Salmonella on pig carcasses: positive pigs and cross contamination in the slaughterhouse

Abstract

Aims: The purpose of this study was to investigate the prevalence of Salmonella in pigs at the moment of slaughter and in the slaughterhouse environment. Methods and Results: In total, five different commercial slaughterhouses were sampled during eight slaughterhouse visits. Carcass swabs, colon content and mesenteric lymph nodes were taken to reflect the animal status and from the slaughterhouse environmental samples were taken.Salmonella was isolated from 37% of the carcass samples as a mean value. High variations were noticed between different slaughterhouses (between 0 and 70%) and sampling days in the same abattoir (between 3 and 52%). A correlation was found between the carcass contamination and the status of the delivered animals (P ¼ 0AE01675). Cross contamination was estimated to account for 29% of the positive carcasses. The slaughterhouse environment was highly contaminated; before starting the slaughtering activities 25% of the samples were positive on average. The most prevalent serotypes isolated at the slaughterhouse environment and from the colon content were S. Typhimurium, S. Livingstone and S. Derby. On carcasses S. Typhimurium was predominately isolated (71%). The biggest variability of serotypes was found in the mesenteric lymph nodes.Serologically 56AE3% of the pigs were found positive for Salmonella using a cut-off level of the optical density percentage higher than 10 (O.D.% ‡ 10). While on individual pig level the correlation between the bacteriological and serological data was poor, because of recent Salmonella infections, a better correlation was found at the herd level on the moment of slaughtering. Conclusion: A high degree of carcass contamination is noticed after slaughtering. This contamination resulted from the delivery of Salmonella-positive pigs and cross-contamination from the slaughterhouse environment. Significance and Impact of the Study: In pigs, Salmonella carriage is high, but it is obvious that slaughterhouse hygiene is a determinative factor for managing carcass contamination.

Discrepancies between the isolation of Salmonella from mesenteric lymph nodes and the results of serological screening in slaughter pigs

“…However, when logistic slaughtering is applied, it is the presence of Salmonella spp. in a shipment that is important regarding contamination of carcasses [5,7,29]. The aim of the present study was therefore to investigate the possible discrepancies between the isolation results of Salmonella and the results of serological screening methods.…”

Genetic diversity of Shiga toxin-producing Escherichia coli O157 : H7 recovered from human and food sources

“…SBI genotypes of strains were determined as published (Besser et al, 2008;Shaikh & Tarr, 2003) with minor modification. Amplification of yehV or wrbA was performed in two multiplex PCRs for detection of bacteriophage integration and amplification of stx 1 and stx 2 genes was performed in two uniplex reactions as described (Botteldoorn et al, 2003). Multiplex no.…”

“…Detection of stx 1 and stx 2 genes was performed by PCR using primer sequences and cycling conditions previously described (Botteldoorn et al, 2003) (Table S1). Isolates that showed a positive result for stx 2 were further tested for the presence of stx 2a and stx 2c by their respective PCR (Wang et al, 2002).…”

Salmonella in sows: a longitudinal study in farrow-to-finish pig herds

“…In order to prevent human disease due to the consumption of Salmonella contaminated pork, many studies have focussed on the epidemiology and the control of Salmonella in finishing pigs [5,18,23,34,35]. Also many studies have focussed on the lairage and the slaughterhouse in order to prevent contamination of pig carcasses as much as possible [4,7,8,31]. One of the general conclusions of these studies is that the Salmonella problem has to be tackled during the different steps of the production cycle, starting at the herd level.…”