Submitted to: International Symposium on Epidemiology and Control of Salmonella in Pork
Publication Type: Abstract Only
Publication Acceptance Date: 9/5/2001
Publication Date: N/A
Technical Abstract: The present study evaluated culture methods to optimize detection and isolation of a wide range of Salmonella serovars from feces. Fecal samples were obtained from cows, horses, and pigs. All fecal samples were suspended in saline-buffered phosphate and homogenized prior to media inoculation. Two pre-enrichment (buffered peptone water [BP], GN broth, Hajna), 3 selective enrichment (Rappaport-Vassiliadis [RV] broth, selenite cystine [SC] broth, tetrathionate [T] broth), and 5 selective plating (brilliant green sulfa [BGS], xylose lysine tergitol 4 [XLT4], Hektoen enteric [HE], Rambach [RA], Chromagar Salmonella [CAS]) media were evaluated. Salmonella enterica serovars Typhimurium and Choleraesuis (both antibiotic) were inoculated individually, in combination and seeded in select fecal samples as positive controls. Samples were quantified prior to enrichment, after pre-enrichment and after selective enrichment; sub-samples were serially diluted and plated on tryptone soya, MacConkey's, and selective plating agars. Colonies were counted on selective agars as presumptive Salmonella (PSC) or non-Salmonella (NSC). Differentiation of PSC and NSC was more difficult on BGS and HE and best on CAS, while XLT4 and HE favored H2S producing serovars. Both pre-enrichment media increased PSC detection. RA detected colony morphological differences among serovars. No single method appeared to be adequate to investigate Salmonella serovar ecology. Future research will use two selective enrichments, RV and SC, after BP pre-enrichment with isolation on XLT4 and CAS followed by RA as a differentiation indice.