Biology subjects

Sahibzada, S.

Publications and source records attributed to Sahibzada, S..

2 recordsLinked to original sources

bioRxiv2022

Antimicrobial Resistance, Genomic, and Public Health Insights into Enterococcus spp. from Australian Cattle

Enterococci are opportunistic, potentially life-threatening pathogens of humans that are difficult to manage due to antimicrobial resistance. Historically, enterococci entering the food-chain through livestock have been viewed as a likely source of antimicrobial resistance in humans. Australian human-derived clinical enterococci have a propensity to be resistant to multiple classes of antimicrobials including vancomycin. Recent Australian studies involving pigs and chicken have virtually excluded these species as reservoirs of infection for resistant enterococci in humans. However, the Australian bovine population has not been similarly assessed. This study investigates the antimicrobial resistance profiles of enterococci from Australian cattle and the phylogenetic relationship between E. faecium isolated from cattle and human sepsis cases. Minimum inhibitory concentration assays were performed for E. faecium (n=343), E. faecalis (n=92), and E. hirae (n=284) against a panel of 15 antimicrobials. The majority of isolates were sensitive to all tested antimicrobials. Erythromycin resistance was most prevalent for E. faecium isolates (18.7%), daptomycin for E. faecalis (12.1%) and tetracycline for E. hirae (13.3%). Phenotypically, 1 E. faecalis was resistant to vancomycin and 9 were resistant to linezolid (E. faecium n=4, E. faecalis n=2, E. hirae n=3) but this was not confirmed with any know genotype. A subset of 67 E. faecium isolates selected for comparative phylogenetic analysis revealed that bovine isolates clustered with other livestock-derived and van-negative human isolates. In conclusion, there is a low prevalence of antimicrobial resistance amongst enterococci from Australian cattle which are unlikely to be precursor strains to vancomycin-resistant strains currently circulating in Australian hospitals. ImportanceEnterococci resistant to critically important antimicrobials such as vancomycin and linezolid are difficult to manage in health care settings. Historically, there has been the belief that livestock can act as a reservoir of resistance for human infections. Previous studies in poultry and pork have demonstrated that isolates derived from these livestock are unlikely to be precursor strains for currently circulating vancomycin resistant-Enterococci causing infection in humans. To date, there has been no study looking at the genetic similarity of bovine derived Enterococci and the relationship to human pathogenic strains. In this study we performed phenotypic and genotypic characterization of bovine derived Enterococci along with comparative phylogenetic analysis with other livestock derived and human sepsis derived E. faecium isolates. We found that while non-vancomycin resistant strain sharing occurs between hosts, cattle are unlikely to be precursor strains for vancomycin resistant human E. faecium infections.

microbiology↗

bioRxiv2021

Proximity to human settlement is directly related to carriage of critically important antimicrobial-resistant Escherichia coli and Klebsiella pneumoniae in Silver Gulls

Human population and activities play an important role in dissemination of antimicrobial resistant bacteria. This study investigated the relationship between carriage rates of critically important antimicrobial-resistant (CIA-R) Escherichia coli and Klebsiella pneumoniae by Silver Gulls and their proximity to human populations. Faecal swabs (n=229) were collected from Silver Gulls across 10 southern coastline locations in Western Australia (WA). The sampling locations included main town centres and remote areas. Fluoroquinolone and extended-spectrum cephalosporin-resistant E. coli and K. pneumoniae were isolated and tested for antimicrobial sensitivity. Genome sequencing was performed to validate phenotypic resistance profiles and determine the molecular characteristics of strains. CIA-R E. coli and K. pneumoniae were detected in 69 (30.1%) and 20 (8.73%) of the faecal swabs respectively. Two large urban locations tested positive for CIA-R E. coli (frequency ranging from 34.3%-84.3%), and/or for CIA-R K. pneumoniae (frequency ranging from 12.5%-50.0%). A small number of CIA-R E. coli (3/31, 9.7%) were identified at a small tourist town, but no CIA-R bacteria were recovered from gulls at remote sites. Commonly detected E. coli sequence types (STs) included ST131 (12.5%) and ST1193 (10.0%), and five K. pneumoniae STs were found. Resistance genes including blaCTX-M-3, blaCTX-M-15 and blaCTX-M-27 were identified in both bacterial species. High-level colonisation of CIA-R E. coli and K. pneumoniae in Silver Gulls in and around urban areas compared to remote locations substantiates that anthropogenic activities are strongly associated with acquisition of resistant bacteria by gulls. ImportanceHumans play an important role in dissemination of antimicrobial resistant bacteria. This study investigated the relationship between carriage rates of resistant bacterial pathogens (Escherichia coli and Klebsiella pneumoniae) among Silver Gulls and their proximity to human populations. The frequency of resistant E. coli carriage was high (ranging from 34.3 - 84.3%) in the samples collected from areas with high human population density while resistant K. pneumoniae frequencies at these sites varied from 0 to 50%. However, resistant E. coli and K. pneumoniae were not recovered from any of the remote sites that did not have a permanent human population. This study, conducted across a large stretch of the southwestern Australian coastline, indicated that seagulls act as vectors in carrying and disseminating antimicrobial resistant bacteria, including clinically significant strains. High-level colonisation of resistant E. coli and K. pneumoniae in Silver Gulls in and around urban areas compared to remote locations substantiates that human activities are strongly associated with acquisition of resistant bacteria by Silver gulls.

microbiology↗