Antimicrobial resistance and virulence factors profile of Salmonella spp. and Escherichia coli isolated from different environments exposed to anthropogenic activity

Objective: The study aimed to identify the antimicrobial resistance (AMR) determinants and virulence factors in Salmonella spp. and Escherichia coli recovered from different anthropogenic areas in North Carolina. Methods: Soil samples were collected from different anthropogenic areas, urban and natural. The minimum inhibitory concentration (MIC) was determined by using the broth microdilution method. Whole-genome sequencing (WGS) and analysis were done to identify the AMR determinants and virulence factors. Results: A higher prevalence of Salmonella spp. and E. coli was detected in the urban environment. The Salmonella spp. isolates showed resistance to sulfisoxazole and streptomycin, whereas E. coli was resistant to sulfisoxazole, cefoxitin and ampicillin. Salmonella serotypes Schwarzengrund and Mississippi were identified based on WGS analysis. Aminoglycoside resistance genes and IncFIB and IncFIC(FII) plasmids were detected among Salmonella spp. In general, E. coli was predominated by isolates from phylogroups B1, B2 and D. The multidrug transporter mdfA gene was detected in most of the E. coli from both the urban (100%) and natural (84.5%) environments. The FosA7 gene was detected in an isolate from a residential yard. The pCoo and pB171 plasmids were detected in an urban environment; col(156) and pHN7A8 plasmids were detected in natural environments. Conclusions: The detection of AMR determinants and virulence factors in these bacteria is significant in understanding the occurrence and even the development of AMR. The presence of these determinants in different anthropogenic areas suggests the need to conduct longitudinal studies for comparing the profile of pathogens across different environments.