Additionally, S. aureus is a part of the global threat posed by the existence of antimicrobial resistance (AMR). Using 26,430 S. aureus isolates from a global public database (NPDIB; NCBI Pathogen Detection Isolate Browser), epidemiological research was conducted. The results corroborate the evidence of notable variations in isolate distribution and ARG (Antimicrobial Resistance Gene) clusters between isolate sources and geographic origins. Furthermore, a link between the isolates from human and animal populations is suggested by the ARG cluster patterns. This result and the widespread dissemination of the pathogens among animal and human populations highlight how crucial it is to learn more about the epidemiology of these antibiotic-resistance-related infections using a One Health approach.

Preparation, Physicochemical Characterization, Antimicrobial Effects, Biocompatibility and Cytotoxicity of Co-Loaded Meropenem and Vancomycin in Mesoporous Silica Nanoparticles

Mesoporous silica nanoparticles (MSNPs) have been reported as an effective system to co-deliver a variety of different agents to enhance efficiency and improve biocompatibility. This study was aimed at the preparation, physicochemical characterization, antimicrobial effects, biocompatibility, and cytotoxicity of vancomycin and meropenem co-loaded in the mesoporous silica nanoparticles (Van/Mrp-MSNPs). The prepared nanoparticles were explored for their physicochemical features, antibacterial and antibiofilm effects, biocompatibility, and cytotoxicity. The minimum inhibitory concentrations (MICs) of the Van/Mrp-MSNPs (0.12-1 µg/mL) against Staphylococcus aureus isolates were observed to be lower than those of the same concentrations of vancomycin and meropenem. The minimum biofilm inhibitory concentration (MBIC) range of the Van/Mrp-MSNPs was 8-64 μg/mL, which was lower than the meropenem and vancomycin MBICs. The bacterial adherence was not significantly decreased upon exposure to levels lower than the MICs of the MSNPs and Van/Mrp-MSNPs. The viability of NIH/3T3 cells treated with serial concentrations of the MSNPs and Van/Mrp-MSNPs were 73-88% and 74-90%, respectively. The Van/Mrp-MSNPs displayed considerable inhibitory effects against MRSA, favorable biocompatibility, and low cytotoxicity. The Van/Mrp-MSNPs could be a potential system for the treatment of infections.

Teicoplanin associated gene tcaA inactivation increases persister cell formation in Staphylococcus aureus

Staphylococcus aureus is part of normal human flora and is widely associated with hospital-acquired bacteremia. S. aureus has shown a diverse array of resistance to environmental stresses and antibiotics. Methicillin-resistant S. aureus (MRSA) is on the high priority list of new antibiotics discovery and glycopeptides are considered the last drug of choice against MRSA. S. aureus has developed resistance against glycopeptides and the emergence of vancomycin-intermediate-resistant, vancomycin-resistant, and teicoplanin-resistant strains is globally reported. Teicoplanin-associated genes tcaR-tcaA-tcaB (tcaRAB) is known as the S. aureus glycopeptide resistance operon that is associated with glycopeptide resistance. Here, for the first time, the role of tcaRAB in S. aureus persister cells formation, and ΔtcaA dependent persisters' ability to resuscitate the bacterial population was explored. We recovered a clinical strain of MRSA from a COVID-19 patient which showed a high level of resistance to teicoplanin, vancomycin, and methicillin. Whole genome RNA sequencing revealed that the tcaRAB operon expression was altered followed by high expression of glyS and sgtB. The RNA-seq data revealed a significant decrease in tcaA (p = 0.008) and tcaB (p = 0.04) expression while tcaR was not significantly altered. We knocked down tcaA, tcaB, and tcaR using CRISPR-dCas9 and the results showed that when tcaA was suppressed by dCas9, a significant increase was witnessed in persister cells while tcaB suppression did not induce persistence. The results were further evaluated by creating a tcaA mutant that showed ΔtcaA formed a significant increase in persisters in comparison to the wild type. Based on our findings, we concluded that tcaA is the gene that increases persister cells and glycopeptide resistance and could be a potential therapeutic target in S. aureus.

Virtual screening and molecular dynamics simulation study of abyssomicins as potential inhibitors of COVID-19 virus main protease and spike protein

The lack of any effective cure for the infectious COVID-19 disease has created a sense of urgency and motivated the search for effective antiviral drugs. Abyssomicins are actinomyces-derived spirotetronates polyketides antibiotics known for their promising antibacterial, antitumor, and antiviral activities. In this study, computational approaches were used to investigate the binding mechanism and the inhibitory ability of 38 abyssomicins against the main protease (Mpro) and the spike protein receptor-binding domain (RBD) of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). The results identified abyssomicins C, J, W, atrop-O-benzyl abyssomicin C, and atrop-O-benzyl desmethyl abyssomicin C as the most potential inhibitors of Mpro and RBD with binding energy ranges between -8.1 and -9.9 kcal mol-1; and between -6.9 and -8.2 kcal mol-1, respectively. Further analyses of physicochemical properties and drug-likeness suggested that all selected active abyssomicins, with the exception of abyssomicin J, obeyed Lipinski's rule of five. The stability of protein-ligand complexes was confirmed by performing molecular dynamics simulation for 100 ns and evaluating parameters such as such as root mean square deviation (RMSD), root mean square fluctuation (RMSF), radius of gyration (Rg), solvent accessible surface area (SASA), total number of contacts, and secondary structure. Prime/MM-GBSA (Molecular Mechanics-General Born Surface Area) and principal component analysis (PCA) analyses also confirmed the stable nature of protein-ligand complexes. Overall, the results showed that the studied abyssomicins have significant interactions with the selected protein targets; therefore, they were deemed viable candidates for further in vitro and in vivo evaluation.Communicated by Ramaswamy H. Sarma.

Antimicrobial Resistance Patterns of Staphylococcus aureus and Enterococcus Species at the Ethiopian Public Health Institute, Ethiopia: A Five-Year Retrospective Analysis

Purpose

The study aimed to investigate the antimicrobial resistance patterns of Staphylococcus aureus and Enterococcus species isolated from clinical specimens over a period of five years, including resistance to methicillin and vancomycin.

Patients and Methods

Bacterial identification and antimicrobial susceptibility testing reports from 2017 to 2021 at the Ethiopian Public Health Institute were used for this retrospective study. The organisms were identified using either BD Phoenix M50, Vitek 2 compact, or conventional biochemical methods, whichever was available at the time of testing. The antimicrobial susceptibility profiles of the isolates were determined using either Kirby-Bauer disc diffusion, BD phoenix M50, or Vitek 2 compact. WHONET software was used to analyze the antimicrobial resistance patterns of both organisms. The p-values of ≤0.05 were considered statistically significant.

Results

During the study period, a total of 315 Staphylococcus aureus and 92 Enterococcus species were isolated. Out of 315 Staphylococcus aureus isolates, 27% and 5.1% were methicillin and vancomycin resistant, respectively. Staphylococcus aureus showed very high resistance to Penicillin G (86.7%). Out of 92 Enterococcus species recovered, 8.7% were vancomycin-resistant. Enterococcus species showed very high resistance to Penicillin G (71.4%) and tetracyclines (83.3%). Methicillin-resistant Staphylococcus aureus shows 100% resistance to penicillin followed by ciprofloxacin (50%), erythromycin (45.6%), and tetracycline (44.2%) and lower resistance to vancomycin (18.8%). All vancomycin-resistant isolates of both organisms were fully resistant (100%) to all antibiotics tested, except for linezolid and daptomycin, to which they were susceptible.

Conclusion

This study found a high prevalence of methicillin and vancomycin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus species between 2017 and 2021. However, there were no statistically significant changes in the prevalence of these organisms during the study period. This suggests that larger and more representative nationwide data is needed to show trends of these pathogens.

Antibiotic Resistance: Challenges and Strategies in Combating Infections

From a broader perspective, antibiotic or antimicrobial resistance is still evolving and spreading internationally. Infectious diseases have become more complex and often impossible to cure, increasing morbidity and mortality. Despite the failure of conventional, standard antimicrobial therapy, no new class of antibiotics has been developed in the last 20 years, which results in various cutting-edge and other tactics that can be used to encounter these disease-causing microorganisms with antibiotic resistance. In the continued fight against bacterial infections, there is an urgent requirement for new antibiotics and other antimicrobials. Antibiotic resistance is inevitable, and pharmaceutical companies consistently show little interest in funding novel antibiotic research. Some methods are being used as a possible replacement for conventional antibiotics. Combination therapy, methods that target the proteins or enzymes that cause antimicrobial resistance and bacterial resistance, systems for delivery of the drug, physicochemical approaches, and informal ways, such as the CRISPR-Cas system, are some of these approaches. These various approaches influence how multi-drug-resistant organisms are handled in human clinical settings.

The prevalence of vancomycin-resistant Staphylococcus aureus in Ethiopia: a systematic review and meta-analysis

INTRODUCTION

Vancomycin-resistant Staphylococcus aureus, identified as a "high priority antibiotic-resistant pathogen" by the World Health Organization, poses a significant threat to human health. This systematic review and meta-analysis aimed to estimate the pooled prevalence of vancomycin-resistant Staphylococcus aureus in Ethiopia.

METHODS

This systematic review and meta-analysis was reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Studies that reported VRSA prevalence due to infection or carriage from human clinical specimens were extensively searched in bibliographic databases and grey literatures using entry terms and combination key words. Electronic databases like PubMed, Google Scholar, Wiley Online Library, African Journal Online, Scopus, Science Direct, Embase, and ResearchGate were used to find relevant articles. In addition, the Joanna Briggs Institute quality appraisal tool was used to assess the quality of the included studies. Stata version 14 software was used for statistical analysis. Forest plots using the random-effect model were used to compute the overall pooled prevalence of VRSA and for the subgroup analysis. Heterogeneity was assessed using Cochrane chi-square (I2) statistics. After publication bias was assessed using a funnel plot and Egger's test, trim & fill analysis was carried out. Furthermore, sensitivity analysis was done to assess the impact of a single study on pooled effect size.

RESULTS

Of the 735 studies identified, 31 studies that fulfilled the eligibility criteria were included for meta-analysis consisted of 14,966 study participants and 2,348 S. aureus isolates. The overall pooled prevalence of VRSA was 14.52% (95% CI: 11.59, 17.44). Significantly high level of heterogeneity was observed among studies (I2 = 93.0%, p < 0.001). The region-based subgroup analysis depicted highest pooled prevalence of 47.74% (95% CI: 17.79, 77.69) in Sidama region, followed by 14.82% (95% CI: 8.68, 19.88) in Amhara region, while Oromia region had the least pooled prevalence 8.07% (95% CI: 4.09, 12.06). The subgroup analysis based on AST methods depicted a significant variation in pooled prevalence of VRSA (6.3% (95% CI: 3.14, 9.43) for MIC-based methods, and 18.4% (95% CI: 14.03, 22.79) for disk diffusion AST method) which clearly showed that disk diffusion AST method overestimates the pooled VRSA prevalence. The total number of S. aureus isolates was found to be the responsible variable for the existence of heterogeneity among studies (p = 0.033).

CONCLUSION

This study showed an alarmingly high pooled prevalence of VRSA necessitating routine screening, appropriate antibiotic usage, and robust infection prevention measures to manage MRSA infections and control the emergence of drug resistance. Furthermore, mainly attributable to the overestimation of VRSA burden while using disk diffusion method, there is an urgent need to improve the methods to determine vancomycin resistance in Ethiopia and incorporate MIC-based VRSA detection methods in routine clinical laboratory tests, and efforts should be directed at improving it nationally.

TRIAL REGISTRATION

PROSPERO registration identification number: CRD42023422043.

Analysis on Bacterial Distribution and Change of Drug Resistance Rate in ICUs Across Southwest China from 2018 to 2022

Purpose

To analyze the distribution of bacteria and their drug resistance changes in Intensive Care Units (ICUs) across Southwest China from 2018 to 2022 and establish the antibiogram in this region to provide a basis for early empirical antimicrobial use.

Methods

Non-repetitive pathogens isolated from 109 member units with qualified data were obtained from the Antimicrobial Resistance Surveillance System in Sichuan Province, southwest China. The results obtained were interpreted with reference to CLSI M100-31th, and analyzed with WHONET 5.6 software.

Results

A total of 46,728 clinical isolates in ICUs were collected from 2018 to 2022, of which gram-negative organisms accounted for 76.1%, and gram-positive were 23.9%. The top 5 were Klebsiella pneumoniae, Acinetobacter baumannii, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus, respectively. From 2018 to 2022, the resistance rates of Klebsiella pneumoniae to imipenem and meropenem changed from 14.5% and 17.8% to 14.0% and 14.4%, showing a steady downward trend. Escherichia coli was always highly sensitive to carbapenems, with a total resistance rate of 3.8%. Among non-fermented gram-negative bacteria, the resistance rates of Pseudomonas aeruginosa to imipenem and meropenem decreased significantly, changed from 25.3% and 22.9% in 2018 to 20.0% and 15.1% in 2022. However, Acinetobacter baumannii showed high resistance rates of 76.2% and 76.9% to imipenem and meropenem, respectively. MRSA and MRCNS accounted for 31.7% and 82.7%, respectively. No vancomycin and linezolid-resistant Staphylococcus aureus was isolated. Enterococcus faecalis maintained high activity to vancomycin, teicoplanin, and linezolid; no vancomycin or teicoplanin-resistant Enterococcus faecium strains were detected.

Conclusion

From 2018 to 2022, the isolated bacteria in ICU were mainly gram-negative bacteria, and the growth of some multidrug-resistant bacteria was effectively controlled. All levels of medical institutions should continue to strengthen bacterial resistance surveillance, promote the establishment of antimicrobial stewardship program, and enhance restrictions on outpatient antimicrobial use.

Staphylococcus aureus Induced Wound Infections Which Antimicrobial Resistance, Methicillin- and Vancomycin-Resistant: Assessment of Emergence and Cross Sectional Study

Background

Wound infection is a prevalent concern in the medical field, being is a multi-step process involving several biological processes. Methicillin-resistant S. aureus (MRSA) and vancomycin-resistant S. aureus (VRSA) infections often occur in areas of damaged skin, such as abrasions and open wounds.

Methods

This research aims to light the incidence of MRSA and VRSA in wound swabs, the antimicrobial susceptibility configuration of isolated S. aureus patterns in pus/wound samples collected from Saudi Arabian tertiary hospital. The cross section study, β- lactamase detection, VRSA genotyping, MAR index, D-test and VRSA genotyping are methods, which used for completed this research.

Results

Patients of several ages and genders delivered specimens from two hospitals in the Al jouf area, in the northern province of Saudi Arabia. S. aureus was found in 188 (34.7%) of the 542 wounds. The traumatized wounds provided 71 isolates (38.8%), surgical wound provided 49 isolates (26.8%) and abscess were represented 16 by isolates (8.7%). In the study, 123 (65.4%) out of 188 were MRSA, 60 (31.9%) were MSSA, and five (2.7%) were VRSA. Linezolid and rifampin were found to be the most effective antimicrobials with 100% in vitro antibacterial activity against S. aureus isolates. The Multiple antimicrobials resistance (MAR) index revealed 73 isolates (38.9%) with a MAR index greater than 0.2, and 115 (61.1%) less than 0.2. The D-test showed that of MLSb phenotypes among S. aureus, 22 (11.7%) strains were D-test positive (MLSbi phenotype), 53 (28.2%) strains were constitutive MLSc phenotypes, and 17 (9%) strains were shown to have MSb phenotypes. All VRSA isolates (n=5) were found to be positive for vanA, and no vanB positive isolates were detected in the study.

Conclusion

Regular monitoring and an antimicrobials stewardship program should be in place to provide critical information that can be utilized for empirical therapy and future prevention strategies.

Epidemiology of Antimicrobial Resistance Genes in Staphyloccocus aureus Isolates from a Public Database in a One Health Perspective-Sample Characteristics and Isolates' Sources

Staphylococcus aureus is considered one of the most widespread bacterial pathogens for both animals and humans, being the causative agent of various diseases like food poisoning, respiratory tract infections, nosocomial bacteremia, and surgical site and cardiovascular infections in humans, as well as clinical and subclinical mastitis, dermatitis, and suppurative infections in animals. Thanks to their genetic flexibility, several virulent and drug-resistant strains have evolved mainly due to horizontal gene transfer and insurgence of point mutations. Infections caused by the colonization of such strains are particularly problematic due to frequently occurring antibiotic resistance, particulary methicillin-resistant S. aureus (MRSA), and are characterized by increased mortality, morbidity, and hospitalization rates compared to those caused by methicillin-sensitive S. aureus (MSSA). S. aureus infections in humans and animals are a prime example of a disease that may be managed by a One Health strategy. In fact, S. aureus is a significant target for control efforts due to its zoonotic potential, the frequency of its illnesses in both humans and animals, and the threat posed by S. aureus antibiotic resistance globally. The results of an epidemiological analysis on a worldwide public database (NCBI Pathogen Detection Isolate Browser; NPDIB) of 35,026 S. aureus isolates were described. We considered the diffusion of antibiotic resistance genes (ARGs), in both human and animal setting, and the results may be considered alarming. The result of this study allowed us to identify the presence of clusters with specific ARG patterns, and that these clusters are associated with different sources of isolation (e.g., human, non-human).

The Epidemiology of Animal-Associated Methicillin-Resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) remains an important etiological factor of human and animal infectious diseases, causing significant economic losses not only in human healthcare but also in the large-scale farming sector. The constantly changing epidemiology of MRSA observed globally affects animal welfare and raises concerns for public health. High MRSA colonization rates in livestock raise questions about the meaning of reservoirs and possible transmission pathways, while the prevalence of MRSA colonization and infection rates among companion animals vary and might affect human health in multiple ways. We present the main findings concerning the circulation of animal-associated MRSA (AA-MRSA) in the environment and factors influencing the direction, mechanisms, and routes of its transmission. Studies have shown it that S. aureus is a multi-host bacterial pathogen; however, its adaptation mechanisms enabling it to colonize and infect both animal and human hosts are still rarely discussed. Finally, we elaborate on the most successful strategies and programs applied limiting the circulation of AA-MRSA among animals and humans. Although MRSA strains colonizing animals rarely infect humans, they undergo host-adaptive evolution enabling them to spread and persist in human populations.

Simulation of optimal dose regimens of photoactivated curcumin for antimicrobial resistance pneumonia in COVID-19 patients: A modeling approach

Background

Secondary antimicrobial resistance bacterial (AMR) pneumonia could lead to an increase in mortality in COVID-19 patients, particularly of geriatric patients with underlying diseases. The comedication of current medicines for AMR pneumonia with corticosteroids may lead to suboptimal treatment or toxicities due to drug-drug interactions (DDIs).

Objective

This study aimed to propose new promising dosage regimens of photoactivated curcumin when co-administered with corticosteroids for the treatment of antimicrobial resistance (AMR) pneumonia in COVID-19 patients.

Methods

A whole-body physiologically-based pharmacokinetic (PBPK) with the simplified lung compartments model was built and verified following standard model verification (absolute average-folding error or AAFEs). The pharmacokinetic properties of photoactivated were assumed to be similar to curcumin due to minor changes in physiochemical properties of compound by photoactivation. The acceptable AAFEs values were within 2-fold. The verified model was used to simulate new regimens for different formulations of photoactivated curcumin.

Results

The AAFEs was 1.12-fold. Original formulation (120 mg once-daily dose) or new intramuscular nano-formulation (100 mg with a release rate of 10/h given every 7 days) is suitable for outpatients with MRSA pneumonia to improve patient adherence. New intravenous formulation (2000 mg twice-daily doses) is for hospitalized patients with both MRSA and VRSA pneumonia.

Conclusion

The PBPK models, in conjunction with MIC and applied physiological changes in COVID-19 patients, is a potential tool to predict optimal dosage regimens of photoactivated curcumin for the treatment of co-infected AMR pneumonia in COVID-19 patients. Each formulation is appropriate for different patient conditions and pathogens.

Epidemiology of Staphylococcus aureus Non-Susceptible to Vancomycin in South Asia

Staphylococcus aureus is one of the ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) pathogens among which multidrug resistance has emerged. Resistance to methicillin has resulted in clinicians using the antibiotic of last resort, vancomycin, to treat infections caused by methicillin-resistant S. aureus (MRSA). However, excessive use and misuse of vancomycin are major causes of resistance among S. aureus strains. South Asia encompasses ~25% of the world's population, and countries in South Asia are often characterized as low- and middle-income with poor healthcare infrastructure that may contribute to the emergence of antibiotic resistance. Here, we briefly highlight the mechanism of vancomycin resistance, its emergence in S. aureus, and the molecular epidemiology of non-susceptible S. aureus to vancomycin in the South Asian region.

Progress in the Prevalence, Classification and Drug Resistance Mechanisms of Methicillin-Resistant Staphylococcus aureus

Staphylococcus aureus is a common human pathogen with a variety of virulence factors, which can cause multiple infectious diseases. In recent decades, due to the constant evolution and the abuse of antibiotics, Staphylococcus aureus was becoming more resistant, the infection rate of MRSA remained high, and clinical treatment of MRSA became more difficult. The genetic diversity of MRSA was mainly represented by the continuous emergence of epidemic strains, resulting in the constant changes of epidemic clones. Different classes of MRSA resulted in different epidemics and resistance characteristics, which could affect the clinical symptoms and treatments. MRSA had also spread from traditional hospitals to community and livestock environments, and the new clones established a relationship between animals and humans, promoting further evolution of MRSA. Since the resistance mechanism of MRSA is very complex, it is important to clarify these resistance mechanisms at the molecular level for the treatment of infectious diseases. We firstly described the diversity of SCCmec elements, and discussed the types of SCCmec, its drug resistance mechanisms and expression regulations. Then, we described how the vanA operon makes Staphylococcus aureus resistant to vancomycin and its expression regulation. Finally, a brief introduction was given to the drug resistance mechanisms of biofilms and efflux pump systems. Analyzing the resistance mechanism of MRSA can help study new anti-infective drugs and alleviate the evolution of MRSA. At the end of the review, we summarized the treatment strategies for MRSA infection, including antibiotics, anti-biofilm agents and efflux pump inhibitors. To sum up, here we reviewed the epidemic characteristics of Staphylococcus aureus, summarized its classifications, drug resistance mechanisms of MRSA (SCCmec element, vanA operon, biofilm and active efflux pump system) and novel therapy strategies, so as to provide a theoretical basis for the treatment of MRSA infection.

Antibiotic resistance profiling and valorization of food waste streams to starter culture biomass and exopolysaccharides through fed-batch fermentations

The present study evaluated antibiotic resistance (ABR) in bacteria isolated from different food wastes viz., meat slaughterhouses, dairy and restaurants. About 120 strains isolated from the food waste were subjected to ABR screening. More than 50% of all the strains were resistant to Vancomycin, Neomycin and Methicilin, which belong to third-generation antibiotics. Two lactic acid bacteria (LAB) free of ABR were chosen to be used as starter cultures in media formulated from food waste. Food waste combination (FWC-4) was found to be on par with the nutrient broth in biomass production. The non-ABR LAB strains showed excellent probiotic properties, and in the fed-batch fermentation process, adding a nitrogen source (soya protein) enhanced the microbial biomass (3.7 g/l). Additionally, exopolysaccharide production was found to be 2.3 g/l. This study highlights the ABR incidence in food waste medium and its economic advantage for starter culture biomass production.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-022-01222-9.

Escalation of antimicrobial resistance among MRSA part 2: focus on infections and treatment

INTRODUCTION

MRSA is associated with causing a variety of infections including skin and skin structure infections, catheter and device-related (e.g. central venous catheter, prosthetic heart valve) infections, infectious endocarditis, blood stream infections, bone, and joint infections (e.g. osteomyelitis, prosthetic joint, surgical site), central nervous system infections (e.g. meningitis, brain/spinal cord abscess, ventriculitis, hydrocephalus), respiratory tract infections (e.g. hospital-acquired pneumonia, ventilator-associated pneumonia), urinary tract infections, and gastrointestinal infections. The emergence and spread of multidrug resistant (MDR) MRSA clones has limited therapeutic options. Older agents such as vancomycin, linezolid and daptomycin and a variety of newer MRSA antimicrobials and combination therapy are available to treat serious MRSA infections.

AREAS COVERED

The authors discuss infections caused by MRSA as well as common older and newer antimicrobials and combination therapy for MRSA infections. A literature search of MRSA was performed via PubMed (up to September 2022), using the keywords: antimicrobial resistance; β-lactams; multidrug resistance, Staphylococcus aureus, vancomycin; glycolipopeptides.

EXPERT OPINION

Innovation, discovery, and development of new and novel classes of antimicrobial agents are critical to expand effective therapeutic options. The authors encourage the judicious use of antimicrobials in accordance with antimicrobial stewardship programs along with infection-control measures to minimize the spread of MRSA.

Therapeutic Options and Outcomes for the Treatment of Children with Gram-Positive Bacteria with Resistances of Concern: A Systematic Review

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA), methicillin-resistant coagulase-negative Staphylococci (MR-CoNS), and vancomycin-resistant Enterococci (VRE) are increasing worldwide and represent a threat for the limited treatment options in pediatric patients and neonates compared to adults. Recommendations in pediatrics are mainly extrapolated from adults' studies.

METHODS

A literature search for the treatment of these pathogens in children (<18 years old) was conducted in Embase, MEDLINE, and Cochrane Library. Studies reporting data on single-patient-level outcomes related to a specific antibiotic treatment for multidrug resistant (MDR) Gram-positive bacterial infection in children were included. Studies reporting data from adults and children were included if single-pediatric-level information could be identified (PROSPERO registration: CRD42022383867).

RESULTS

The search identified 11,740 studies (since January 2000), of which 48 fulfilled both the inclusion and the exclusion criteria and were included in the analysis: 29 for MRSA, 20 for VRE, and seven for MR-CoNS. Most studies were retrospective studies. Vancomycin was mainly used as a comparator, while linezolid and daptomycin were the most studied antimicrobials showing good efficacy.

CONCLUSIONS

Linezolid showed a safety and efficacy profile in a neonatal setting; daptomycin is increasingly used for MRSA, but the evidence is scarce for VRE.

Evaluation of the Antibacterial Activity of Quinoxaline Derivative Compound Against Methicillin-Resistant Staphylococcus aureus

Background

While the frequency of methicillin-resistant Staphylococcus aureus (MRSA) continues to rise globally, there is a fear regarding an increase in vancomycin resistance among S. aureus strains. As far back as the 1960s, MRSA was one of the world's most prevalent antibiotic-resistant bacteria. Among hospitalized patients and community members, MRSA is the cause of a significant number of infections. As a result of its resistance to classical beta-lactam and, in some cases, vancomycin antibiotics, efforts must be made as soon as feasible to find a new approach to fighting MRSA.

Purpose

This study is designed to evaluate the antibacterial activity of quinoxaline derivative compound against MRSA in comparison with vancomycin as a reference drug.

Methods

Sixty MRSA isolates were subjected to susceptibility testing by broth microdilution method for quinoxaline derivative compound and vancomycin. Each drug's minimal inhibitory concentration (MIC) was determined and compared.

Results

Among the sixty MRSA isolates, most of the quinoxaline derivative compound MIC findings (56.7%) were 4 µg/mL compared to vancomycin MIC values (63.3%) of 4 µg/mL. In comparison, 20% of quinoxaline derivative compound MIC readings were 2 µg/mL, while the vancomycin MIC results were 6.7%. However, the overall proportion of MIC readings at ≤2 µg/mL for both antibacterial agents was equal (23.3%). None of the isolates were resistant to vancomycin.

Conclusion

This experiment revealed that most MRSA isolates were associated with low MICs (1-4 μg/mL) for quinoxaline derivative compound. Overall, the susceptibility of the quinoxaline derivative compound signifies a promising efficacy against MRSA and may set a novel treatment approach.

Structural basis of broad-spectrum β-lactam resistance in Staphylococcus aureus

Broad-spectrum β-lactam antibiotic resistance in Staphylococcus aureus is a global healthcare burden1,2. In clinical strains, resistance is largely controlled by BlaR13, a receptor that senses β-lactams through the acylation of its sensor domain, inducing transmembrane signalling and activation of the cytoplasmic-facing metalloprotease domain4. The metalloprotease domain has a role in BlaI derepression, inducing blaZ (β-lactamase PC1) and mecA (β-lactam-resistant cell-wall transpeptidase PBP2a) expression3-7. Here, overcoming hurdles in isolation, we show that BlaR1 cleaves BlaI directly, as necessary for inactivation, with no requirement for additional components as suggested previously8. Cryo-electron microscopy structures of BlaR1-the wild type and an autocleavage-deficient F284A mutant, with or without β-lactam-reveal a domain-swapped dimer that we suggest is critical to the stabilization of the signalling loops within. BlaR1 undergoes spontaneous autocleavage in cis between Ser283 and Phe284 and we describe the catalytic mechanism and specificity underlying the self and BlaI cleavage. The structures suggest that allosteric signalling emanates from β-lactam-induced exclusion of the prominent extracellular loop bound competitively in the sensor-domain active site, driving subsequent dynamic motions, including a shift in the sensor towards the membrane and accompanying changes in the zinc metalloprotease domain. We propose that this enhances the expulsion of autocleaved products from the active site, shifting the equilibrium to a state that is permissive of efficient BlaI cleavage. Collectively, this study provides a structure of a two-component signalling receptor that mediates action-in this case, antibiotic resistance-through the direct cleavage of a repressor.

Vancomycin Resistance in Enterococcus and Staphylococcus aureus

Enterococcus faecalis, Enterococcus faecium and Staphylococcus aureus are both common commensals and major opportunistic human pathogens. In recent decades, these bacteria have acquired broad resistance to several major classes of antibiotics, including commonly employed glycopeptides. Exemplified by resistance to vancomycin, glycopeptide resistance is mediated through intrinsic gene mutations, and/or transferrable van resistance gene cassette-carrying mobile genetic elements. Here, this review will discuss the epidemiology of vancomycin-resistant Enterococcus and S. aureus in healthcare, community, and agricultural settings, explore vancomycin resistance in the context of van and non-van mediated resistance development and provide insights into alternative therapeutic approaches aimed at treating drug-resistant Enterococcus and S. aureus infections.

Alhoot M, Abdul Karim S. Multidrug-Resistant Staphylococcus aureus as Coloniser in Healthy Individuals

Staphylococcus aureus is a common human pathogen that can cause mild superficial infections to deep-seated abscesses and sepsis. One of the characteristics of S. aureus is the ability to colonise healthy individuals while leaving them asymptomatic. These carriers’ risk harbouring an antibiotic-resistant strain that may be harmful to the individual and the community. S. aureus carriage in healthcare personnel is being studied extensively in many parts of the world. However, the relationship between colonisation and disease among those with no previous exposure to healthcare remains untouched. Colonisation of the nasal cavity and its surrounding by pathogenic organisms such as S. aureus leads to the increased risk of infection. Hospital-acquired infections associated with S. aureus infections are common and studies related to these types of infections among various study groups are largely documented. However, over the last decade, an increase in community-associated methicillin-resistant S. aureus has been noted, increasing the need to identify the prevalence of the organism among healthy individuals and assessing the antibiotic resistance patterns. Systemic surveillance of the community for colonisation of S. aureus and identifying the antibiotic-resistant pattern is critical to determine the appropriate empiric antibiotic treatment.

Conformationally restricted, dipeptide-based, self-assembled nanoparticles for efficient vancomycin delivery

Aim: Emergence of vancomycin (Van) resistance, and usage of its higher dose and short half-life are posing a serious concern. Slow and sustained release of Van using a nanodelivery system may overcome these problems. Materials & methods: Arginine-α,β-dehydrophenylalanine (RΔF) was synthesized using solution-phase synthesis which self-assembled into nanospheres. Van was entrapped in the nanoparticles (NPs). In vitro and in vivo efficacy of Van-RΔF was determined using broth microdilution and the mouse thigh infection model, respectively. Results & conclusion: Van-RΔF NPs efficiently inhibited bacterial growth (Staphylococcus aureus), while Van alone showed limited growth inhibition in in vitro. Intravenous administration of Van-RΔF in mice with bacterial thigh infection showed enhanced efficacy (double) compared with Van alone, which indicates its high potential for further development.

Phenotypic and genotypic profiling reveals a high prevalence of methicillin-resistant Staphylococcus aureus isolated from hospitals, houseflies and adjacent informal food retailers in Botswana

The increasing occurrence of methicillin-resistant Staphylococcus aureus (MRSA) in the environment, food and healthcare systems is a global public health concern. MRSA is reported to cause food poisoning, osteomyelitis and pyogenic infections of the skin, and consequently has been categorized as a high-priority pathogen by the World Health Organization. Here, we determined the presence of MRSA in clinical (n=56), food (n=150) and housefly samples (n=970) collected from two hospitals in Botswana. Characterization based on phenotypic (antimicrobial resistance, biofilm production) and genotypic (antimicrobial resistance genes and integrons) profiles were performed on all isolates. Of the total samples tested, 64 were positive for MRSA following conventional culture methods and PCR amplification of the mecA and mecC genes for confirmation of presumptive MRSA isolates. The confirmed isolates included 71 % (95 % CI 83.2-59.6) from clinical, 9 % (95 % CI 14--4.8) from food, and 1 % (95 % CI 1.6-0.4) collected from housefly samples. In total 89 % (n=57) isolates in the current study showed a multidrug resistance phenotype, among these, resistance to β-lactams and glycoside antibiotic classes were predominant. Genotypic characterization showed the domination of the blatem gene (95 %) followed by fox (63 %) and tetO (19 %) whilst vanA was only reported in 13 % of the isolates. Integrons were detected in 50 % (32/64) of the total MRSA isolates, and we report a high prevalence of etd gene, detected in 67 % (43/64) of the isolates followed by eta 38 % (24/64) whilst tsst-1 (3%) was the least detected genetic determinant. The genes etb and PVL were not detected in a ll the tested MRSA isolates. We provide the first report on the prevalence of MRSA isolated from the clinical-food-vector nexus harbouring biofilm and blatem genes, and antibiotic resistance profiles in Botswana. These results are significant for risk-assessment analysis and the development of improved MRSA infection prevention and control strategies.

Microbiology of Healthcare-Associated Infections: Results of a Fourth National Point Prevalence Survey in Serbia

Millions of patients acquire healthcare-associated infections (HAIs) every year, putting them at risk for serious complications and prolonged hospitalization. Point prevalence surveys (PPS), guided by the European Centre for Disease Prevention and Control framework, are one of the primary methods by which countries in the European Union conduct surveillance of HAIs. Serbia, though not in the EU, implemented this approach in its national PPS. The microbiological and antimicrobial resistance (AMR) analyses comprised patients in 61 out of 65 hospitals included in the fourth PPS conducted in November 2017. A total of 515/12,380 (4.2%) of the adult patients included in the PPS had at least one HAI, with intensive care units carrying the highest prevalence of 15.9%. Urinary tract and surgical site infections were the most frequently identified types of HAIs (23.9% and 23.0%, respectively). Enterobacterales comprised almost half (47.0%) of all causative agents, most notably Klebsiella spp. (16.7%). AMR was very high for most pathogens—80.5% of nonfermentative Gram-negative bacilli were resistant to carbapenems whereas 62.9% of Enterobacterales were resistant to third generation cephalosporins. The calculated AMR index of 61% is one of the highest in Europe. Further efforts are needed to reduce the burden of HAIs in Serbia that carry very high resistance rates to antibiotics currently used in clinical practice.

Antibacterial and antibiofilm activities of thiazolidine-2,4-dione and 4-thioxo-thiazolidin-2-one derivatives against multidrug-resistant Staphylococcus aureus clinical isolates

AIMS

Antimicrobial resistance is one of the highest priorities in global public health with Staphylococcus aureus among the most important microorganisms due to its rapidly evolving antimicrobial resistance. Despite all the efforts of antimicrobial stewardship, research and development of new antimicrobials are still imperative. The thiazolidine ring is considered a privileged structure for the development of new antimicrobials. This study aimed to compare the antibacterial effects of two analog series of thiazolidine-2,4-dione and 4-thioxo-thiazolidin-2-one against multidrug-resistant Staphylococcus aureus clinical isolates.

METHODS AND RESULTS

The derivatives 1a, 2a, and 2b exhibited MIC between 1-32 μg.mL^-1 , with time-to-kill curves showing a bactericidal effect up to 24 h. In the antibiofilm assay, the most active derivatives were able to inhibit about 90% of biofilm formation. The 4-thioxo-thiazolidine-2-one derivatives were more active against planktonic cells, while the thiazolidine-2,4-dione derivatives were able to disrupt about 50% of the preformed biofilm. In the in vivo infection model using Caenorhabditis elegans as a host, the derivatives 1a, 2a, and 2b increased nematode survival with a concentration-dependent effect. Exposure of S. aureus to the derivatives 2a and 2b induced surface changes and decrease cell size. None of the derivatives was cytotoxic for human peripheral blood mononuclear cells (PBMC) but showed moderate cytotoxicity for L929 fibroblasts.

CONCLUSION

The 5-(3,4-dichlorobenzylidene)-4-thioxothiazolidin-2-one (2b) was the most active derivative against S. aureus and showed the higher selective indexes.

SIGNIFICANCE AND IMPACT OF STUDY

4-thioxo-thiazolidin-2-one are a promising scaffold for the research and development of new antimicrobial drugs against multidrug-resistant S. aureus.

Antibacterial activity of recently approved antibiotics against methicillin-resistant Staphylococcus aureus (MRSA) strains: A systematic review and meta-analysis

Background

Methicillin-resistant Staphylococcus aureus (MRSA) infections are considered an important public health problem, and treatment options are limited. Accordingly, in this meta-analysis, we analyzed published studies to survey in vitro activity of recently approved antibiotics against MRSA isolates.

Methods

We searched electronic databases; PubMed, Scopus, and Web of Science to identify relevant studies (until November 30, 2020) that have focused on the in vitro activity of telavancin, dalbavancin, oritavancin, and tedizolid against MRSA isolates. Statistical analyses were conducted using STATA software (version 14.0).

Results

Thirty-eight studies were included in this meta-analysis. Overall in vitro activity of tedizolid on 12,204 MRSA isolates was 0.250 and 0.5 µg/mL for MIC₅₀ and MIC₉₀, (minimum inhibitory concentration at which 50% and 90% of isolates were inhibited, respectively), respectively. The overall antibacterial activity of dalbavancin on 28539 MRSA isolates was 0.060 and 0.120 µg/mL for MIC₅₀ and MIC₉₀, respectively. The overall antibacterial activity of oritavancin on 420 MRSA isolates was 0.045 and 0.120 µg/mL for MIC₅₀ and MIC₉₀, respectively. The overall antibacterial activity of telavancin on 7353 MRSA isolates was 0.032 and 0.060 µg/mL for MIC₅₀ and MIC₉₀, respectively. The pooled prevalence of tedizolid, telavancin, and dalbavancin susceptibility was 100% (95% CI: 100–100).

Conclusion

Telavancin, dalbavancin, oritavancin, and tedizolid had potent in vitro activity against MRSA isolates. The low MICs and high susceptibility rates of these antibiotics recommend a hopeful direction to introduce useful antibiotics in treating MRSA infections in the future.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12941-022-00529-z.

Antibiotic resistance: The challenges and some emerging strategies for tackling a global menace

Background

Antibiotic resistance is currently the most serious global threat to the effective treatment of bacterial infections. Antibiotic resistance has been established to adversely affect both clinical and therapeutic outcomes, with consequences ranging from treatment failures and the need for expensive and safer alternative drugs to the cost of higher rates of morbidity and mortality, longer hospitalization, and high‐healthcare costs. The search for new antibiotics and other antimicrobials continues to be a pressing need in humanity's battle against bacterial infections. Antibiotic resistance appears inevitable, and there is a continuous lack of interest in investing in new antibiotic research by pharmaceutical industries. This review summarized some new strategies for tackling antibiotic resistance in bacteria.

Methods

To provide an overview of the recent research, we look at some new strategies for preventing resistance and/or reviving bacteria's susceptibility to already existing antibiotics.

Results

Substantial pieces of evidence suggest that antimicrobials interact with host immunity, leading to potent indirect effects that improve antibacterial activities and may result in more swift and complete bactericidal effects. A new class of antibiotics referred to as immuno‐antibiotics and the targeting of some biochemical resistance pathway components including inhibition of SOS response and hydrogen sulfide as biochemical underlying networks of bacteria can be considered as new emerging strategies to combat antibiotic resistance in bacteria.

Conclusion

This review highlighted and discussed immuno‐antibiotics and inhibition of SOS response and hydrogen sulfide as biochemical underlying networks of bacteria as new weapons against antibiotic resistance in bacteria.

Modern vaccine development via reverse vaccinology to combat antimicrobial resistance

With the continuous evolution of bacteria, the global antimicrobial resistance health threat is causing millions of deaths yearly. While depending on antibiotics as a primary treatment has its merits, there are no effective alternatives thus far in the pharmaceutical market against some drug-resistant bacteria. In recent years, vaccinology has become a key topic in scientific research. Combining with the growth of technology, vaccine research is seeing a new light where the process is made faster and more efficient. Although less discussed, bacterial vaccine is a feasible strategy to combat antimicrobial resistance. Some vaccines have shown promising results with good efficacy against numerous multidrug-resistant strains of bacteria. In this review, we aim to discuss the findings from studies utilizing reverse vaccinology for vaccine development against some multidrug-resistant bacteria, as well as provide a summary of multi-year bacterial vaccine studies in clinical trials. The advantages of reverse vaccinology in the generation of new bacterial vaccines are also highlighted. Meanwhile, the limitations and future prospects of bacterial vaccine concludes this review.

Engineered device in E. coli lyses S. aureus at physiological fever temperatures

Multiple strains of Staphylococcus are resistant to antibiotics, including the well-known methicillin-resistant Staphylococcus aureus (MRSA). We share an engineered plasmid device in Escherichia coli that lyses the disease-causing pathogen, S. aureus. The device was engineered using BioBrick parts obtained from the International Genetically Engineered Machine foundation (iGEM). The cI-blue-lysostaphin device consists of a temperature-sensitive promoter that is activated under physiological fever temperatures above 35°C that drives expression of a blue chromoprotein reporter and mature truncated lysostaphin enzyme. The functioning cI-blue-lysostaphin device was tested for optimal lysis conditions in MM294 and DH5α E. coli chassis and across incubation temperatures ranging from 30-42°C. We conclude that the lysostaphin activity of the cI-blue-lysostaphin device differs between chassis and increases with greater incubation temperature.

Prevalence of ESKAPE pathogens in the environment: Antibiotic resistance status, community-acquired infection and risk to human health

The ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) pathogens are characterised by increased levels of resistance towards multiple classes of first line and last-resort antibiotics. Although these pathogens are frequently isolated from clinical environments and are implicated in a variety of life-threatening, hospital-associated infections; antibiotic resistant ESKAPE strains have been isolated from environmental reservoirs such as surface water, wastewater, food, and soil. Literature on the persistence and subsequent health risks posed by the ESKAPE isolates in extra-hospital settings is however, limited and the current review aims to elucidate the primary reservoirs of these pathogens in the environment, their antibiotic resistance profiles, and the link to community-acquired infections. Additionally, information on the current state of research regarding health-risk assessments linked to exposure of the ESKAPE pathogens in the natural environment, is outlined.

Enterotoxin- and Antibiotic-Resistance-Encoding Genes Are Present in Both Coagulase-Positive and Coagulase-Negative Foodborne Staphylococcus Strains

Food poisoning by staphylococcal enterotoxins (SE) is a major cause of foodborne illness, often associated with coagulase-positive staphylococci (CPS). The increase in the number of methicillin-resistant Staphylococcus aureus (MRSA) strains is another major problem associated with CPS. However, reports of the association of SE and methicillin-resistant Staphylococcus with coagulase-negative staphylococci (CNS) are beginning to re-emerge. In this context, the aim of this study is to investigate the presence of staphylococcal enterotoxin genes and to characterize the phenotypic and genotypic antimicrobial resistance in 66 isolates of Staphylococcus spp. (47 CNS and 19 CPS) recovered from ready-to-eat (RTE) street food sold in Maputo, Mozambique. Seven virulence genes encoding SE (sea, seb, sec, sed and see) and two toxins (hlb and sak) were screened by multiplex PCR (MPCR). Antimicrobial resistance against 12 antibiotics was evaluated by the disk diffusion method. The presence of genes encoding resistance to penicillin, methicillin, vancomycin and erythromycin (blaZ, mecA, vancA, vancB, ermA, ermB and ermC) were also screened by PCR. At least one of the seven virulence genes assessed in this study was detected in 57.9% and 51% of CPS and CNS isolates, respectively. In CPS isolates, the most frequent gene was hlb (47.4%), followed by sec (15.8%) and sea, seb and sed genes with 5.3% each. In CNS isolates, the most frequent gene was sec (36.2%) followed by sak (17%), hlb (14.9%), sed (12.8%) and seb (6.4%). Five of the twelve CPS in which virulence genes were detected were also antibiotic-resistant. All the CNS isolates harboring virulence genes (n = 27, 57.4%) were antimicrobial-resistant. The prevalence of multidrug resistance was higher (59.6%) in CNS than in CPS (26.3%) isolates. Regarding the presence of antibiotic-resistance genes, blaZ (penicillin-resistant) was the most frequent in both CPS (42.1%) and CNS (87.2%), followed by the mecA (encoding methicillin resistance) and vancA genes (vancomycin-resistant), which represented 36.8% and 31.6% in CPS isolates and 46.8% in CNS isolates, respectively. The prevalence of vancomycin-resistant staphylococci has been increasing worldwide and, to our knowledge, this is the first study to report the occurrence of vancomycin-resistant staphylococci in Mozambique. These results emphasize the need to investigate CNS isolates in parallel with CPS, as both constitute public health hazards, given their potential to produce SE and spread antimicrobial resistance genes.

High prevalence and expression of antiseptic resistance genes among infectious t037/ST239 methicillin-resistant Staphylococcus aureus (MRSA) strains in North Khorasan Province, Iran

OBJECTIVES

Staphylococcus aureus is an important infectious agent and the majority of methicillin-resistant S. aureus (MRSA) infections are of nosocomial origin. To define the level and distribution of antiseptic resistance among infectious S. aureus strains we studied MRSA and methicillin-susceptible S. aureus (MSSA) isolates collected from different infection sites in an assortment of patients.

MATERIALS AND METHODS

S. aureus isolates were investigated for in vitro susceptibility to antiseptic agents and detection of qacA/B, smr, vanA, and mecA genes.

RESULTS

Among the S. aureus isolates we studied, 25 and 41 were MRSA and MSSA, respectively. The mean of minimum inhibitory concentrations (MICs) for benzethonium chloride (BTC) among MRSA was statistically significantly higher than for MSSA (26 µg/ml versus 11.7 µg/ml, P=0.003) while there was no significant difference between MRSA and MSSA for benzalkonium chloride (BKC) and chlorhexidine digluconate (CHG). The qacA/B genes were carried in 68% of the MRSA and 58.2% of MSSA (P=0.601), while smr was carried in 39% of MRSA and 29.3% of MSSA strains (P=1.000). In 15 out of 25 cases, MRSA ST239 with spa types t037, t030, and t7688 was isolated from the infection site with 86.6% of them carrying a resistance gene (qacA/B or qacA/B + smr).

CONCLUSION

The frequent presence of antiseptic resistance genes and a consequently elevated MIC against antiseptics among ST239 MRSA emphasizes the importance of mandatorily monitoring MRSA for effective infection control.

Effect of spdC gene expression on virulence and antibiotic resistance in clinical Staphylococcus aureus isolates

Surface protein display C (SpdC) protein was described as a novel virulence factor of Staphylococcus aureus that affects biofilm formation and pathogenesis and favors resistance to antimicrobials targeting cell wall. We evaluated the possible correlation between spdC gene expression level and virulence as well as antibiotic resistance phenotypes in S. aureus clinical isolates. The antimicrobial susceptibility of S. aureus clinical isolates (n = 100) was determined by the disk diffusion method. Vancomycin susceptibility was determined by the broth microdilution method. The level of the extracellular proteases and delta-hemolysin was evaluated by measuring the proteolysis and hemolysis zone diameters in skim milk and blood agar plates, respectively. Biofilm formation was assayed using the 96-well microtiter plate method. Most of the isolates (81%) were multidrug-resistant and about half of the isolates (49%) were methicillin-resistant S. aureus. Hemolysin, protease, and biofilm production were detectable in 79%, 71%, and 96% of the isolates. No significant correlation was detectable between the level of spdC gene expression and the activity of tested virulence factors or the antimicrobial resistance phenotype. Therefore, the role of SpdC protein as a virulence regulator in S. aureus needs further evaluation together with the determination of the predominant regulators for each virulence factor.

Microbial Resistance to Antibiotics and Effective Antibiotherapy

Currently, the efficacy of antibiotics is severely affected by the emergence of the antimicrobial resistance phenomenon, leading to increased morbidity and mortality worldwide. Multidrug-resistant pathogens are found not only in hospital settings, but also in the community, and are considered one of the biggest public health concerns. The main mechanisms by which bacteria develop resistance to antibiotics include changes in the drug target, prevention of entering the cell, elimination through efflux pumps or inactivation of drugs. A better understanding and prediction of resistance patterns of a pathogen will lead to a better selection of active antibiotics for the treatment of multidrug-resistant infections.

Synthesis, Stereochemical Confirmation, and Derivatization of 12( S ),16ϵ‐Dihydroxycleroda‐3,13‐dien‐15,16‐olide, a Clerodane Diterpene That Sensitizes Methicillin‐Resistant Staphylococcus aureus to β‐Lactam Antibiotics

Over the past decades, antibiotic resistance has grown to a point where orthogonal approaches to combating infections caused by resistant bacteria are needed. One such approach is the development of non-microbicidal small molecules that potentiate the activity of conventional antibiotics, termed adjuvants. The diterpene natural product 12(S),16ϵ-dihydroxycleroda-3,13-dien-15,16-olide, which we refer to as (-)-LZ-2112, is known to synergize with oxacillin against methicillin-resistant Staphylococcus aureus (MRSA). To explore this activity, (-)-LZ-2112 was synthesized and the structure confirmed through X-ray analysis. Preliminary structure-activity relationship studies following the synthesis of several analogs identified key structural elements responsible for activity and indicate that scaffold simplification is possible. A preliminary mode of action study suggests mecA plays a role in the adjuvant activity of (-)-LZ-2112.

Application of Nanomaterials in the Prevention, Detection, and Treatment of Methicillin-Resistant Staphylococcus aureus (MRSA)

Due to differences in geographic surveillance systems, chemical sanitization practices, and antibiotic stewardship (AS) implementation employed during the COVID-19 pandemic, many experts have expressed concerns regarding a future surge in global antimicrobial resistance (AMR). A potential beneficiary of these differences is the Gram-positive bacteria MRSA. MRSA is a bacterial pathogen with a high potential for mutational resistance, allowing it to engage various AMR mechanisms circumventing conventional antibiotic therapies and the host’s immune response. Coupled with a lack of novel FDA-approved antibiotics reaching the clinic, the onus is on researchers to develop alternative treatment tools to mitigate against an increase in pathogenic resistance. Mitigation strategies can take the form of synthetic or biomimetic nanomaterials/vesicles employed in vaccines, rapid diagnostics, antibiotic delivery, and nanotherapeutics. This review seeks to discuss the current potential of the aforementioned nanomaterials in detecting and treating MRSA.

Recent Developments in Phenotypic and Molecular Diagnostic Methods for Antimicrobial Resistance Detection in Staphylococcus aureus: A Narrative Review

Staphylococcus aureus is an opportunistic pathogen responsible for a wide range of infections in humans, such as skin and soft tissue infections, pneumonia, food poisoning or sepsis. Historically, S. aureus was able to rapidly adapt to anti-staphylococcal antibiotics and become resistant to several classes of antibiotics. Today, methicillin-resistant S. aureus (MRSA) is a multidrug-resistant pathogen and is one of the most common bacteria responsible for hospital-acquired infections and outbreaks, in community settings as well. The rapid and accurate diagnosis of antimicrobial resistance in S. aureus is crucial to the early initiation of directed antibiotic therapy and to improve clinical outcomes for patients. In this narrative review, I provide an overview of recent phenotypic and molecular diagnostic methods for antimicrobial resistance detection in S. aureus, with a particular focus on MRSA detection. I consider methods for resistance detection in both clinical samples and isolated S. aureus cultures, along with a brief discussion of the advantages and the challenges of implementing such methods in routine diagnostics.

In Vitro Activity of Vancomycin, Teicoplanin, Linezolid and Daptomycin Against Methicillin-Resistant Staphylococcus aureus Isolates Collected from Chinese Hospitals in 2018-2020

Introduction

Vancomycin, teicoplanin, linezolid and daptomycin are four major antibacterials used for methicillin-resistant Staphylococcus aureus (MRSA) infection treatment. However, with the increasing failure of clinical MRSA anti-infective treatment, it is urgent to investigate the status of MRSA sensitivity to these four drugs.

Methods

In the present study, 407 non-duplicated MRSA isolates from 6 provinces in China were collected from January 2018 to August 2020. The minimum inhibitory concentrations (MICs) of vancomycin, teicoplanin, linezolid and daptomycin were determined by broth microdilution method, and their MIC50, MIC90, and geometric mean MIC were calculated.

Results

All 407 MRSA strains were sensitive to these four antibacterials. MIC range of vancomycin, teicoplanin, linezolid and daptomycin was 0.25 to 2 mg/L, 0.125 to 4 mg/L, 0.25 to 4 mg/L and 0.06 to 1 mg/L, respectively. Between 2018 and 2020, there was no “MIC creep” in vancomycin, teicoplanin and daptomycin. The geometric mean MIC of linezolid was not increased, but both MIC50 and MIC90 in 2019 and 2020 MRSA isolates were higher than 2018 isolates.

Conclusion

All MRSA isolates remained sensitivity to vancomycin, teicoplanin, linezolid and daptomycin. The linezolid MIC50 and MIC90 increased have been found in this study.

Mechanisms of gram-positive vancomycin resistance (Review)

Vancomycin-resistant bacteria (VRB) are important consideration in medicine and public health as they can cause life-threatening infections that appear to be resistant to therapy and persist in the body after medication. A wide spectrum of antimicrobial resistance characteristics, as well as various environmental and animal settings underlie the evolution of the most prevalent the most prevalent van genes in the VRB genome, indicating significant gene flow. As illnesses caused by VRB have become increasingly complex, several previously effective therapeutic techniques have become ineffective, complicating clinical care further. The focus of this review is the mechanism of vancomycin resistance in Enterococci, Staphylococci and Lactobacilli.

Educational Activities for Students and Citizens Supporting the One-Health Approach on Antimicrobial Resistance

Antibiotic resistance is one of the biggest threats to global health, food security and development. Urgent action is needed at all levels of society to reduce the impact and spread of antibiotic resistance. For a more sustaining approach, education in children, college students, citizens and caregivers are essential. The One-Heath approach is a collaborative, multisectoral and transdisciplinary strategy in which, no single organizations or sector can address the issue of antimicrobial resistance at the human-environment interface alone. Within this strategy, education plays a central role. In this scoping review, we highlighted a range of learning activities on antibiotic resistance as part of the One-Health approach. In particular, those applications that can be introduced to a wide audience to help arrest the current crisis for the next generation. The review identifies a high number of teaching opportunities: board and role-play games, round tables, musicals, e-learning and environmental experiments to couple with more curricula and formal education to inform a diverse group of audiences.

Isolation and Genetic Characterization of Vancomycin-resistant and mecC+ Methicillin-resistant Staphylococcus aureus Strains in Clinical Samples of Bojnurd, Northeastern Iran

Background: The emergence of antibiotic-resistant Staphylococcus aureus strains is one of the major concerns about the various staphylococcal infections. Vancomycin is one the most important effective antibiotics on staphylococcal lethal infections. To date, vancomycin-resistant strains are increasingly isolated in different parts of the world, and it is alerting. Objectives: The current study was designed to evaluate the prevalence, and antibiotic susceptibility pattern of methicillin-resistant S. aureus (MRSA) and vancomycin-resistant S. aureus (VRSA) isolates in the main tertiary hospital of Bojnurd, Iran. Methods: Staphylococcus aureus isolates were collected from different clinical samples in Imam Reza Hospital of Bojnurd. After identification of isolates through using conventional methods, they were evaluated by agar screening, disk diffusion, and minimum inhibitory concentration (MIC) methods to determine resistance to vancomycin and methicillin. We also performed polymerase chain reaction (PCR) for the detection of mecA, mecC, vanA, and vanB genes. After confirmation of vancomycin resistance, genetic analysis was performed using SCCmec, agr, and spa typing, and multilocus sequence typing (MLST) methods on VRSA isolates. Results: We found four vancomycin-resistant isolates (1.29%). Also, 75% of isolates were resistant to cefoxitin. Using the PCR method, mecA was found in 73%, mecC in 0.64%, and vanA in 1.29% of isolates. Interestingly, we found two mecC positive isolates in MRSA isolates. The alpha-hemolysin (81.81%) and enterotoxin C (27%) had the highest and lowest toxins percentage, respectively. Among mecA positive isolates, SCCmec IV (37%), SCCmec III (31.27%), SCCmec I (14%), SCCmec II (11%), and SCCmec V (5.7%) were the most prevalent SCCmec types, respectively. It should be noted that the two mecC positive isolates belonged to SCCmec XI. Agr I (76.29%) was the highest agr type. We recognized t037 as the dominant spa type, and ST239, ST6, ST97, and ST8 were found in VRSA isolates. Conclusions: In our study, the frequency of mecA genes in MRSA isolates was very high. It seems that the resistant isolates belonged to endemic clones of Iran.

The Impact of COVID-19 on the Profile of Hospital-Acquired Infections in Adult Intensive Care Units

Hospital-acquired infections (HAIs) are a global public health concern. As the COVID-19 pandemic continues, its contribution to mortality and antimicrobial resistance (AMR) grows, particularly in intensive care units (ICUs). A two-year retrospective study from April 2019-April 2021 was conducted in an adult ICU at the Hospital for Infectious and Tropical Diseases, Belgrade, Serbia to assess causative agents of HAIs and AMR rates, with the COVID-19 pandemic ensuing halfway through the study. Resistance rates >80% were observed for the majority of tested antimicrobials. In COVID-19 patients, Acinetobacter spp. was the dominant cause of HAIs and more frequently isolated than in non-COVID-19 patients. (67 vs. 18, p = 0.001). Also, resistance was higher for imipenem (56.8% vs. 24.5%, p < 0.001), meropenem (61.1% vs. 24.3%, p < 0.001) and ciprofloxacin (59.5% vs. 36.9%, p = 0.04). AMR rates were aggregated with findings from our previous study to identify resistance trends and establish empiric treatment recommendations. The increased presence of Acinetobacter spp. and a positive trend in Klebsiella spp. resistance to fluoroquinolones (R² = 0.980, p = 0.01) and carbapenems (R² = 0.963, p = 0.02) could have contributed to alarming resistance rates across bloodstream infections (BSIs), pneumonia (PN), and urinary tract infections (UTIs). Exceptions were vancomycin (16.0%) and linezolid (2.6%) in BSIs; tigecycline (14.3%) and colistin (0%) in PNs; and colistin (12.0%) and linezolid (0%) in UTIs. COVID-19 has changed the landscape of HAIs in our ICUs. Approval of new drugs and rigorous surveillance is urgently needed.