Prevalence and antibiogram of Listeria monocytogenes isolated from ready-to-eat vegetables and fermented milk in Yola, Nigeria

Document Type : Original Article


1 Department of Microbiology, Modibbo Adama University of Technology, Yola, Nigeria

2 Department of Microbiology, MAU, Yola, Nigeria


Aim: Listeria monocytogenes (L. monocytogenes) has been reported as the major pathogen that contributes to foodborne illness. This study was conducted to determine the prevalence and to characterize Listeria monocytogenes isolated from ready to eat vegetables and local fermented milk (Nono) in Yola, Nigeria. Methods: A total of 162 samples of cabbage, lettuce, ready to eat salad and fermented milk were examined on PALCAM and Brilliance Listeria Agar. Results: Distribution of L. monocytogenes from the study showed that cabbage had the highest prevalence of 42.3% followed by lettuce with 26.9%. The least occurrence (11.5%) was obtained from fermented milk. Furthermore, L. monocytogenes occurrence was from vegetable obtained from shinko farm (53.9%) while least (19.2%). The total bacterial counts of the ready to vegetables and fermented milk from the study ranged from 6 x 103 cfu/ml to 1.86 x 105 cfu/g. The result also showed that cabbage had the highest contamination from all the study locations and fermented milk from all the study locations had the least total bacterial counts. Antimicrobial susceptibility screening of the isolates revealed that more than 60% of the isolates were susceptible to commonly used antibiotics. However, about 65% of the isolates demonstrated resistance to erythromycin and cotrimoxazole. Also, none of the isolates harbored any plasmids. Conclusion: Findings from this study are of public health significance as all the samples studied do not require cooking before they are consumed. Thus, there is need to exercise caution during purchase, processing and consumptions of these vegetables and milk.


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