Sorbitol non-fermenting Escherichia coli and E. coli O157: prevalence and antimicrobial resistance profile of strains in slaughtered food animals in Southeast Nigeria

Abstract

Antimicrobial resistance (AMR) is one of the greatest global health challenges. Reliable monitoring of AMR in bacteria in food animals is critical in order to devise mitigation strategies and empiric treatment of infections associated with the organisms. The aim of this study was to isolate sorbitol non-fermenting (SN-F) Escherichia coli from food animals (broiler chickens, cattle and pigs) slaughtered at Ikpa Market, Nsukka, Enugu State, Southeast Nigeria, detect E. coli O157 and determine the in vitro antimicrobial resistance profile of the E. coli strains. A total of 388 faecal samples were collected from randomly selected broiler chickens (n=155), cattle (n=129) and pigs (n=104). Isolation of SN-F E. coli was done using tryptic soy broth and cefixime- and potassium tellurite-supplemented sorbitol MacConkey agar (CT-SMAC). SN-F E. coli strains were confirmed biochemically and E. coli O157 detected serologically using specific E. coli O157 latex agglutination test kit. The antimicrobial resistance profile of all strains was established using the disc diffusion method. Overall, 52 (13.4 %) SN-F E. coli strains were recovered from the broiler chickens (n=31), cattle (n=12) and pigs (n=9). A significant association (χ2=9.70; P <0.05) was observed between the prevalence of SN-F E. coli and animal species. E. coli O157 was detected in two of the samples, representing 0.51% of the 388 samples processed. All the E. coli strains were resistant to at least one antimicrobial agent tested and 76% were multidrug resistant (MDR). The mean multiple antibiotic resistance indices (MARI) for isolates from chickens, cattle and pig were 0.32, 0.18 and 0.23, respectively. This study showed that a considerable percentage of food animals slaughtered in Nsukka Southeastern Nigeria are potential reservoirs of multiple-drug-resistant SN-F E. coli, including E. coli O157 that could spread to humans and the environment.