Behavior of Vibrio cholerae in hot foods

Four food types held hot at 45 to 60 degrees C were deliberately contaminated with O1 and non-O1 Vibrio cholerae strains. These organisms were assayed for survival and recovery from the foods within 1 h of the time the food was kept hot. The results showed no growth of V. cholerae non-O1 on thiosulfate-citrate bile-sucrose agar plates after 24 h of incubation at 37 degrees C for food held hot at 50 to 60 degrees C. Growth was low for V. cholerae O1 and was not achieved in some instances in which foods were held at either 55 or 60 degrees C after 40 or 60 min of from the time the food was kept hot. Both organisms, however, were recovered equally from all food types held at all temperatures after 48 h of incubation. When incubated for an additional 24 h, the organisms grew to unusually small-sized colonies, measuring 0.1 to 0.3 mm in diameter, on the same agar plates that were negative for growth after an initial 24 h of incubation. It was concluded that V. cholerae survived the period of time held at hot temperatures. Although the organisms were not recovered from some foods when held at some of the temperatures and times after 24 h of incubation, they remained viable. An incubation period of 48 h at 37 degrees C was found to be appropriate for the recovery of V. cholerae from hot foods.