Bacteria associated with contamination of ready-to-eat (RTE) cooked rice in Lagos-Nigeria

Abstract

The bacteria associated with contamination of ready-to-eat (RTE) cooked rice in Lagos, Nigeria were studied using standard microbiological methods. The objective of this study was to investigate the distribution of pathogenic bacteria recovered from RTE cooked rice in Lagos, assess bacteria load in the contaminated RTE cooked rice and evaluate their microbial quality. The microbial load of the RTE cooked rice ranged from 1.5 ± 0.29x 10⁴- 4.8 ± 0.46x 10⁶cfu/g for three markets. A further test revealed that the average bacteria counts at Ketu was significantly different from those at Yaba and Odogunyan. However it was found that counts at Yaba and Odogunyan were not significantly different. Based on the specification by the International Microbiological Standard limits for Foods (IMSF), the levels of contamination of the total samples that were above and below microbiological acceptable limit were 91.7% and 8.3% respectively. The predominant pathogenic bacteria associated with contamination of the RTE cooked rice samples were identified as Staphylococcus aureus, Brahamella sp, Enterobacter aerogenes and Salmonella typhi. Out of a total of 36 RTE cooked rice samples analyzed, Enterobacter aerogenes 36 (100%) had the highest occurrence followed in descending order by Staphylococcus aureus 33 (91.7%), Brahamella sp. 29 (80.6%) and Salmonella sp. 25(69%). The results indicated that most of the RTE cooked rice samples examined in this study did not meet bacteriological quality standards. These findings suggest that the presence of food pathogens in RTE rice hawked in our local markets may pose serious potential health risks to the consumers in the public.
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Keywords: Contamination, pathogenic, bacteria, ready-to-eat (RTE), cooked rice