Dissemination of Extended-Spectrum Beta-Lactamases producing Escherichia coli in poultry in Zimbabwe

Extended-spectrum beta-lactamase (ESBL) producing Escherichia coli are resistant to the critically important third and fourth generation cephalosporin antibiotics and present a risk to animal and human health. In Zimbabwe there is an evidence gap concerning the prevalence and diversity of ESBL-producing E. coli in poultry. In this study we screened for ESBL-E. coli at farms (n=50) and markets (n=10), according to ISO standards. Seventy ESBL-E. coli were obtained and examined by antimicrobial susceptibility testing and whole genome sequencing. Geographic Information System mapping was used to visualise the distribution of the ESBL-producing clones. A total of eight distinct blaCTX-M variants were identified and all were multidrug resistant. Genomic analysis revealed evidence for clonal expansion of an ESBL-producing clone and horizontal gene transfer via plasmids being responsible for the dissemination of ESBL-E. coli. For example, ST1141 isolates were clonal, having a highly conserved core genome, and harboured blaCTX-M-15 and 11 additional antimicrobial resistance genes on a ~338kbp IncHI2 plasmid which was not present in other isolates. This clone was present at nine farms. In contrast, a conserved ~93kpb IncFII plasmid harbouring blaCTX-M-55 was present in isolates from three different Multilocus Sequence Types obtained from six farms. This study underscores the importance of adopting measures that can limit the development and dissemination of ESBL-producing E. coli. Findings highlight the need for One Health approaches, such as improved biosecurity and WASH measures, and reinforce the call for policies on appropriate antibiotic use livestock setting to reduce AMR transmission risks to humans.