Prevalence of toxigenic Clostridium botulinum in food products sold in Indian retail markets.

[INTRODUCTION] Clostridium botulinum and botulinum neurotoxins have been recognized as an important food safety hazard. The objective of this study was to screen the prevalence of C. botulinum and botulinum toxin in various food products sold in the retail markets of India.

[MATERIAL AND METHODS] A total of 236 food products collected from Indian retail markets were screened for preformed botulinum toxin using a mouse bioassay. This was followed by enrichment and isolation and further testing of isolates for botulinum toxin production using an additional mouse bioassay. A toxin neutralization test with type specific antitoxins, 16S rRNA gene sequencing and BoNT (botulinum neurotoxin) gene amplification confirmed the presence of C. botulinum and its toxin production potential.

[RESULTS AND DISCUSSION] Preformed botulinum toxin was not detected in any of the products. The overall prevalence of C. botulinum in the products was 11 %, but pure cultures of C. botulinum could be isolated only from 10 samples. The isolates were identified as C. botulinum type A, type B and type E based on toxin typing with type specific antitoxins and amplification of the botulinum neurotoxin (BoNT) gene. One of the isolates was designated as C. botulinum subtype AB. This is the first report of isolation of C. botulinum type E and subtype AB in seafood from India. The presence of C. botulinum in the products tested can be a significant public health hazard since the organism can grow when exposed to favourable conditions and can produce neurotoxin in the food.