Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 11/9/2003
Publication Date: 11/9/2003
Citation: ROSTAGNO, M.H., GAILEY, J.K., HURD, H.S., MCKEAN, J.D. EFFECT OF CULTURE METHODS ON INVESTIGATIONS OF SALMONELLA ENTERICA ECOLOGY AND EPIDEMIOLOGY IN SWINE. CONFERENCE OF RESEARCH WORKERS IN ANIMAL DISEASES. 2003. ABSTRACT P. 77.
Technical Abstract: Four bacteriological culture methods were comparatively evaluated for their ability to isolate Salmonella from swine fecal samples (n = 100). Methods A, B, and C consisted of primary enrichment in GN-Hajna, Tetrathionate, and Rappaport-Vassiliadis broths (respectively), followed by secondary enrichment in Rappaport-Vassiliadis broth. Method D consisted of primary enrichment in GN-Hajna broth with Novobiocin, followed by double secondary enrichment in Rappaport-Vassiliadis and Tetrathionate broths, and a combined post-enrichment in M broth with Novobiocin. After the secondary enrichment (Methods A, B, and C) or post-enrichment (Method D) steps, isolation was conducted on XLT-4 agar plates. None of the methods was able to isolate Salmonella from all positive samples. The relative sensitivity of the culture methods evaluated was; 82% for method A, 94% for method B, 95% for method C, and 78% for method D. The comparison of sensitivities showed that methods B and C performed significantly better (p < 0.05) than methods A and D. Although relative sensitivities of methods B and C were equal, from the 89 positive samples detected by both, 35 (39.3%) had different serovars (no match) isolated by each method. This study demonstrates that culture methods affect investigations on ecology and epidemiology of S. enterica in swine, due to their diverging ability to detect positive samples and different serovars. Although culture methods constitute the basis for Salmonella investigations, there is still a need for standardization of the methods applied, as well as continuous improving and comparative studies in order to establish parameters for comparison of results from different studies.