Occurrence of Escherichia coli and screening for enteropathogenic virulence genes (eaeA, bfpA) in cattle and abattoir environments in Sagamu, Southwest Nigeria: a cross-sectional study

Background Pathogenic Escherichia coli , including enteropathogenic E. coli (EPEC), remains among the leading bacterial causes of diarrhoeal illness worldwide. Cattle and abattoir environments are widely recognised as reservoirs from which such organisms may be transmitted to humans through zoonotic contact or contamination of the food chain. Contemporary data on the occurrence of EPEC virulence determinants in cattle slaughtered in Nigerian abattoirs remain scarce. This study, conducted between September and November 2017, determined the prevalence of E. coli and screened isolates for the eaeA and bfpA virulence genes among cattle- and abattoir-associated samples in Sagamu, Ogun State, Nigeria. Methods A cross-sectional study was conducted from September to November 2017 at two cattle abattoirs (Kara and Agbele) in Sagamu. Samples of faeces, hair and skin (brisket and rump regions), and slaughterhouse floor swabs were cultured on MacConkey and Eosin Methylene Blue agar. Presumptive E. coli colonies were confirmed biochemically using the BD BBL Crystal Enteric/Non-fermenter Identification System. Genomic DNA was extracted from confirmed isolates and screened by conventional PCR for the eaeA and bfpA genes. Proportions were summarised with Wilson score 95% confidence intervals (CI); between-abattoir comparisons used Fisher’s exact test because expected cell counts were below five in several strata. Results Of 108 samples processed, 50 (46.3%; 95% CI 37.2–55.7%) yielded E. coli confirmed by biochemical profiling. Occurrence did not differ significantly between the Kara (26/54, 48.1%) and Agbele (24/54, 44.4%) abattoirs (Fisher’s exact p = 0.847). Faecal and brisket-skin samples showed the highest recovery (65.0% each; 95% CI 43.3–81.9%), while no E. coli was recovered from slaughterhouse floor swabs taken before or after use. None of the 50 confirmed isolates carried the eaeA or bfpA gene (0/50; 95% CI 0.0–7.1%), indicating an absence of detectable typical or atypical EPEC among the isolates screened, although the upper confidence bound cannot exclude a low true prevalence. Conclusions Cattle and carcass-contact surfaces at the two abattoirs studied carried a substantial burden of E. coli , but no eaeA - or bfpA -positive EPEC was detected within the limits of this study’s sample size and two-gene screening panel. These findings should be interpreted as abattoir- and time-point-specific rather than as evidence of an EPEC-free status for cattle across the wider Sagamu area or Nigeria. Larger, multi-site, multi-seasonal studies incorporating a broader diarrhoeagenic E. coli gene panel, serotyping and antimicrobial susceptibility testing are needed to fully characterise the zoonotic and food-safety risk posed by abattoir-associated E. coli in this setting. Clinical trial number Not applicable.