Distribution of Clostridium botulinum in soil, debris and water was examined in Toyama Prefecture for the purpose of preventing food poisoning due to this organism. The results obtained were as follows: Detection frequencies of C. botulinum from soil or debris decreased in the following order; pond (7/9, 78%), river (12/23, 52%), fishing port (2/20, 10%), rice field and vegetable garden (1/40, 2%). The toxin types detected were C1 (9 samples), C1+D (8), C1+C2 (2), C1+C2+D (2) and E (1). The main toxin in the cultures containing C1+C2 or C1+D was C1. The level of C1 toxin detected was the highest in pond among all cultures examined. C1 toxin was detected in December, February, April and June, but not in August or October, in cultures of the pond where wild ducks were seen during the winter season. These results indicate that the dominant type of C. botulinum distributed in Toyama Prefecture is Ca. This may be related wit the migration of wild ducks. Type D was less dominant and type E only rarely detected.
Experiments were carried out to find the most adequate incubation temperature for growing Salmonella in a combination of pre-enrichment and some selective enrichment culture. The results are as follows: Pre-enrichment for 18 h in EEM medium at 42°C as followed by growing for 20 h at 35°C in selective enrichment medium was most an efficient to isolate Salmonella from various meats (method III). In addition to method III, adoption of method II consisting of pre-enrichment for 18 h at 35°C and then growing for 20 h at 42°C in a selective medium further increased the rate of detection of Salmonella in meats.
Honey has served as a vehicle of Clostridium botulinum spores in infant botulism. The present study was designed to find the stability of the spores in honey during storage at different temperatures. When honey samples containing 104/g of type A (62A) or type B (Okra) spores were stored at 4°C, the spore population did not change over a year. At 25°C, however, the spores decreased in number gradually after 100 days. Only 1% of type A and none of type B spores were detected after 400 days of storage. None of such physico-chemical treatments as heat shock, sonication and treatment with detergent, enzyme, alcohol, acid and alkaline had significant effect on the botulinum spore population. Neither type A nor type B spores were detected after 5 days of storage at 65°C. Type B seemed to be more sensitive than type A spores. At this temperature, the honey deteriorated slightly in terms of hydroxymethyl furfural and diastase number. It is not known whether the decrease in the spore count was due to the death or failure in germination of the spores. At any rate, a long-term storage at 25°C or mild heating at 65°C for about 5 days may eliminate or at least to reduce C. botulinum spores in honey.
A total of 171 soil samples were collected from coasts, inlets, ponds, marshes and artificial pond in Miyazaki Prefecture to survey for Clostridium botulinum from April, 1987 to September, 1988. Botulinum toxin was detected in enrichment cultures of 18 (10.5%) out of 171 soil samples. These toxins were identified by the neutralization technique; two were type C2 and the other 16 were neutralized equally with either monovalent anti-toxin type C1 or D.
Q-TROL is an enzyme immunoassay (EIA) kit for detecting Salmonella antigens in foods by use of monoclonal antibodies against Salmonella coated on wells of plastic trays. Q-TROL was compared with the conventional method for detecting Salmonella from the same meat samples in three laboratories by the same methods. A preliminary study was performed to improve the original method described in the manual for saving time and for simplifying the procedure. As the results, it was found that the incubation in M broth at 35°C for 6 h followed by enrichemnt culture in SBG at 43°C for 18 h could be omitted, and that SBG was most effective among various selective enrichment media. One hundred chicken meat samples were analysed by both the methods, conventional and EIA, in three laboratories (A, B and C), and other 94 samples of a variety of food in laboratory C. There was a good correlation in the samples positive by both the methods without any false negative, but there were a few false positives. The EIA screening method has been regarded as a rapid and reliable method for detecting Salmonella.
SDS-polyacrylamide gel electrophoresis (SDS-PAGE) of whole-cell preparations of Campylobacter species were performed to find whether the profiles obtained by silver staining could be used for the rapid identification and differentiation among species of Campylobacter. The profiles of C. jejuni, C. coli, C. laridis and C. fetus subsp. fetus could be distinguished from one another on the basis of migration of the major bands. A major band at the position of approximately 80, 000 daltons was observed as the distinctive band of C. jejuni, and two major bands at the positions close to 80, 000 daltons were characteristic of C. coli. This method could be completed within 5 hr by use of ready-made gel and silver staining.
The main cause of Campylobacter jejuni contamination of chicken meat is thought to be leakage of feces containing C. jejuni from the vent or cross-contamination by treating with the same implements such as the chopping board, cutlery cloth and so on, during the dressing processes by the “sotomuki” (evisceration after cutting the carcass into the front and back halves) or “nakanuki” (evisceration without cutting up the carcass) method used in Japan. Improved steps which could reduce C. jejuni contamination of chicken meat are as follows: for “sotomuki”; i) closing the vent so as to avoid leakage of feces, ii) soaking the carcass in a 1-2 ppm NaClO solution for 15 min, iii) removing the internal organs on another chopping board by use of clean cloth, and for “nakanuki”, setting up or icreasing the washing steps at five points.