Two types of food poisoning from Bacillus cereus, the emetic type caused by emetic toxins and the diarrhea type caused by enterotoxins, have been reported . Most cases in Japan are the emetic type, therefore, the cereulide needs to be proven when B. cereusfood poisoning is suggested. The original detection method for cereulide is performed by microscopic assessment of vacuole formation in HEp-2 cells, but it involves some judgement problems that require adept skills as well as reproducibility of the result. Furthermore, it also requires considerable labor to obtain and maintain the cells. Recently, an analysis method using liquid chromatography-mass spectrometry (LC-MS), which shows excellent accuracy, quantification, specificity and reproducibility is often used to detect cereulide. In this paper, we compared Nutrient broth containing manganese and glucose (NB+Mn) medium as previously recommended and 10% skim milk medium for the production of cereulide, and further investingated the influence of heat-treatment process of culture fluid on the recovery of cereulide measured by LC-MS.
An outbreak of food poisoning occurred in nursing welfare facilities for elderly people in the Miyagi prefecture on August 2005. Salmonella entericasubsp. enterica serovar Montevideo (S. Montevideo) was isolated from the stool of patients, leftover salad and white radish sprouts. It was determined that the white radish sprouts produced by a certain sprouts grower were the causative food. The amount of bacterium intake per personwas assumed to be about 10, 000 MPN or less, because of the 960 MPN/g of isolates from white radish sprouts. Simultaneously outbreak strains of S. Montevideo were isolated from commercial white radish sprouts produced by the sprout grower and from the stools of other sporadic salmonellosis patients in the prefecture. As a result of PFGE analysis, these isolated strains were thought to be of the same origin. This shows that the white radish sprout may have been associated with both food poisoning outbreak and sporadic infections.
Comparative gyrB gene sequence analyses performed on type/reference strains of Alicyclobacillus species and three A. acidoterrestrisstrains demonstrated that gyrBgene was very diverse among species. However, the gyrB gene sequences of A. acidoterrestris was highly conserved within species at more than 97.6% sequence similarity . Based on these results, re-gions characteristic of A. acidoterrestriswere found and primers including that region were designed in order to specifically detect A. acidoterrestris (three forward primers and two reverse primers). Using all possible combinations of the primers, PCR reactions were carried out with A. acidoterrestris-derived DNAs. The results showed that the predicted length fragments were accurately amplified in every primer set. Apart from certain exceptions there were used in the LAMP method, it was confirmed that this amplification reaction occurred only with A. acidoterrestris. These findings indicate that A. acidoterrestris can be accurately and rapidly detected using these specific primers designed here in the PCR-electrophoresis method and/or the LAMP method.
Both the incidence and number of patients with food-borne diseases caused by Salmonellastill rank very high among total food-borne diseases, although both have been decreasing in recent years. The need for a simple and rapid alternative method of Salmonellatesting is very high in the food industry because the conventional culture method includes two enrichment procedures and takes more than five days to isolate and identify a typical colony of Salmonella from samples. VIDAS is an enzyme-linked fluorescent assay (ELFA) system that consists of a fully automated device and its reagents. In this study, we compared two protocols of the VIDAS method with the conventional culture method for detecting Salmonella using 40 food samples. Performances of protocols “ VIDAS ICS + plate ”and “ VIDAS SLM AFNOR validated method” both showed higher sensitivity than the conventional culture method. These protocols were also excellent in terms of reduced time-toresults in addition to showing higher sensitivity. We also compared SMID 2, a new chromogenic agar plate for selective isolation of Salmonella, with DHL agar, a traditional agar plate for Salmonella testing. On SMID 2, typical colonies of Salmonella were much easier to identify (mainly by its characteristic color), and the frequency of appearance of typical colonies by bacteria other than Salmonella was much lower, although the Salmonella recovery rate did not differ between the two media.