Antimicrobial Resistance Genes Research Articles

Clinical Utility of Blood Culture Identification 2 Panel in Flagged Blood Culture Samples from the Intensive Care Unit of a Tertiary Care Hospital.

The availability of rapid diagnostic platforms for positive blood cultures has accelerated the speed at which the clinical microbiology laboratory can identify the causative organism and facilitate early appropriate antimicrobial therapy. There is a paucity of data regarding the clinical utility of the blood culture identification 2 (BCID2) panel test and its correlation with phenotypic drug susceptibility testing (DST) in flagged blood culture bottles from intensive care units (ICUs) in countries such as India, which have high rates of multidrug-resistant gram-negative bacteria (MDR-GNB). We conducted a retrospective observational study in a tertiary care ICU on 200 patients above 18 years of age in whom a BCID2 test was ordered when blood cultures flagged positive. We found 99% concordance between BCID2 and cultures in the identification of bacteria and yeasts and 96.5% concordance between phenotypic and genotypic DST. Furthermore, BCID2 was available about 1.5 days earlier than conventional ID and DST and played a key role in tailoring antimicrobials in 82.5% of the patients. Polymyxin-based therapy was discontinued earlier after an empiric dose in 138 patients (69%) based on BCID2 reports. In critically ill patients with monomicrobial bacteremia, BCID2 rapidly identifies bacteria and antimicrobial resistance (AMR) genes and is significantly faster than conventional culture and sensitivity testing. Antibiotics were escalated in more than a third of patients and de-escalated in almost a fifth on the same day. We recommend that all ICUs routinely incorporate the test in their antibiotic decision-making process and in antimicrobial stewardship. Vineeth VK, Nambi PS, Gopalakrishnan R, Sethuraman N, Ramanathan Y, Chandran C, et al. Clinical Utility of Blood Culture Identification 2 Panel in Flagged Blood Culture Samples from the Intensive Care Unit of a Tertiary Care Hospital. Indian J Crit Care Med 2024;28(5):461-466.

Genome analyses of colistin-resistant high-risk blaNDM-5 producing Klebsiella pneumoniae ST147 and Pseudomonas aeruginosa ST235 and ST357 in clinical settings

BackgroundColistin is a last-resort antibiotic used in extreme cases of multi-drug resistant (MDR) Gram-negative bacterial infections. Colistin resistance has increased in recent years and often goes undetected due to the inefficiency of predominantly used standard antibiotic susceptibility tests (AST). To address this challenge, we aimed to detect the prevalence of colistin resistance strains through both Vitek®2 and broth micro-dilution. We investigated 1748 blood, tracheal aspirate, and pleural fluid samples from the Intensive Care Unit (ICU), Neonatal Intensive Care Unit (NICU), and Tuberculosis and Respiratory Disease centre (TBRD) in an India hospital. Whole-genome sequencing (WGS) of extremely drug-resitant (XDR) and pan-drug resistant (PDR) strains revealed the resistance mechanisms through the Resistance Gene Identifier (RGI.v6.0.0) and Snippy.v4.6.0. Abricate.v1.0.1, PlasmidFinder.v2.1, MobileElementFinder.v1.0.3 etc. detected virulence factors, and mobile genetic elements associated to uncover the pathogenecity and the role of horizontal gene transfer (HGT).ResultsThis study reveals compelling insights into colistin resistance among global high-risk clinical isolates: Klebsiella pneumoniae ST147 (16/20), Pseudomonas aeruginosa ST235 (3/20), and ST357 (1/20). Vitek®2 found 6 colistin-resistant strains (minimum inhibitory concentrations, MIC = 4 μg/mL), while broth microdilution identified 48 (MIC = 32–128 μg/mL), adhering to CLSI guidelines. Despite the absence of mobile colistin resistance (mcr) genes, mechanisms underlying colistin resistance included mgrB deletion, phosphoethanolamine transferases arnT, eptB, ompA, and mutations in pmrB (T246A, R256G) and eptA (V50L, A135P, I138V, C27F) in K. pneumoniae. P. aeruginosa harbored phosphoethanolamine transferases basS/pmrb, basR, arnA, cprR, cprS, alongside pmrB (G362S), and parS (H398R) mutations. Both strains carried diverse clinically relevant antimicrobial resistance genes (ARGs), including plasmid-mediated blaNDM-5 (K. pneumoniae ST147) and chromosomally mediated blaNDM-1 (P. aeruginosa ST357).ConclusionThe global surge in MDR, XDR and PDR bacteria necessitates last-resort antibiotics such as colistin. However, escalating resistance, particularly to colistin, presents a critical challenge. Inefficient colistin resistance detection methods, including Vitek2, alongside limited surveillance resources, accentuate the need for improved strategies. Whole-genome sequencing revealed alarming colistin resistance among K. pneumoniae and P. aeruginosa in an Indian hospital. The identification of XDR and PDR strains underscores urgency for enhanced surveillance and infection control. SNP analysis elucidated resistance mechanisms, highlighting the complexity of combatting resistance.

Complete genome sequence of the linezolid-resistant clinical Enterococcus faecalis N23-3408 linked to a livestock lineage in Switzerland.

Here, we report the complete genome of human clinical linezolid-resistant Enterococcus faecalis N23-3408. N23-3408 harbored a 59.5 kb plasmid with antimicrobial resistance genes cat, erm(B), fexA, optrA, tet(L), and tet(M). Closely related E. faecalis harboring this plasmid was previously obtained from livestock animals and pet food in Switzerland.

Comparative microbiome analysis in cystic fibrosis and non-cystic fibrosis bronchiectasis.

Bronchiectasis is a condition characterized by abnormal and irreversible bronchial dilation resulting from lung tissue damage and can be categorized into two main groups: cystic fibrosis (CF) and non-CF bronchiectasis (NCFB). Both diseases are marked by recurrent infections, inflammatory exacerbations, and lung damage. Given that infections are the primary drivers of disease progression, characterization of the respiratory microbiome can shed light on compositional alterations and susceptibility to antimicrobial drugs in these cases compared to healthy individuals. To assess the microbiota in the two studied diseases, 35 subjects were recruited, comprising 10 NCFB and 13 CF patients and 12 healthy individuals. Nasopharyngeal swabs and induced sputum were collected, and total DNA was extracted. The DNA was then sequenced by the shotgun method and evaluated using the SqueezeMeta pipeline and R. We observed reduced species diversity in both disease cohorts, along with distinct microbial compositions and profiles of antimicrobial resistance genes, compared to healthy individuals. The nasopharynx exhibited a consistent microbiota composition across all cohorts. Enrichment of members of theBurkholderiaceaefamily and an increased Firmicutes/Bacteroidetes ratio in the CF cohort emerged as key distinguishing factors compared to NCFB group.Staphylococcus aureusand Prevotella shahii also presented differential abundance in the CF and NCFB cohorts, respectively, in the lower respiratory tract. Considering antimicrobial resistance, a high number of genes related to antibiotic efflux were detected in both disease groups, which correlated with the patient's clinical data. Bronchiectasis is associated with reduced microbial diversity and a shift in microbial and resistome composition compared to healthy subjects. Despite some similarities, CF and NCFB present significant differences in microbiome composition and antimicrobial resistance profiles, suggesting the need for customized management strategies for each disease.

Genomic insights unveil the plasmid transfer mechanism and epidemiology of hypervirulent Klebsiella pneumoniae in Vietnam.

Hypervirulent Klebsiella pneumoniae (hvKp) is a significant cause of severe invasive infections in Vietnam, yet data on its epidemiology, population structure and dynamics are scarce. We screened hvKp isolates from patients with bloodstream infections (BSIs) at a tertiary infectious diseases hospital in Vietnam and healthy individuals, followed by whole genome sequencing and plasmid analysis. Among 700 BSI-causing Kp strains, 100 (14.3%) were hvKp. Thirteen hvKp isolates were identified from 350 rectal swabs of healthy adults; none from 500 rectal swabs of healthy children. The hvKp isolates were genetically diverse, encompassing 17 sequence types (STs), predominantly ST23, ST86 and ST65. Among the 113 hvKp isolates, 14 (12.6%) carried at least one antimicrobial resistance (AMR) gene, largely mediated by IncFII, IncR, and IncA/C plasmids. Notably, the acquisition of AMR conjugative plasmids facilitated horizontal transfer of the non-conjugative virulence plasmid between K. pneumoniae strains. Phylogenetic analysis demonstrated hvKp isolates from BSIs and human carriage clustered together, suggesting a significant role of intestinal carriage in hvKp transmission. Enhanced surveillance is crucial to understand the factors driving intestinal carriage and hvKp transmission dynamics for informing preventive measures. Furthermore, we advocate the clinical use of our molecular assay for diagnosing hvKp infections to guide effective management.

Antimicrobial Resistance and ARGs Detection in Treated Final Effluent from STPs: An Upcoming Challenge to the Environment

Aim: The present study analysed the presence of antimicrobial resistance organisms and genes in the final effluent from STPs of hospitals. Study Area and Sampling: Samples for microbiological analysis were collected from two different hospitals in Trivandrum City and carried out further microbiological analysis. Methodology: In this study, MDRB (Multi Drug Resiatant Bacteria) were detected from the hospital effluent samples collected from two hospitals. Antibiotic susceptibility analysis showed that the 90% screened organisms was resistant to different antibiotics -Tetracycline (30µg), Amikacin (30µg), Gentamycin (10µg), Ciprofloxacin (5µg), Colistin (10µg) and Amoxicillin (30µg)). Metagenomic surveillance of effluent helped to assess the efficacy of STPs, at the same time assessing the local clinical antibiotic resistance condition by detection of the presence of antimicrobial resistance towards antibiotics and their genes (ARGs) in the hospital effluent. Results: In this study, a total of 3 antibiotic resistant bacterial strains obtained from hospital STP effluent were identified by16S rRNA sequence analysis. The sequences of E.coli, Klebsiella and Enterobacter were submitted in Genbank with accession number MT784125, OM978270 andMN437586 respectively.The final effluent from Hospital 1 showed100% resistance to Tetracycline and 86% resistance to Amoxicillin followed by sensitivity 28%, 22%, 18% and 10% respectively to Ciprofloxacin, Gentamycin, Amikacin and Colistin. The bacterial strains isolated from final effluent of Hospital 2 showed highest resistance to Amikacin and Colistin which is 100% and 86% and 82% resistance to Gentamycin and Ciprofloxacin. The gene primers used for the respective genes above have been amplified in the sample with a higher efficiency of 16 SrRNA, ermB and ampC primers showing a lower Cq value. Thus, these three genes were detected in the samples at high amount which showed the prominent use of the consecutive antibiotics in the clinical field

Investigation of the epidemiology, pathogenicity and immunogenicity of Bordetella bronchiseptica isolated from cats and dogs in China from 2021 to 2023

Bordetella bronchiseptica (Bb) is recognized as a leading cause of respiratory diseases in dogs and cats. However, epidemiological data on Bb in dogs and cats in China are still limited, and there is no commercially available vaccine. Live vaccines containing Bb that are widely used abroad are generally effective but can establish latency and potentially reactivate to cause illness in some immunodeficient vaccinated recipients, raising safety concerns. In this study, 34 canine-derived and two feline-derived Bb strains were isolated from 1809 canine and 113 feline nasopharyngeal swab samples collected from eight provinces in China from 2021 to 2023. The PCR results showed that the percentage of positive Bb was 22.94% (441/1922), and more than 90% of the Bb isolates had four virulence factor-encoding genes (VFGs), namely, fhaB, prn, betA and dnt. All the isolated strains displayed a multidrug-resistant phenotype. The virulence of 10 Bb strains isolated from dogs with respiratory symptoms was tested in mice, and we found that eight isolates were highly virulent. Furthermore, the eight Bb isolates with high virulence were inactivated and intramuscularly injected into mice, and three Bb strains (WH1218, WH1203 and WH1224) with the best protective efficacy were selected. Dogs immunized with these three strains exhibited strong protection against challenge with the Bb field strain WH1218. Ultimately, the WH1218 strain with the greatest protection in dogs was selected as the vaccine candidate. Dogs and cats that received a vaccine containing 109 CFU of the inactivated WH1218 strain showed complete protection against challenge with the Bb field strain WH1218. This study revealed that Bb is an important pathogen that causes respiratory diseases in domestic dogs and cats in China, and all the isolates exhibited multidrug resistance. The present work contributes to the current understanding of the prevalence, antimicrobial resistance, and virulence genes of Bb in domestic dogs and cats. Additionally, our results suggest that the WH1218 strain is a promising candidate safe and efficacious inactivated Bb vaccine.

Antimicrobial resistance determinants in the oropharyngeal microbiome of 'men having sex with men' attending an sexually transmitted infection clinic.

'Men having sex with men' (MSM) represent a key population with a significant prevalence of pharyngeal Neisseria gonorrhoeae (NG) infections and a high rate of antimicrobial resistance genes in the pharyngeal microbiome. As NG can acquire antibiotic resistance genes from other commensal oropharyngeal bacteria, monitoring the prevalence of these resistance determinants is critical to curtail the spread of NG-resistant strains. Here, we assessed the distribution of five resistance genes (pen (A), mtr (R), gyr (A), par (C), msr (D)) in the oropharynx of 164 MSM, attending an Outpatient clinic for STI screening. The most frequently detected resistance gene was msr (D) (88.4%), followed by gyr (A) (67.1%). The distribution of resistance genes was not influenced by pharyngeal gonorrhea nor by the HIV status, whereas a younger age was associated with mtr (R) presence (p = .008). Subjects using mouthwash exhibited significantly lower levels of mtr (R) (p = .0005). Smoking habit was associated with a higher prevalence of par (C) (p = .02). A noteworthy association was observed between the presence of msr (D) gene and the use of antibiotics (p = .014). Our findings reveal an enrichment of antimicrobial resistance genes in the oropharynx of MSM. These insights could aid in the development of screening programs and antimicrobial stewardship initiatives targeting populations at heightened risk of pharyngeal gonorrhea.

Clinical presentation, antimicrobial resistance, and treatment outcomes of Aeromonas human infections: A 14-year retrospective study and comparative genomics of two isolates from fatal cases.

Aeromonas virulence may not be entirely dependent on the host immune status. Pathophysiologic determinants of disease progression and severity remain unclear. One hundred five patients with Aeromonas infections and 112 isolates were identified, their clinical presentations and outcomes analyzed, and their antimicrobial resistance (AMR) patterns assessed. Two isolates (A and B) from fatal cases of Aeromonas dhakensis bacteremia were characterized using whole genome sequence analysis. Virulence factor- and AMR-encoding genes from these isolates were compared with a well-characterized diarrheal isolate A. dhakensis SSU, and environmental isolate A. hydrophila ATCC_7966T. Skin and soft tissue infections, traumatic wound infections, sepsis, burns, and intraabdominal infections were common. Diabetes, malignancy, and cirrhosis were frequent comorbidities. Male sex, age ≥ 65 years, hospitalization, burns, and intensive care were associated with complicated disease. High rates of AMR to carbapenems and piperacillin-tazobactam were found. Treatment failure was observed in 25.7% of cases. Septic shock and hospital-acquired infections were predictors of treatment failure. All four isolates harbored assorted broad-spectrum AMR genes including blaOXA, ampC, cphA, and efflux pumps. Only clinical isolates possessed both polar and lateral flagellar genes, genes for various surface adhesion proteins, type 3- and -6 secretion systems and their effectors, and toxin genes, including exotoxin A. Both isolates A and B were resistant to colistin and harbored the mobile colistin resistance-3 (mcr-3) gene. Empirical therapy tailored to local Aeromonas antibiograms may facilitate more favorable outcomes, while advanced diagnostic methods may aid in identifying correct Aeromonas spp. of significant clinical importance.

A predictive algorithm for the analysis of AMR trends and healthcare decision support

Background Translating available AMR surveillance data to observe evolving patterns of microbial resistance to antimicrobial agents while identifying regions at high risk of resistant cases and serving as a decision-support tool is an aspect of AMR surveillance that is rarely explored nationwide and uncommon globally. Therefore, we developed a two-tier dashboard algorithm (PATHFINDER) that can analyse antimicrobial surveillance datasets, observe evolving global spatiotemporal patterns of AMR, and integrate local AMR gene resources to identify functional AMR determinant genes and antibiotic classes from the query organism genome. Methods The Python-based plotly library was used to develop the interactive variables of the Antimicrobial Testing Leadership Surveillance (ATLAS) dataset in an adjustable spatiotemporal environment. A lightweight database containing multiple known resistant genes from the ResFinder database was used as a prototype to identify unique AMR determinant genes from query nucleotide sequences. In R, a function was created to accept query genome sequences and generate Kmers of length 250 using the blaster package. The GPT-4 API plug-in was embedded with adequate prompt parsing for it as an interpretation LLM function. Results AMR trendline plots were designed for invasive infections and customised based on the class of antibiotics and infection types on the surveillance dashboard. The decision-support tool correctly predicted resistant genes with a sensitivity of 75% on pre-confirmed organisms. The observed specificity score (51.5%) was due to the need for more filtering and optimisation and not to PATHFINDER performance. When run against the reference gene dataset containing pre-identified AMR genes, the support tool generated a BLAST table with identified AMR gene determinants in a nucleotide sequence. Conclusions The PATHFINDER algorithm has the potential to revolutionise healthcare decision-making. It can inform targeted interventions, guide antimicrobial stewardship efforts at a national level, promote appropriate antibiotic use, and significantly reduce the risk of resistance development.

Molecular epidemiology and antimicrobial resistance profiles of Klebsiella pneumoniae isolates from hospitalized patients in different regions of China

IntroductionThe increasing incidence of Klebsiella pneumoniae and carbapenem-resistant Klebsiella pneumoniae (CRKP) has posed great challenges for the clinical anti-infective treatment. Here, we describe the molecular epidemiology and antimicrobial resistance profiles of K. pneumoniae and CRKP isolates from hospitalized patients in different regions of China.MethodsA total of 219 K. pneumoniae isolates from 26 hospitals in 19 provinces of China were collected during 2019–2020. Antimicrobial susceptibility tests, multilocus sequence typing were performed, antimicrobial resistance genes were detected by polymerase chain reaction (PCR). Antimicrobial resistance profiles were compared between different groups.ResultsThe resistance rates of K. pneumoniae isolates to imipenem, meropenem, and ertapenem were 20.1%, 20.1%, and 22.4%, respectively. A total of 45 CRKP isolates were identified. There was a significant difference in antimicrobial resistance between 45 CRKP and 174 carbapenem-sensitive Klebsiella pneumoniae (CSKP) strains, and the CRKP isolates were characterized by the multiple-drug resistance phenotype.There were regional differences among antimicrobial resistance rates of K. pneumoniae to cefazolin, chloramphenicol, and sulfamethoxazole,which were lower in the northwest than those in north and south of China.The mostcommon sequence type (ST) was ST11 (66.7% of the strains). In addition, we detected 13 other STs. There were differences between ST11 and non-ST11 isolates in the resistance rate to amikacin, gentamicin, latamoxef, ciprofloxacin, levofloxacin, aztreonam, nitrofurantoin, fosfomycin, and ceftazidime/avibactam. In terms of molecular resistance mechanisms, the majority of the CRKP strains (71.1%, 32/45) harbored blaKPC-2, followed by blaNDM (22.2%, 10/45). Strains harboring blaKPC or blaNDM genes showed different sensitivities to some antibiotics.ConclusionOur analysis emphasizes the importance of surveilling carbapenem-resistant determinants and analyzing their molecular characteristics for better management of antimicrobial agents in clinical use.

Sensitive and rapid identification of pathogens by droplet digital PCR in a cohort of septic patients: a prospective diagnostic study

Background There is a critical need for a rapid and sensitive pathogen detection method for septic patients. This study aimed to investigate the diagnostic efficacy of Digital droplet polymerase chain reaction (ddPCR) in identifying pathogens among suspected septic patients. Methods We conducted a prospective pilot diagnostic study to clinically validate the multiplex ddPCR panel in diagnosing suspected septic patients. A total of 100 sepsis episodes of 89 patients were included in the study. Results In comparison to blood culture, the ddPCR panel exhibited an overall sensitivity of 75.0% and a specificity of 69.7%, ddPCR yielded an additional detection rate of 17.0% for sepsis cases overall, with a turnaround time of 2.5 h. The sensitivity of ddPCR in the empirical antibiotic treatment and the non-empirical antibiotic treatment group were 78.6% versus 80.0% (p > 0.05). Antimicrobial resistance genes were identified in a total of 13 samples. Whenever ddPCR detected the genes beta-lactamase-Klebsiella pneumoniae carbapenemase (blaKPC) or beta-lactamase-New Delhi metallo (blaNDM), these findings corresponded to the cultivation of carbapenem-resistant gram-negative bacteria. Dynamic ddPCR monitoring revealed a consistent alignment between the quantitative ddPCR results and the trends observed in C-reactive protein and procalcitonin levels. Conclusions Compared to blood culture, ddPCR exhibited higher sensitivity for pathogen diagnosis in suspected septic patients, and it provided pathogen and drug resistance information in a shorter time. The quantitative results of ddPCR generally aligned with the trends seen in C-reactive protein and procalcitonin levels, indicating that ddPCR can serve as a dynamic monitoring tool for pathogen load in septic patients.

First Pangenome of Corynebacterium rouxii, a Potentially Toxigenic Species of Corynebacterium diphtheriae Complex

First Pangenome of Corynebacterium rouxii, a Potentially Toxigenic Species of Corynebacterium diphtheriae Complex

Genetic and virulence characteristics of hybrid Shiga toxin-producing and atypical enteropathogenic Escherichia coli strains isolated in South Korea

IntroductionThe predominant hybrid pathogenic E. coli, enterohemorrhagic E. coli (EHEC), combines characteristics of Shiga toxin-producing E. coli (STEC) and enteropathogenic E. coli (EPEC), contributing to global outbreaks with severe symptoms including fatal consequences. Since EHEC infection was designated as a notifiable disease in 2000 in South Korea, around 2000 cases have been reported, averaging approximately 90 cases annually.AimIn this work, genome-based characteristic analysis and cell-based assay of hybrid STEC/aEPEC strains isolated from livestock feces, animal source foods, and water in South Korea was performed.MethodsTo identify the virulence and antimicrobial resistance genes, determining the phylogenetic position of hybrid STEC/aEPEC strains isolated in South Korea, a combination of real-time PCR and whole-genome sequencing (WGS) was used. Additionally, to assess the virulence of the hybrid strains and compare them with genomic characterization, we performed a cell cytotoxicity and invasion assays.ResultsThe hybrid STEC/aEPEC strains harbored stx and eae genes, encoding Shiga toxins and E. coli attachment/effacement related protein of STEC and EPEC, respectively. Furthermore, all hybrid strains harbored plasmid-carried enterohemolysin(ehxCABD), a key virulence factor in prevalent pathogenic E. coli infections, such as diarrheal disease and hemolytic-uremic syndrome (HUS). Genome-wide phylogenetic analysis revealed a close association between all hybrid strains and specific EPEC strains, suggesting the potential acquisition of Stx phages during STEC/aEPEC hybrid formation. Some hybrid strains showed cytotoxic activity against HeLa cells and invasive properties against epithelial cells. Notably, all STEC/aEPEC hybrids with sequence type (ST) 1,034 (n = 11) exhibited higher invasiveness than those with E2348/69. This highlights the importance of investigating potential correlations between STs and virulence characteristics of E. coli hybrid strains.ConclusionThrough genome-based characterization, we confirmed that the hybrid STEC/aEPEC strains are likely EPEC strains that have acquired STEC virulence genes via phage. Furthermore, our results emphasize the potential increased danger to humans posed by hybrid STEC/aEPEC strains isolated in South Korea, containing both stx and eaeA, compared to STEC or EPEC alone.

Modelling the impact of wastewater flows and management practices on antimicrobial resistance in dairy farms

Dairy slurry is a major source of environmental contamination with antimicrobial resistant genes and bacteria. We developed mathematical models and conducted on-farm research to explore the impact of wastewater flows and management practices on antimicrobial resistance (AMR) in slurry. Temporal fluctuations in cephalosporin-resistant Escherichia coli were observed and attributed to farm activities, specifically the disposal of spent copper and zinc footbath into the slurry system. Our model revealed that resistance should be more frequently observed with relevant determinants encoded chromosomally rather than on plasmids, which was supported by reanalysis of sequenced genomes from the farm. Additionally, lower resistance levels were predicted in conditions with lower growth and higher death rates. The use of muck heap effluent for washing dirty channels did not explain the fluctuations in cephalosporin resistance. These results highlight farm-specific opportunities to reduce AMR pollution, beyond antibiotic use reduction, including careful disposal or recycling of waste antimicrobial metals.

WGS of intrauterine E. coli from cows with early postpartum uterine infection reveals a non-uterine specific genotype and virulence factors.

Escherichia coli has been attributed to playing a major role in a cascade of events that affect the prevalence and severity of uterine disease in cattle. The objectives of this project were to (i) define the association between the prevalence of specific antimicrobial resistance and virulence factor genes in E. coli with the clinical status related to uterine infection, (ii) identify the genetic relationship between E. coli isolates from cows with diarrhea, with mastitis, and with and without metritis, and (iii) determine the association between the phenotypic and genotypic antimicrobial resistance identified on the E. coli isolated from postpartum cattle. Bacterial isolates (n = 148) were obtained from a larger cross-sectional study. Cows were categorized into one of three clinical groups before enrollment: metritis, cows with purulent discharge, and control cows. For genomic comparison, public genomes (n = 130) from cows with diarrhea, mastitis, and metritis were included in a genome-wide association study, to evaluate differences between the drug classes or the virulence factor category among clinical groups. A distinct E. coli genotype associated with metritis could not be identified. Instead, a high genetic diversity among the isolates from uterine sources was present. A virulence factor previously associated with metritis (fimH) using PCR was not associated with metritis. There was moderate accuracy for whole-genome sequencing to predict phenotypic resistance, which varied depending on the antimicrobial tested. Findings from this study contradict the traditional pathotype classification and the unique intrauterine E. coli genotype associated with metritis in dairy cows.IMPORTANCEMetritis is a common infectious disease in dairy cattle and the second most common reason for treating a cow with antimicrobials. The pathophysiology of the disease is complex and is not completely understood. Specific endometrial pathogenic Escherichia coli have been reported to be adapted to the endometrium and sometimes lead to uterine disease. Unfortunately, the specific genomic details of the endometrial-adapted isolates have not been investigated using enough genomes to represent the genomic diversity of this organism to identify specific virulence genes that are consistently associated with disease development and severity. Results from this study provide key microbial ecological advances by elucidating and challenging accepted concepts for the role of Intrauterine E. coli in metritis in dairy cattle, especially contradicting the existence of a unique intrauterine E. coli genotype associated with metritis in dairy cows, which was not found in our study.

Multi-omics strategy reveals potential role of antimicrobial resistance and virulence factor genes responsible for Simmental diarrheic calves caused by Escherichia coli.

Escherichia coli (E. coli) is reported to be an important pathogen associated with calf diarrhea. Antibiotic resistance genes (ARGs) and virulence factor genes (VFGs) pose a considerable threat to both animal and human health. However, little is known about the characterization of ARGs and VFGs presented in the gut microbiota of diarrheic calves caused by E. coli. In this study, we used multi-omics strategy to analyze the ARG and VFG profiles of Simmental calves with diarrhea caused by E. coli K99. We found that gut bacterial composition and their microbiome metabolic functions varied greatly in diarrheic calves compared to healthy calves. In total, 175 ARGs were identified, and diarrheal calves showed a significantly higher diversity and abundance of ARGs than healthy calves. Simmental calves with diarrhea showed higher association of VFGs with pili function, curli assembly, and ferrienterobactin transport of E. coli. Co-occurrence patterns based on Pearson correlation analysis revealed that E. coli had a highly significant (P < 0.0001) correlation coefficient (>0.8) with 16 ARGs and 7 VFGs. Metabolomics analysis showed that differentially expressed metabolites in Simmental calves with diarrhea displayed a high correlation with the aforementioned ARGs and VFGs. Phylotype analysis of E. coli genomes showed that the predominant phylogroup B1 in diarrheic Simmental calves was associated with 10 ARGs and 3 VFGs. These findings provide an overview of the diversity and abundance of the gut microbiota in diarrheic calves caused by E. coli and pave the way for further studies on the mechanisms of antibiotic resistance and virulence in the calves affected with diarrhea.IMPORTANCESimmental is a well-recognized beef cattle breed worldwide. They also suffer significant economic losses due to diarrhea. In this study, fecal metagenomic analysis was applied to characterize the antibiotic resistance gene (ARG) and virulence factor gene (VFG) profiles of diarrheic Simmental calves. We identified key ARGs and VFGs correlated with Escherichia coli isolated from Simmental calves. Additionally, metabolomics analysis showed that differentially expressed metabolites in Simmental calves with diarrhea displayed a high correlation with the aforementioned ARGs and VFGs. Our findings provide an insight into the diversity and abundance of the gut microbiota in diarrheic calves caused by Escherichia coli and pave the way for further studies on the mechanisms of antibiotic resistance and virulence in the diarrheal calves from cattle hosts.

Impact of low-dose ozone nanobubble treatments on antimicrobial resistance genes in pond water

Impact of low-dose ozone nanobubble treatments on antimicrobial resistance genes in pond water

Genomic characterization of Aeromonas spp. isolates from striped catfish with motile Aeromonas septicemia and human bloodstream infections in Vietnam.

Aeromonas spp. are commonly found in the aquatic environment and have been responsible for motile Aeromonas septicemia (MAS) in striped catfish, resulting in significant economic loss. These organisms also cause a range of opportunistic infections in humans with compromised immune systems. Here, we conducted a genomic investigation of 87 Aeromonas isolates derived from diseased catfish, healthy catfish and environmental water in catfish farms affected by MAS outbreaks in eight provinces in Mekong Delta (years: 2012-2022), together with 25 isolates from humans with bloodstream infections (years: 2010-2020). Genomics-based typing method precisely delineated Aeromonas species while traditional methods such as aerA PCR and MALDI-TOF were unable identify A. dhakensis. A. dhakensis was found to be more prevalent than A. hydrophila in both diseased catfish and human infections. A. dhakensis sequence type (ST) 656 followed by A. hydrophila ST251 were the predominant virulent species-lineages in diseased catfish (43.7 and 20.7 %, respectively), while diverse STs were found in humans with bloodstream infections. There was evidence of widespread transmission of ST656 and ST251 on striped catfish in the Mekong Delta region. ST656 and ST251 isolates carried a significantly higher number of acquired antimicrobial resistance (AMR) genes and virulence factors in comparison to other STs. They, however, exhibited several distinctions in key virulence factors (i.e. lack of type IV pili and enterotoxin ast in A. dhakensis), AMR genes (i.e. presence of imiH carbapenemase in A. dhakensis), and accessory gene content. To uncover potential conserved proteins of Aeromonas spp. for vaccine development, pangenome analysis has unveiled 2202 core genes between ST656 and ST251, of which 78 proteins were in either outer membrane or extracellular proteins. Our study represents one of the first genomic investigations of the species distribution, genetic landscape, and epidemiology of Aeromonas in diseased catfish and human infections in Vietnam. The emergence of antimicrobial resistant and virulent A. dhakensis strains underscores the needs of enhanced genomic surveillance and strengthening vaccine research and development in preventing Aeromonas diseases in catfish and humans, and the search for potential vaccine candidates could focus on Aeromonas core genes encoded for membrane and secreted proteins.

Inferring diet, disease and antibiotic resistance from ancient human oral microbiomes.

The interaction between a host and its microbiome is an area of intense study. For the human host, it is known that the various body-site-associated microbiomes impact heavily on health and disease states. For instance, the oral microbiome is a source of various pathogens and potential antibiotic resistance gene pools. The effect of historical changes to the human host and environment to the associated microbiome, however, has been less well explored. In this review, we characterize several historical and prehistoric events which are considered to have impacted the oral environment and therefore the bacterial communities residing within it. The link between evolutionary changes to the oral microbiota and the significant societal and behavioural changes occurring during the pre-Neolithic, Agricultural Revolution, Industrial Revolution and Antibiotic Era is outlined. While previous studies suggest the functional profile of these communities may have shifted over the centuries, there is currently a gap in knowledge that needs to be filled. Biomolecular archaeological evidence of innate antimicrobial resistance within the oral microbiome shows an increase in the abundance of antimicrobial resistance genes since the advent and widespread use of antibiotics in the modern era. Nevertheless, a lack of research into the prevalence and evolution of antimicrobial resistance within the oral microbiome throughout history hinders our ability to combat antimicrobial resistance in the modern era.