Drinking Pipes and Nipple Drinkers in Pig Abattoir Lairage Pens - A Source of Zoonotic Pathogens as a Hazard to Meat Safety

Abstract

The water distribution system in the lairage pens of abattoirs could act as a route of contamination for produced meat. In this study, biofilm formation and the occurrence of specific pathogens in drinking equipment was investigated in different lairage pens in a German commercial pig abattoir. Samples of the water and the drinkers in different locations were microbiologically cultivated and examined. After new drinking equipment had been installed for one month, three months and five years, biofilm formation was detectable, and retrograde growth from the nipple drinkers was seen up to the connection with the main water distribution system. In particular, <i>Enterobacteriaceae</i> and <i>Pseudomonas</i> spp. were found in all samplings of the nipple drinkers. Zoonotic pathogens, <i>Salmonella</i>, pathogenic <i>Yersinia enterocolitica</i> and methicillin-resistant <i>Staphylococcus aureus</i>, were also isolated from the nipple drinkers, while <i>Listeria monocytogenes</i> was not detected via microbial cultivation methods in any of the samples. Since the pigs take the contaminated nipple drinkers into their mouths to drink, or drink contaminated water containing the pathogens, transmission and even infection of the pigs in the lairage can be assumed. This could consequently lead to contamination or cross-contamination of the meat during slaughter and processing and to a public health risk.