External contamination of broilers byspp. increases from the farm to the slaughterhouse.

Abstract

1. In this study, classical and molecular microbiological methods for detection and quantification ofspp. were used to estimate their prevalence in faecal samples and skin swabs collected from 31 broiler flocks (20 farms) in Portugal, and measure the impact of transport-related factors on the expected rising excretion rates from the farm to the slaughterhouse. 2. Data on husbandry practices and transport conditions were gathered, including time in transit, distance travelled orplant-holding time. 3. A generalised linear mixed model was used to evaluate the significance of a potential post-transport rise inspp. counts and to assess risk determinants. 4. At least one flock tested positive forspp. in 80% of the sampled farms. At the slaughterhouse,spp. were detected in all faecal samples,being the most commonly isolated. 5. A post-transport rise ofspp. counts from skin swabs was observed using classical microbiological methods (from a mean of 1.43 to 2.40 logCFU/cm) and molecular techniques (from a mean of 2.64 to 3.31 loggenome copies/cm). 6. None of the husbandry practices or transport-related factors were found to be associated withspp. counts. 7. This study highlights the need for more research to better understand the multi-factorial nature ofspp., a public health threat that was found to be highly prevalent in a sample of Portuguese poultry farms.