PS4-26. Prevalence, Antimicrobial Resistance Profiles, and Genomic Determinants of Enterobacter Hormaechei and Escherichia coli Isolated from Communally Grazed Cattle in South Africa.

Abstract Antimicrobial resistance is an increasing global health issue of human, animal, and environmental health in the One Health paradigm. Food-producing animals are believed to be one of the main sources of antimicrobial-resistant bacteria and resistance plasmids that could be transferred to the food chain, environmental routes, and direct animal-human contact. The paper has looked at the prevalence, antimicrobial resistance, and genomic resistance determinant of Escherichia coli and Enterobacter hormaechei in fecal samples of cattle grazing in the village of Mogosane, North-West Province, South Africa. A total of thirty-five rectal fecal samples that appeared healthy in cattle were collected and tested using standard microbiological culture and biochemical identification systems. Antimicrobial susceptibility was conducted using the Kirby-Bauer disk diffusion technique with 10 generally used antibiotics, and the results were interpreted following the Clinical and Laboratory Standards Institute (CLSI. 2020). Whole-genome sequencing of selected antimicrobial-resistant isolates was performed on the Illumina HiSeq X platform, and genome assemblies were generated with SPAdes, followed by annotation using the NCBI Prokaryotic Genome Annotation Pipeline. Out of three isolated E. coli (9%) and twelve E. hormaechei (34%) were obtained out of the sampled population. E. coli isolates were all resistant to streptomycin and erythromycin, and E. hormaechei isolates were resistant to ampicillin and erythromycin primarily. E. hormaechei isolates that exhibited multidrug resistance were found in 33% of them. Multidrug efflux pump genes (acrA, acrB, and marA), aminoglycoside resistance gene (aphA), and ribosomal mutation gene (rpsL) were identified by whole-genome sequencing, suggesting the presence of multiple resistance mechanisms. These results indicate that antimicrobial-resistant Enterobacteriaceae are present in communal cattle production systems and suggest that livestock may act as reservoirs of resistance genes. Offering valuable insights into the dynamics of antimicrobial resistance in rural livestock environments, the combination of phenotypic resistance profiling and genomic characterization underscores the need to improve genomic surveillance and antimicrobial stewardship programs as part of AMR One Health-based monitoring programs.