Hiromi Ogawa

Enterotoxigenicity of Staphylococcus intermedius strains isolated from dogs

Dogs (n = 100) were examined for the presence of enterotoxigenic Staphylococcus intermedius. Enterotoxigenic strains were isolated from the nasal cavities of 43 (43.0%) out of 100 dogs. Of the 50 enterotoxigenic strains isolated, 23 (46.0%) produced enterotoxin A, 17 (34.0%) enterotoxins A and C, 8 (16.0%) enterotoxin C, and only two (4.0%) enterotoxins A and B. The amount of enterotoxin produced on semisolid brain heart infusion medium by the 17 enterotoxin A producing strains of S. intermedius was 10-160 ng per ml. Enterotoxin A production by S. intermedius strains was ony one tenth to one hundredth of that of S. aureus strains from staphylococcal food poisoning outbreaks.

Calendar Effects (Month and Day-of-the-week) in the Scale of Food Poisoning Outbreaks in Hiroshima Prefecture

We studied calendar effects (month and day-of-the-week) on the scale of food poisoning outbreaks (classified into 3 groups by the number of patients per outbreak) using statistical methods. Data on food poisoning outbreaks in hotels, restaurants and catering establishments during May to October between 1965 and 1991 in Hiroshima prefecture were used.The Kruskal-Wallis test revealed no significant differences among the numbers of patients by month and day-of-the-week. Applying a log-linear model, however, we did find calendar effects on the scale of outbreaks. The small-scale outbreaks (≤7 patients) tended to occur in the months of May and June, and on Fridays. The outbreaks of moderate scale (8-44 patients) tended to occur in July, August and September. The large-scale outbreaks (≥45 patients) tended to occur in May, June and October, and on Mondays and Tuesdays.