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United States Department of Agriculture

Agricultural Research Service

Title: Comparison of Initial Enrichment on the Recovery of Salmonellae from Swine Lymph Nodes and Cecal Contents at Slaughter

Authors
item Harvey, Roger
item Anderson, Robin
item Farrington, Leigh - TEXAS A&M UNIVERSITY
item Droleskey, Robert
item Genovese, Kenneth - TEXAS A&M UNIVERSITY
item Stanker, Larry
item Nisbet, David

Submitted to: International Symposium on Epidemiology and Control of Salmonella in Pork
Publication Type: Proceedings
Publication Acceptance Date: June 1, 1999
Publication Date: N/A

Technical Abstract: We conducted an epidemiological survey to determine the prevalence of salmonellae in an integrated swine operation. The survey design called for 4 representative farms (farrow to finish) to be sampled 3 times each, and a fifth farm once. Samples were collected at slaughter from 50 pigs per sampling period per farm and consisted of ileocolic lymph node and cecal contents. Culture techniques were as follows: equal amounts of samples (cecal and lymph node) were pre-enriched for 24 h with both tetrathionate and GN Hajna broth, were enriched with Rappaport Vassiliadis (RV) broth for 24 h, and were streaked onto brilliant green agar containing novobiocin and incubated for 24 h. Suspect colonies were inoculated into lysine iron and triple sugar iron agar, H2S-positive cultures were confirmed by polyvalent-A Salmonella latex agglutination, and pure cultures were serotyped by the National Veterinary Services Laboratory. We isolated salmonellae from 61% of pigs sampled. We found 33 serovars in 415 serotyped samples, but 85% of the isolates were represented by 10 serovars. Fifty-one pigs had multiple serovars isolated. When comparing the frequency of isolations from sample sources, 60% were from lymph nodes and 40% were from cecal contents. There was no difference (P>0.05) in total isolations when tetrathionate was compared to GN Hajna (56% vs. 44%), although there was a numerical increase in lymph node isolations with GN Hajna compared to tetrathionate (52% vs. 48%). There was a significant (P<0.05) advantage of utilizing tetrathionate for isolations from cecal contents when compared to GN Hajna (68% vs. 32%). On the basis of our results, we will utilize tetrathionate for pre-enrichment of swine cecal and fecal samples.

Last Modified: 12/28/2014