The magnetic beads (MB) method was compared with a conventional culture method for the detection of Salmonella. In 126 samples of commercial chicken meat, Salmonella was isolated from 36 samples by the conventional culture method and MB agglutination method, respectively. Salmonella was isolated from 93 samples by the MB culture method. In 78 samples of chicken feces, Salmonella was isolated from 2 samples and 9 samples by the conventional culture method and the MB culture method, respectively. By the MB agglutination method, Salmonella can be detected in just 2 days, while it takes 4 days for the MB culture method to identify Salmonella. This MB method was found to be useful for rapid detection of Salmonella.
An outbreak of gastroenteritis due to enterohaemorrhagic E. coli O157:H7 involving 185 patients (51%) among 364 persons occurred at a primary school in Hiroshima prefecture between June 1-17, 1996. Ninety-five patients were admitted to hospital, but there were deaths. The main symptoms were abdominal pain (77.7%), diarrhea (48.6%) and headache (7.4%). In most patients, the stools were watery and contained mucocus, but hemorragic stools were rare (5/68). On bacteriological study of stool specimens, E. coli O157:H7 was isolated from 47 patients at concentrations of 10-108 CFU/g. The amount of VT in feces was 2-128ng/g by RPLA, and correlated with the CFU of O157:H7 in patient stool. Antibody titers against O157 LPS were between ×64 to ×2,048 (33/37) in the patient sera. The isolates of E. coli serovar were positive for production Shiga-like toxin 1,2 and eaeA gene by PCR. All strains showed the same plasmid profiles with 94kb, 80kb and 3.5kb plasmid DNA, and the same RAPD profiles and restriction fragment pattern by PFGE of chromosomal DNA.
Bacterial flora of Kaburazushi (fermented turnip and yellowtail with malted rice), which is a traditional fermented food in Kanazawa, Japan, was surveyed by a simple method. Samples were obtained from four different factories. Lactobacillus, Streptococcaceae, cocci-other and coliforms were detected in samples. Predominant bacterial groups in Kaburazushi were Lactobacillus, however samples obtained from different factories and/or on different day showed different numbers of Lactobacillus and pH values. In the case of samples having large numbers of Lactobacillus, the pH value was lower. During storage at 4°C, the numbers of Bacillus and pH value did not change. Lactobacillus decreased with days of storage. Streptococcaceae were dominant after storage for 14 days, however Streptococcaceae were not detected after storage for 27 days.
We conducted epidemiological and bacteriological studies of five episodes of food poisoning caused by diarrheagenic Escherichia coli (E. coli) at cookeries in Oita Prefecture, in which the disease-causing bacteria were isolated. There were two cases of enteropathogenic E. coli (EPEC), in which O86a:H27 and O44:H18 were isolated, and three cases of enterotoxigenic E. coli (ETEC), in which heat-stable enterotoxin (ST)-producing O27:H7, ST-producing O153:H10 and heat-labile enterotoxin (LT)-producing O25:HNM (not mobile) were isolated. When food poisoning arose from school lunches, there were 406 patients, and O44:H18 (EPEC) was isolated from patients' stools and from ramen (cold Chinese noodles in soup). From the result of gene analysis using plasmid profiles and random amplified polymorphic DNA (RAPD) profiles, both pathogens proved to be the same origin. In this case, cell adhesion test and a search for the EPEC adherence factor (EAF) and eae gene were performed without results. The results of epidemiological studies showed that, compared with EPEC, many patients with food poisoning caused by ETEC tended to have diarrhea more than ten times a day, vomiting and fever more than 38°C. ETEC food poisoning has a longer incubation period.