Characterization of Escherichia coli O157:H7 from Cattle and Beef in Slaughterhouses in Borno State

Escherichia coli O157:H7 is an enterohemorrhagic pathogen of public health significance transmitted through contaminated beef. This study characterized E. coli O157:H7 from cattle and beef in slaughterhouses in Borno State, North East Nigeria. Rectal swabs from 200 slaughter cattle and carcass swabs from corresponding animals were collected over four months at two abattoirs in Maiduguri. Standard cultural methods including sorbitol MacConkey agar were used for initial isolation. Presumptive isolates were confirmed by polymerase chain reaction targeting the rfbO157 and fliCh7 genes. Positive isolates were tested for virulence gene profiles including stx1, stx2, and eaeA by multiplex PCR. Antimicrobial susceptibility was determined by disk diffusion. E. coli O157:H7 was isolated from 9% of rectal samples and 14.5% of carcass swabs, indicating contamination during slaughter. Virulence gene analysis revealed that 72.4% of isolates carried stx2, indicating high pathogenic potential. Multi-drug resistance was present in 55% of isolates, with ampicillin and tetracycline resistance most common. The study concludes that E. coli O157:H7 contamination of beef carcasses occurs at significant frequency during Borno State slaughter operations and that the virulent and drug-resistant profiles identified pose a serious public health risk. Hygienic slaughter improvements, carcass decontamination interventions, and active surveillance are urgently needed. Keywords: E. coli O157:H7, beef contamination, virulence genes, abattoir, Borno State