Differences in survival of Escherichia coli O157:H7 under various conditions that re-enact the cooking of lunches implicated in an outbreak of haemorrhagic diarrhoea.
Two elementary schools were served lunches that were cooked in the same kitchen. An outbreak of Escherichia coli O157:H7 occurred at one school where the dishes that were prepared for the school were lukewarm and kept for 33 min at an average temperature of 45 degrees C before serving. However, no outbreak occurred at the other school where dishes were hot and were kept for 60 min at an average temperature of 50 degrees C before serving. In a series of experiments on the survival of E. coli O157:H7 in the liquid portion of similarly prepared food, the population of E. coli O157:H7 was reduced by 10-3 by heating at 50 degrees C for 60 min and by only 10-1 by heating at 45 degrees C for 40 min. Further, E. coli O157:H7 survived at 45 degrees C for 40 min but not at 50 degrees C for 60 min at pH 4.0 with a 4.0% salt concentration that was similar to that of the liquid part of the food. These results indicate that pH and salt concentration of cooked food markedly affect the survival of E. coli O157:H7 and help to explain the occurrence of the disease outbreak at only one of the schools.
Hara-Kudo
Y
Y
Division of Microbiology, National Institute of Health Sciences, Tokyo 158-8501, Japan. ykudo@nihs.go.jp
Watanabe
H
H
Konuma
H
H
D003967:Diarrhea / Q000453:epidemiology*; D004196:Disease Outbreaks / Q000706:statistics & numerical data*; D019453:Escherichia coli O157 / Q000187:drug effects / Q000254:growth & development*; D005506:Food Contamination / Q000032:analysis / Q000517:prevention & control; D005511:Food Handling / Q000379:methods* / Q000706:statistics & numerical data; D005516:Food Microbiology; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008461:Meat Products / Q000382:microbiology; D012965:Sodium Chloride / Q000494:pharmacology*; D013696:Temperature; D013997:Time Factors
D012965:Sodium Chloride