Occurrence of Salmonella, Campylobacter, Yersinia enterocolitica, Escherichia coli O157 and Listeria monocytogenes in Swine

Abstract

The objective of this study was to investigate the occurrence of major bacterial foodborne pathogens in swine. In total, 359 samples from manure storage tanks (91) and fresh pooled faeces (268) obtained from finisher (110), sows (78) and weanlings (80) were collected and tested. Campylobacter, Salmonella, Yersinia enterocolitica, Escherichia coli O157 and Listeria monocytogenes were isolated from 36.5%, 31.5%, 5.8%, 3.3% and 3.3% of samples respectively. All E. coli O157 isolates found on 10 farms were tested but none was determined to be E. coli O157:H7. Salmonella and Campylobacter were more likely to be detected from stored manure rather than from fresh faecal samples. Yersinia enterocolitica tended to be detected more commonly from fresh samples than from manure pits. Listeria monocytogenes was not recovered from manure pits or from sow faecal samples and only infrequently found in the faeces of weanling pigs and finisher pigs. The proportion of positive samples showed a seasonal change. Salmonella was twice as likely not be recovered in winter, whereas the chance of culturing Campylobacter was higher in winter. The 113 Salmonella isolates recovered on 24 farms and the four most common serovars were Salmonella Typhimurium var. Copenhagen (31.0%), Salmonella Derby (12.4%), S. Typhimurium (10.6%) and Salmonella Agona (10.6%). Of 131 Campylobacter isolates recovered on 21 farms, 118 isolates were Campylobacter coli and 13 isolates could not be speciated. Fifteen of 21 Y. enterocolitica isolates found on 15 farms were detected in finisher pigs. The sero/biogroups of Y. enterocolitica were O3/biotype 4 (16 isolates), O6,30/biotype 1A (three isolates), O5/biotype 1A (one isolate) and O8/biotype 1B (one isolate). These findings provide baseline information on the distribution of important zoonotic pathogens in swine and indicate that pigs should be considered as a possible source of foodborne diseases in humans.

Analysis of Listeria monocytogenes Strain Distribution in a Pork Slaughter and Cutting Plant in the Province of Quebec

“…Low contamination rates of the pigs at the farm could explain the low contamination levels found in this area of the slaughterhouse. This is supported by other studies, which report fecal contamination levels ranging from 0 to 16% at slaughterhouses (16,17,19,28,50). Furthermore, the pathogen was found only in three of nine visits.…”

“…This serovar was also linked to a cheese-associated outbreak that occurred in the same year animals (5,30,53). L. monocytogenes has been found in the feces, intestines, and tonsils of healthy pigs on farms at levels ranging from 0 to 61% (16,30,47,53). Contaminated pigs could therefore be responsible for the contamination of the environment in lairage pens or during the slaughtering and processing operations (4,25).…”

Prevalence and Distribution of Listeria monocytogenes Serotypes and Pulsotypes in Sows and Fattening Pigs in Farrow-to-Finish Farms (France, 2008)

“…Few works have described the excretion of L. monocytogenes by sows. A recent Canadian study (10) explored the contamination of L. monocytogenes at different production stages (finisher, sows, and weanlings). This study indicated that L. monocytogenes was not recovered from sow fecal samples and only infrequently found in the feces of weanling pigs and finisher pigs.…”

Escherichia coliO157:H7: Animal Reservoir and Sources of Human Infection

“…However, EHEC O157:H7 can be highly pathogenic in swine and are rarely found in these animals; a 2-year multifarm survey in the United States did not yield any isolates (Richards et al, 2006) and in another 13-state survey no H7 or hly933 were detected among 106 isolates of EC O157 from healthy pigs (Feder et al, 2007); in Canada EC O157 were found in 3% of samples from 10 farms, but no EC O157:H7 (Farzan et al, 2009). In the United Kingdom, an abattoir survey yielded EHEC O157 from 15.7% of cattle and 2.2% of sheep, but only from 0.4% of pigs; while almost all of 752 cattle isolates and all 22 sheep isolates were stxþ with a 92 Kb plasmid, these virulence factors were absent in swine isolates , that are typically deficient in major virulence factors.…”