Prevalence of Listeria monocytogenes in broilers at the abattoir, processing plant, and retail level

The environment and products from two broiler abattoirs and processing plan ts and raw broiler pieces at the retail level were sampled for Listeria mon ocytogenes in order to evaluate the contamination level of the broiler carc asses and products. Sampling started in the slaughtering process and finish ed with raw broiler meat or ready-to-eat cooked product. Sampling sites pos itive for L. monocytogenes at the broiler abattoir were the air chiller, th e skin-removing machine, and the conveyor belt leading to the packaging are a. The L. monocytogenes contamination rate varied from 1 to 19% between the two plants studied. Furthermore, 62% (38 of 61) of the raw broiler pieces, bought from retail stores, were positive for L. monocytogenes. Altogether, 136 L. monocytogenes isolates were obtained for serotyping and pulsed-fiel d gel electrophoresis (PFGE) characterization performed with two rare-cutti ng enzymes (ApaI and AscI). Altogether three serotypes (1/2a, 1/2c, and 4b) and 14 different PFGE types were obtained using information provided from both ApaI and Asci patterns for discrimination basis. The two broiler abatt oirs studied did not share the same PFGE types. However, the same PFGE type s found in the raw broiler pieces at the retail level were also found in th e broiler abattoirs where the broilers had been slaughtered.