Correlation of salmonella spp. In pigs at slaugther as determined by bacterial culture and salmonella ELISA

Abstract

<p>The purpose of this study was to detennine the prevalence of Salmonella spp. in pigs at slaughter by bacterial culture, and serology using the Danish Mix-ELISA. Fecal samples and mesenteric lymph nodes were collected from 20 farms (30-35 samples per farm) and cultured for Salmonella on XLD agar following a pre-enrichment in buffered peptone water at 37° C for 24 hours and enrichment in Rappaport-Vassiliadis broth at 42° C for 24 hours. Eighteen of 20 farms yielded at least one positive sample by culture with farm sample prevalence ranging from 3.3% to 96.6%. There were 16 different serotypes of Salmonella isolated. Individual farms had from 0 - 6 different serotypes detected by bacteriologic examination. The Danish Mix-ELISA, developed by Nielsen et al. and currently used in the Danish slaughter plants, was used to test sera collected at slaughter. Using the Mix-ELISA, 16/20 farms were positive with farm sample prevalence ranging from 28.6% to 100%. In comparing the farms, there was a direct correlation between lymph node culture and MixELISA detection levels. These data suggest that the Mix-ELISA may be a valuable herd screening tool for the evaluation of Salmonella levels in U.S. swine herds. Also, these data suggest that vaccination of pigs with SC-54 significantly reduces the prevalence of Salmonella when measured by serology, mesenteric lymph node culture, and fecal culture.</p>