Salmonella Enterica Prevalence in Finishing Pigs at Slaughter Plants in Northern Italy

Identification and Characterization of Salmonella Serovars Isolated from Pig Farms in Benin City, Edo State, Nigeria: One Health Perspective

The present study was carried out to characterize Salmonella serovars from commercial pig farms in Benin City, Nigeria. A total of 81 samples were collected from the Agricultural Development Program farms between January and June 2017. Standard culture-based and polymerase chain reaction procedures were adopted in the isolation and identification of Salmonella serovars. Antibiotic susceptibility profiles of the isolates were conducted using the Kirby-Bauer disc diffusion method with prominent resistance determinants screened for using specific primer sets. The 84 identified Salmonella serovars include 15 Salmonella ser. Enteritidis, 11 Salmonella ser. Typhimurium, and 58 other Salmonella serovars. Phenotypic virulence factors include: hemolytic activity (51.7-100%), lipase activity (48.3-81.8%), protease activity (60.3-100%), gelatinase production (50-90.9%), DNA degrading activity (55.2-90.9%), and S-layer formation (63.8-100%). The biofilm formation profiles include nonbiofilm producers (0-12.1%), weak biofilm producers (0-20%), moderate biofilm producers (24.1-27.3%), and strong biofilm producers (48.3-72.7%). Salmonella serovars in this study harbored resistant determinants, such as tetA, tetC, ampC, sul1, sul2, sul3, floR, ermA, and ermC. The occurrence of resistance phenotype and determinants in pathogenic Salmonella serovars from pig farms is a significant public health concern, which could result in the dissemination of resistant elements within the environment.

Influence of Pigskin on Salmonella Contamination of Pig Carcasses and Cutting Lines in an Italian Slaughterhouse

Ninety pig carcasses and twenty one food contact surfaces (FCSs) were tested for Salmonella in a slaughterhouse processing ca. 380 pigs/h between 2014-2015. Sampling was performed during seven sessions. Four carcass sites of 100 cm2 each (back, belly, jowl externally, and the diaphragmatic area internally) were swabbed after evisceration. Meat conveyors and dressing tables were tested swabbing areas of 200 to 400 cm2. After pre-enrichment in buffered peptone water, samples were tested by Salmonella MDS® assay and the presumptive positives were confirmed by the ISO 6579 method. Salmonella isolates were serotyped following the Kauffman-White-Le Minor scheme and genotyped by XbaI pulsed field gel electrophoresis. Salmonella was isolated from 16/90 [17.8%; confidence interval (CI) 95%=11.2-26.9] carcasses and 4/21 (19.0%; CI 95%=7.7-40.0) FCSs. Four serovars were identified on carcasses. S. enterica 4,[5],12:i:-was the most prevalent (43.75%), followed by S. Rissen (31.25%), S. Derby (12.5%) and S. Bovismorbificans (12.5%). Two serovars were found on FCSs, namely S. Derby (75%) and S. Livingstone (25%). During one sampling session, a failure in carcass dehairing occurred and caused significantly higher prevalence of carcass contamination (60%) than in the remaining sessions. Moreover, in the same session, Salmonella prevalence was marginally significantly higher on FCSs than in the remaining sampling days, suggesting that dehairing affects contamination not only on carcasses, but also on the working surfaces.