Comparison of GN Hajna and tetrathionate as initial enrichment for salmonellae recovery from swine lymph nodes and cecal contents collected at slaughter.

An epidemiologic survey was conducted to determine the prevalence of salmonellae in swine from 5 farms of an integrated swine operation. The purpose of this study was to evaluate the recovery efficiencies for salmonellae from swine lymph nodes and cecal contents when GN Hajna and tetrathionate were compared as initial enrichments. Salmonellae were isolated from 61% of 645 pigs at slaughter; 324 positive cultures were from lymph nodes, and 224 were from cecal contents. Frequently, pigs had salmonellae isolated from both the lymph nodes and cecal contents. Total isolations, regardless of source, were similar for GN Hajna (247) and tetrathionate (301). There was no difference (P > 0.05) in the number of isolations from lymph nodes when GN Hajna enrichment was compared with tetrathionate enrichment (174 vs. 150). However, there was a significant (P < 0.05) advantage of utilizing tetrathionate when compared with GN Hajna for isolations from cecal contents (151 vs. 73).