Market surveillance for contamination with thermotolerant campylobacters on various categories of chicken meat in Switzerland.

From April 2009 to April 2010, 1,132 samples of different types of chicken meat were tested qualitatively and quantitatively for thermotolerant campylobacters. Samples were recovered at retail in shops from the entire territory of Switzerland and comprised imported meat and meat from domestic production. The meat categories covered by the study were refrigerated and frozen meat, meat with and without skin, and meat preparations. Overall, 38.4% of the samples were positive, and in 27.8%, Campylobacter bacteria could be quantified. Counts ranged from ≥10 to <10(4) CFU/g with a maximum value of 8 × 10(3) CFU/g in a sample of refrigerated chicken meat with skin. The contamination frequencies were 45.2% in meat with skin, 40.8% in meat without skin, and 27.4% in meat preparations. Refrigerated meat was contaminated with Campylobacter bacteria more often than frozen meat (53.9 versus 20.0%). The study also showed considerable differences between the contamination rates found for samples from different large retail chains. In 2010, a further study with 120 samples of refrigerated and sliced chicken meat and fresh chicken liver was carried out in order to test a possible seasonal variation of the occurrence of Campylobacter bacteria. The contamination frequency of sliced meat increased from 10.0% in the period from February to March to 36.7% during July to August. In both sampling periods, the counts remained in the range of ≥10 to <100 CFU/g with a maximum value of 30 CFU/g. For chicken liver, a 10.0% contamination rate was observed in the period from December to January, which rose to 100% in the period from August to October. Contrary to the results for sliced meat, not only did the frequency of contamination increase but so did the Campylobacter counts, with the highest recorded value being 2.2 × 10(4) CFU/g.