Microbiological Analysis and Antimicrobial Susceptibility Pattern of Salmonella typhi and Escherichia coli Isolated from Raw Vegetables Sold in Some Selected Markets in Damaturu, Potiskum and Bade L.G.A, Yobe State, Nigeria

The contamination of vegetables by pathogenic microorganisms is a global challenge to food safety and human health. This study was carried out to isolate Salmonella typhi and Escherichia colion three different raw vegetables (tomato, lettuce and carrot) randomly sampled from central markets (Damaturu, Potiskum and Bade) in Yobe State, Northeast, Nigeria. A total of two hundred and seventy (270) raw vegetable samples; (30) tomatoes, (30) lettuce and (30) carrots from each market were collected in clean-sterilized sampling bag and taken to Microbiology Laboratory, Department of Microbiology, Yobe State University Damaturu, Nigeria, for the isolation of S. typhi and E. coli using standard laboratory protocol. One hundred and thirty-six (136) positive isolates; Sixty-seven (67) S. typhi and sixty-nine (69) E. coli were obtained from raw vegetables. Damaturu market S. typhi were high in lettuce 47.1%, tomato 41.7% and carrot 37.5% while the E. coli has highest percentage on carrot 62.5%, tomato 58.3% and lettuce 52.9%. In Potiskum market, S. typhi occur higher on lettuce 57.7%, carrot 56.3% and tomato 42.9% while E. coli has high percentage on tomato 57.1%, carrot 43.7% and lettuce 42.3%. In Gashua (Bade) market, S. typhi has high occurrence on lettuce 54.5%, tomato 45.5% and carrot 40.0% while E. coli has highest occurrence in carrot 60.0%, tomato 54.5% and lettuce 45.5% respectively. The antibiotic sensitivity test of the resistant isolates (S. typhi and E. coli) shows one hundred and thirty-six (136) were isolated, thirty-seven (37) resistant isolates in Damaturu, fifty-six (56) in Potiskum and forty-five (45) in Gashua markets. The resistant genes were observed using an agarose gel electrophoresis of amplified 16SrRNA gene for S. typhi at 500bp and 586bp for E. coli were detected. The high presence of the resistant isolatesin raw vegetablesindicates contamination of faecal origin probability during harvesting, processing, selling and/or distribution under inadequate hygienic conditions. Surveillance and enlightenment were recommended to the general public on the health risk of consuming unhygienic raw vegetables. Keywords: Salmonella spp., Escherichia coli, Enterobacteriaceae, Raw vegetables, Antibiotic resistance, Food safety, public health.