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An assessment of the proposed new International Organization for Standardization quantitative method for Campylobacter was undertaken on poultry carcass samples collected after the chilling phase of processing. Using a critical differences method, we determined the uncertainty associated with log-transformed Campylobacter numbers by dual analyses of 346 samples collected from 22 processing plants located throughout the United Kingdom. Overall, using log-transformed Campylobacter numbers that ranged between -1 and 5 log, we calculated the expanded measurement of uncertainty (EMU) to be 3.889 for the new method. The EMU changed when ranges of bacterial numbers were grouped for analyses. For low numbers of Campylobacter (<1 log), the EMU was calculated to be 5.622. There was less measurement error with higher bacterial numbers because the EMU was found to be 0.612 for samples containing Campylobacter numbers of 3 log or above. The draft method was used to measure numbers of Campylobacters on poultry carcasses collected from 18 United Kingdom processing plants in summer and winter. Numbers were significantly lower in winter. We conclude that, although the new method is adequate at quantifying high numbers of Campylobacter on poultry carcasses, further development is required to improve the measurement of small numbers of this causative agent of foodborne illness. [ABSTRACT FROM AUTHOR]

Studies to determine the appropriateness of the use of populations of indicator bacteria on poultry carcasses for process verification were undertaken in commercial slaughterhouses. Samples were collected from neck skin by excision or from whole carcass rinses and were examined for a range of presumptive process hygiene indicator bacteria. Coefficients of variation were calculated for each bacterial indicator and were significantly lower in excised samples, indicating more reproducible bacterial recovery by this sampling method. Total viable counts of aerobic bacteria, Enterobacteriaceae, and Pseudomonas in samples collected by excision had the lowest coefficients of variation when compared with other indicators and were therefore used for further study. The uncertainties associated with the quantification of each bacterial indicator were calculated and were lowest overall for total viable counts of aerobic bacteria. In general, uncertainty was higher for lower bacterial numbers. Results of microbiological testing on pooled excised neck skin samples were not significantly different from the mean of individually analyzed samples. Bacterial numbers increased by 1 log unit when cultures were stored under chilled conditions typical of those used for transporting samples to external laboratories, but the increases were not significant for Pseudomonas and aerobic bacteria when storage time was less than 17 h. Weak relationships were identified between bacterial indicator numbers and duration of processing, although cleanliness of the processing environment diminished visibly during this time. In the plants visited for this study, there was a poor relationship between presumptive bacterial indicator numbers and process hygiene. Consequently, bacterial analyses for process verification purposes may be of limited value. [ABSTRACT FROM AUTHOR]

s.m. avery, l.d. walters and m.l. hutchison. 2004.The fate of inoculatedEscherichia coliO157,stxphages and the physico-chemical properties of maize were studied during laboratory-scale fermentation by naturally occurring lactic acid bacteria.Before fermentation, chopped maize was inoculated with 6·2 log10 CFU g−1 of a five-isolate mixture ofE. coliO157. After fermentation, the silage contained 70·6 g kg−1 dry matter (DM) lactic acid and 12·8 g kg−1 DM acetic acid and was pH 4·0. Levels ofE. coliO157 fell rapidly, and none of the five isolates could be recovered from the fermenting maize after 8 days. Using a resuscitation step did not consistently enhance recovery ofE. coliO157.Stxphages were not isolated from the fermenting maize at any time. Pulsed-field gel electrophoresis (PFGE) genotyping showed thatE. coliO157 2975 and 64a/01 survived better than the other three isolates studied.Escherichia coliO157 isolate 1474/00 was particularly sensitive to the laboratory procedures used to harvest the inocula and contaminate the maize. Some colonies recovered during the fermentation had one to three band alterations compared with the initial PFGE genotypes.None of the five differentE. coliO157 genotypes survived maize fermentation. Fermentation of maize produces an animal feedstuff that is unlikely to containE. coliO157 orstxphages. [ABSTRACT FROM AUTHOR]