Occurrence of clostridia in glass bottled foods

Forty-one marketed samples of imported and domestic glass bottled foods were tested for clostridia contamination. It was detected in nine (22%) samples. Clostridia were isolated from fish sauce (Nam pla, Nuoc-mam), dressing, mustard, hot and sour soup mix (Tom Yum), mysids boiled down in soy, and salmon flakes. The origin of all clostridia positive samples was Asia. Clostridium botulinum and C. perfringens were not detected. The frequency of occurrence was higher by enrichment broth culture detection methods than by agar plate or pouch methods. These findings suggest that the number of bacteria in most of these clostridia positive food samples is very low, and the use of enrichment methods for detection of clostridia is essential.