Tracking the Salmonella Status of Pigs and Pork from Lairage through the Slaughter Process in the Republic of Ireland

Abstract

Salmonella Typhimurium is the predominant serotype isolated from humans in Europe. Pork and pork products are recognized vehicles of Salmonella and are responsible for outbreaks of human salmonellosis. Pigs can become infected with Salmonella on the breeding or fattening farm and during transport, lairage, and slaughter. The aim of this study was to investigate selected points of Salmonella contamination from the time pigs entered the lairage to the time the carcass was processed in the boning hall and to determine the importance of different sources of Salmonella along the Irish pork production chain. A second objective was to evaluate whether the serological status or category of a herd influenced the levels of bacteriological contamination detected on individual carcasses and pork cuts during slaughter and dressing operations. All samples were tested for the presence and numbers of Salmonella. Enterobacteriaceae numbers were also determined. Serotype, phage type, and pulsed-field gel electrophoresis were utilized to determine similarity among Salmonella isolates. Lairage was a major source of cross-contamination with Salmonella as were the hands of evisceration operatives, conveyor belts, and equipment in the boning hall. Cross-contamination within the slaughter plant environment accounted for up to 69 % of Salmonella carcass contamination. In general, herd category reflected the bacteriological status of carcasses and pork cuts. Major findings were a strong association (P < 0.01) between Enterobacteriaceae counts and Salmonella occurrence on prechill carcasses and a significant association (P < 0.05) between Enterobacteriaceae counts and Salmonella occurrence on pork cut samples.

Evidence of Metabolic Switching and Implications for Food Safety from the Phenome(s) of Salmonella enterica Serovar Typhimurium DT104 Cultured at Selected Points across the Pork Production Food Chain

“…2B). These findings are consistent with the view that most contamination of meat and meat products originates during the processing phase of the food chain and the fact that there is limited transfer from environmental sources (5,7,8).…”

“…These strains were cultured as part of an extensive surveillance study of the Irish pork food chain (7,10,11). The collection included bacteria cultured from the farm environment (11), the abattoir environment (7), retail pork products (10), and from clinical specimens (gently given by Martin Cormican, from the National Salmonella Reference Laboratory, NUI Galway, Ireland).…”

“…A previous study, conducted in the Republic of Ireland, investigated selected points of Salmonella contamination from the time pigs entered the lairage to the time the carcass was processed in the boning hall, to determine the importance of different sources of Salmonella along the Irish pork production chain (7). Lairage was found to be the major source of cross-contamination with Salmonella, followed by the hands of evisceration operatives, conveyor belts, and equipment in the boning hall.…”

Prevalence, Enumeration, Serotypes, and Antimicrobial Resistance Phenotypes of Salmonella enterica Isolates from Carcasses at Two Large United States Pork Processing Plants

“…Known Salmonella contamination sources prior to entering the processing plant include swine production farms, transport trailers, and lairage pens (25,26,35,42,43,55). Transportation and lairage are likely sources of contamination, since exposure of uninfected swine to contaminated transport trailers or lairage pens results in rapid infection of lymph nodes, cecal contents, and rectal contents (26,28,45,46,55,57,59). Other potential sources of prescald carcass contamination include belts or elevators colonized by Salmonella.…”

Salmonella Control Measures at Farm in Swine Production

“…As it has been proposed by Davies et al (2004) the food supply should be seen as a linear series of sectors engaged in production, harvest, distribution and consumption and the goal of control programmes is to define the optimal combination of interventions at each sector that delivers the maximum risk reduction at minimal cost. It has been demonstrated that the risk of Salmonella contamination increases across the pork production chain and reaches its maximum in the slaughterhouse (Duggan et al, 2010;Argüello et al, 2011a;Visscher et al, 2011). Therefore, the slaughter process seems to be the main target to implement control measures and its importance has been pointed by many studies (Hurd et al, 2002, Argüello et al, 2011a.…”