Experimental production of staphylococcal enterotoxins A, B, and C on rice flour gel medium

Production of staphylococcal enterotoxins A, B, and C was studied on the rice flour gel plate consisting of rice flour and distilled water devised by the authors simulating cooked rice that has commonly been incriminated for staphylococcal food poisoning in Japan. Enterotoxin produced on the rice flour gel plate was determined quantitatively by reversed passive hemagglutination. The rice flour plate supported production of fairly large quantities of enterotoxins A, B, and C. The rice flour concentration of the plate and the quantity of the surface water largely affected the enterotoxin production. The largest amount of enterotoxin, 0.2-0.4 mg/25-ml plate, was produced in 3 days at 37 C on 16% rice flour gel plates overlaid with 4 to 8 ml of saline. It appeared that the production of enterotoxin A was more rapid than that of enterotoxin B or C.