Safety and quality evaluation of street foods sold in Zaria, Nigeria

Ready-to-eat foods and beverages were purchased from street food sellers in Zaria, Nigeria for microbiological analysis. Total aerobic organisms were cultured on plate count agar, Staphylococcus aureus was isolated on Baird Parker agar, Bacillus cereus on mannitol-egg yolk-polymyxin agar and Salmonella on Salmonella-Shigella agar after enrichment in tetrathionate broth. The mean aerobic counts for the food from mobile food sellers (MS), stationary food sellers without shelter (SWS) and stationary food sellers with shelter (SS) were not significantly different from one another except for 'kunu' and 'moin-moin' with counts ranging from 3.67 +/- 0.4 log(10)/g to 4.29 +/- 1.14 log(10)/g for 'kunu' and 2.84 +/- 0.55 log(10)/g to 4.7 +/- 0.84 log(10)/g for 'moin-moin'. However, all the counts were lower than the permissible level of count (5.0 log(10)/g) for cooked foods. Out of 160 food samples tested, 42 (26.3%) were contaminated with B. cereus, 24 (15.9%) with S. aureus. Six (18.3%) of the 32 coagulase positive S. aureus isolates tested produced enterotoxin A (SEA). More than 50% of the coagulase positive S. aureus were resistant to the common antimicrobial drugs used in the treatment of staphylococcal and wound infections. None of the samples from MS were contaminated with S. aureus and no Salmonella was isolated from all the samples. Samples from SWS had the highest frequency of contamination with B. cereus and S. aureus. Education of the street food handlers and the public on environmental sanitation and safe food handling practices is recommended. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.