Effect of temperature on viability of Campylobacter jejuni and Campylobacter coli on raw chicken or pork skin

To determine growth and survival of Campylobacter jejuni and Campylobacter coli on chicken and pork, Campylobacter Spp. (10(4) CFU/cm(2)) were inoculated on pieces of raw, irradiated chicken or pork skin and exposed to temperatures ranging from -20 to 42degreesC under either microaerobic or aerobic conditions. Viable counts over 48 h declined 2 to 3 log CFU/cm2 at -20degreesC and 1 to 2 log CFU/cm(2) at 25degreesC regardless of skin type, species of Campylobacter, or level of oxygen. At 4degreesC, there was no significant change in the number of Campylobacter over 48 It. At both 37 and 42degreesC, the number of viable Campylobacter increased significantly (2 to 3 log CFU/cm(2), p < 0.0001) under microaerobic conditions but decreased 0.5 to 1.5 log CFU/cm(2) in air. Preincubation of skins for 24 h at 42degreesC under microacrobic conditions to establish Campylobacter on the surface prior to lowering the temperature to -20, 4, or 25degreesC and incubating in air resulted in a decline in viability for the first 4 h (0.5 to 1 log CFU/cm(2)). However, after this initial drop in viability, no additional effect on viability was observed compared with incubation at -20, 4, or 25degreesC in air without microaerobic preincubation at 42degreesC. Preincubation of inoculated skins at -20, 4, or 25degreesC in air for 24 h followed by a shift in temperature to 42degreesC for 4, 8, 24, or 48 It and a shift to microaerobic conditions resulted in an overall decline in viability on raw pork skin but not on raw chicken skin. In contrast, preincubation of inoculated skins at -20, 4, or 25'C for 24 h in air followed by a shift in temperature to 37degreesC and microacrobic conditions did not result in a decrease in viable counts for either chicken or pork skins. Overall, viability of C. coli and C. jejuni on chicken and pork skins was similar. Therefore, a lower incidence of Campylobacter spp. in pork than in poultry postslaughter, despite a similar prevalence in live animals, is not due to differences in viability of C. coli versus C. jejuni on raw chicken or pork skin.