C. R. Reuben, E.C. Okolocha, M. Bello, H. Tanimu
Abstract: Escherichia coli O157:H7 is a newly emerging pathogen frequently associated with the consumption of food of bovine origin. Severe and life threatening human diseases caused by E. coli O157:H7 strains have been reported throughout the world. This present study evaluated the occurrence of E. coli O157:H7 in locally-fermented milk (nono) sold under market conditions in Nasarawa State, Nigeria and the patterns of their antibiotic susceptibility. A total of 420 nono samples were purchased across Nasarawa State. The samples were bacteriologically analyzed in the laboratory for the presence of E. coli O157:H7 by means of cultural techniques (enrichment on modified tryptone soy broth and selective plating on Cefixime-Tellurite Sorbitol Mac-Conkey Agar), biochemical (Microbact 12E) and serological assays. Oxoid diagnostic kit; latex (R30959601) was used to confirm E. coli O157:H7 respectively. Confirmed isolates were further subjected to antimicrobial susceptibility test using the Agar disc diffusion technique. The results of the study showed that out of 420 nono samples examined, 19 (4.5%) were contaminated with E. coli O157:H7. Among samples examined, the highest occurrence rate (5.7%) was recorded in samples obtained from Akwanga, Wamba and Doma Local Government Areas while Lafia and Keffi had the least occurrence rate (2.9%). With respect to the senatorial zones, Nasarawa North had the highest occurrence rate of 5.7% while the Southern zone had the least (3.6%). There was no significant difference (P>0.05) in the occurrence of E. coli O157:H7 isolated from nono samples with respect to the various Local Government Areas. Antibiotics susceptibility profile showed that all the isolates were resistant to multiple antibiotics, except ciprofloxacin and gentamicin, resulting in nine different resistance patterns. All the nineteen (100%) of the isolates were resistant to penicillin and tetracycline, 18 (94.7%) to erythromycin, 16 (84.2%) to amoxicillin, oxacillin and sulphamethoxazole/trimethoprim, 13 (68.4%) to chloramphenicol and 8 (42.1%) to streptomycin. 15 (78.9%) and 17 (89.5%) of the isolates were sensitive to ciprofloxacin and gentamicin. The predominant antimicrobial resistance pattern was penicillin-tetracycline-chloramphenicol-amoxycilin-erythromycin-oxacillin-sulphamethoxazole/ trimethoprim with the occurrence rate of 36.8% from samples obtained from Wamba, Doma, Kokona and Keffi. Nono consumption has potential health risks to consumers in Nasarawa State, hence proper hygiene in the process-line and marketing of nono is recommended. The multiple antimicrobial resistance exhibited by E. coli O157:H7 strains in this study is an indication of possible antibiotic abuse.
Keywords: E. coli O157:H7, emerging, locally fermented milk, Antibiotics, resistance