M.S. (Master of Science)
Department of Biological Sciences
Salmonella; Food contamination; Sausages; Chicken industry
Two preenrichment broths, universal (UP) and lactose (LB), two selective enrichment broths, tetrathionate brilliant green (TBG) incubated at 42?C, and selenite cystine (SC) incubated at 35?C, and 5 plating media: xylose lysine deoxycholate with 5 mg/Iiter of novobiocin (XLD-N), bismuth sulfite (BS), Hektoen enteric with 80 mg/Iiter of novobiocin (HE-N), double modified lysine iron agar (DMLIA) and brilliant green sulfa with 15 mg/Iiter of novobiocin (BGS- N), were evaluated to determine their efficacies for the recovery of salmonellae from 200 samples of naturally contaminated fresh chicken and pork sausage. UP has been investigated by other researchers for the simultaneous recovery of Listeria and Salmonella in food products to save time and expense instead of using separate preenrichment broths. In this study, Salmonella was undetected in 22% of samples with LB and 27% of samples with UP. These results suggest that the utilization of the two preenrichment broths, LB and UP, is warranted in the recovery of Salmonella from fresh chicken and pork sausage. Significantly more samples were positive for Salmonella when enriched in TBG at 42?C as compared to SC at 35?C (P<0.05). Salmonella was undetected in only 3% of samples when SC was eliminated as an enrichment medium, suggesting that the benefit of using SC is questionable. The plating medium DMLIA has been recommended by the USDA as an alternative to XLD. Comparing the five plating media, salmonellae were recovered from 100% of positive samples when the combination of XLD-N and BGS-N was utilized, whereas DMLIA and BS showed the lowest recovery rates. Of the methods tested, the best procedure for the recovery of salmonellae in fresh chicken and pork sausage includes preenrichment in both LB and UP, enrichment in TBG at 42?C, and plating with XLD-N and BGS-N.
Vestergaard, Ellen, "Evaluation of various preenrichment broths and other plating media for isolating salmonellae from naturally contaminated fresh chicken and pork sausage" (1996). Graduate Research Theses & Dissertations. 2945.
vii, 67 pages
Northern Illinois University
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