Occurrence and Virulence Gene Profiles of Enterohaemorrhagic Escherichia Coli O157:H7 Isolated from Cattle at Abattoirs in the Federal Capital Territory, Nigeria
Enterohaemorrhagic (EHEC) Escherichia coli O157:H7 is an important foodborne zoonotic pathogen carried asymptomatically by cattle and capable of causing severe disease in humans. This study investigated the occurrence and virulence gene profiles of (EHEC) E. coli O157:H7 isolated from cattle at selected abattoirs in the Federal Capital Territory (FCT), Nigeria. A total of 450 rectal swab samples were collected from cattle slaughtered at five major abattoirs (Dei-Dei, Gwagwalada, Kubwa, Karu, and Guzape). Isolation was carried out using standard bacteriological techniques, followed by biochemical confirmation and serological identification using O157 latex agglutination and H7 flagellar antigen tests. Genomic DNA was extracted from confirmed isolates using the QIAGEN DNA extraction kit, and multiplex polymerase chain reaction (PCR) was performed to detect the eaeA, hlyA, rfbE, and fliCH7 virulence genes. Overall, E. coli was isolated from 175 (38.9%) samples. Of the 28 presumptive isolates selected for confirmation, 18 (64.3%) were biochemically confirmed as E. coli, while 8 (44.4%) possessed the O157 antigen. From the total E. coli, 18 (4%) were suspected O157 colonies on Sorbitol MacConkey Agar. Following O157 latex agglutination, 8 (1.78%) were positive, H7 flagellar agglutination shows 5 (1.11%) and EHEC result shows 2 (0.44%). Molecular characterization demonstrated the presence of the targeted virulence genes among the confirmed E. coli O157 isolates, confirming their pathogenic potential. The occurrence of EHEC E. coli O157:H7 did not differ significantly among the sampled abattoirs (Fisher-Freeman-Halton exact test, p > 0.05). The findings demonstrate that cattle slaughtered in FCT abattoirs constitute a reservoir of pathogenic E. coli O157:H7 and underscore the need for strengthened abattoir hygiene, routine microbiological surveillance, and integrated One Health interventions to reduce contamination of beef and the risk of zoonotic transmission.
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