Heat resistance of Campylobacter and Yersinia strains by three methods

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Abstract
Two methods of determining the heat resistance of bacteria, a glass cup and a test tube method, were compared with a method using capillary tubes. Three strains of Yersinia enterocolitica, one of Campylobacter jejuni and two of C. coli were tested in physiological saline. The differences between the results obtained by the glass cup method and the reference method were not statistically significant for five strains and were small also for the other, a Yersinia strain. D values obtained by the glass cup method at 58, 60 and 62.degree.C were 1.4-1.8; 0.40-0.51 and 0.15-0.19 min (z values 4.00-4.52.degree.C) for the Yersinia strains, and 0.42, 0.13 and 0.07 min (z value 5.07.degree.C) for one C. coli strain. For the other Campylobacter strains, D values of 0.71-0.78, 0.24-0.28 and 0.12-0.14 min (z values 4.94-5.60.degree.C) were recorded at 56, 58 and 60.degree.C. D values obtained at 60.degree.C by the test tube method were 2.7-5.0 min and were considered to be unrealistic.