Effect of storage temperatures on growth and survival of Escherichia coli O157: H7 inoculated in foods from a neotropical environment.

ABSTRACT

Escherichia coli O157 H7 has emerged as a new pathogen and is found worldwide. We studied the effect of several storage temperatures on the survival of this bacterium in common foods from a neotropical environment (Costa Rica) because at least seven clinical cases have been reported from the country, and no epidemiological link or probable food association has been described. High (10(6)-10(8) CFU/ml) and low (10(4)-10(6) CFU/ml) populations of E. coli were inoculated (three replications) in ground meat, chopped cabbage, chicken giblets and pasteurized milk and incubated at 0, 6 and 12 degrees C for 24, 48 and 72 h. Vegetables and milk were also stored at 22 degrees C for the same periods. The E. coli O157 H7 enumeration was done according to the methodology described in the Bacteriological Analytical Manual. Populations of E. coli O157 H7 showed either an increasing or decreasing trend, according to temperature, time or food base. Our data indicate that E. coli O157 H7 is capable of surviving and growing in meat, cabbage, milk and chicken giblets; food items commonly consumed by Costa Ricans.