Heat resistance in liquids of Enterococcus spp., Listeria spp., Escherichia coli, Yersinia enterocolitica, Salmonella spp. and Campylobacter spp

The aim of the work was to collect, evaluate, summarize and compare heat resistance data reported for Campylobacter, Enterococcus, Escherichia, Listeria, Salmonella and Yersinia spp. The work was limited to resistance in liquids with pH values 6-8. Results obtained under similar experimental conditions were sought. Thermal destruction lines for the various bacterial groups studied were constructed using log10 D values and treatment temperatures. There was a good linear relationship between log10 D and temperature with Escherichia coli, listerias and salmonellas. For campylobacters, enterococci and yersinias the relationships were weaker but, nevertheless, present. Using the slopes of the lines and their 95% confidence limits, z values and their 95% confidence limits were calculated. z values were compared with z values obtained from reports. The equations for the lines were also used for calculation of predicted means of D values at various treatment temperatures. 95% confidence limits on predicted means of D values and on predicted individual D values were also calculated. Lines and values are shown in figures and tables. Differences in heat resistance noted between and within the bacterial groups studied are discussed.

Characterization of Campylobacter jejuni/coli isolated from different sources

Characteristics of 50 strains of G. jejuni/coli isolated from rectal swabs, caecal contents or bile of cow, sheep, goat, swine, broiler chicken and man were investigated. All the strains grew at 30 °C, 35°C 42°C, but not at 25 °C. The strains were nalidixic acid sensitive. Differences were noticed in salt-tolerance, in the growth with 2,3,5 tri-phenyltetracolium chloride and in the hippurate hydrolysis. Growth of the strains with certain bile salts was also investigated and the results are discussed.