Food Microbiology

Street foods are common in Nigeria serving the purposes of supplementing family income and meeting food demands of low income urban dwellers. However, these foods can become vehicles for transmitting food-borne pathogens due to poor processing and handling. This study is aimed at assessing the bacteriological safety of three foods [‘abacha’ (African salad), roasted pork and ‘ukwa’ (Treculia africana)] commonly vended in Owerri, Nigeria. Twelve samples [four each of ‘abacha’, roasted pork and ‘ukwa’] were purchased from different vendors in Owerri metropolis. Bacterial were isolated from the food samples by the pour plate method on nutrient, MacConkey, eosin methylene blue and Salmonella-Shigella agar plates and characterized using a combination of cultural/biochemical and 16S rRNA sequencing technologies. The antibiotic susceptibility test was performed for each isolate by the disk diffusion method. Plasmid profiles of isolates resistant to four or more antibiotics were determined followed by plasmid curing and a repeat of antibiotic susceptibility test to indicate whether resistance is chromosomal or carried on a mobile element. Thirty- one isolates comprising seven species [Acinetobacter baumannii, Bacillus sp., Enterobacter sp., Escherichia coli, Klebsiella sp., Kurthia gibsonii and Salmonella sp.] were obtained from the food samples. ‘Ukwa’ showed the highest microbial load and multi drug resistance was observed in 11 (35.5%) of the isolates, seven of which harboured plasmids ranging 0.5-48.5 kb. Plasmid curing improved sensitivity of isolates to all antibiotics except ampicillin and nalidixic acid. The presence of pathogens and multi drug resistant isolates in these street foods renders them unsafe for human consumption.