P2-103 Overnight Incubation of Entire Broiler Carcass for Increased Detection of Salmonella

Monday, July 27, 2015
Exhibit Hall (Oregon Convention Center)
Mark Berrang , USDA, ARS,RRC , Athens , GA
Nelson Cox , USDA-ARS-USNPRC , Athens , GA
Douglas Cosby , USDA - Agriculture Research Service , Athens , GA
Sandra House
Jonathon Frye
Charlene Jackson , USDA-ARS-RRC , Athens , GA
Introduction: Broiler carcasses are generally sampled for presence of human pathogens such as Salmonella by whole carcass rinse and enrichment of a portion of the rinse. This may leave firmly attached cells out of the analysis potentially leading to false negative results.

Purpose: The objective of this study was to compare a traditional whole carcass rinse and culture of an aliquot to an overnight incubation of the entire carcass in the rinse liquid. 

Methods: On each of 5 replicate sample days (5 flocks), 8 broiler carcasses were collected after chilling in a commercial slaughter plant.  Each carcass was subjected to a whole carcass rinse in 400 ml buffered peptone water (BPW).  A 30 ml aliquot was removed and placed in sterile cups.  Cups and carcasses in broth were both incubated (35°C, 24 h) to pre-enrich for Salmonella.  All incubated pre-enrichment broths were selectively enriched in RV and TT broth (42°C, 24 h) from which XLT4 and BGS plates were streaked and incubated (35°C, 24 h).  Suspect colonies were confirmed as Salmonella by biochemical and serological methods.

Results: Salmonella was found on significantly (P < 0.01) more carcasses when sampled by carcass enrichment (29+/40) compared to aliquot enrichment (4+/40).  Three of five flocks were found to have 1 or 2 positive carcasses by aliquot enrichment; in those flocks every carcass was positive when fully enriched.  Even in flocks where all aliquot enrichments were negative, some carcasses (1 or 4) were found to be positive. 

Significance: A broiler carcass sampling method that includes enriching the entire carcass allows detection of Salmonella that can be missed by enriching only an aliquot of the rinsate providing a more sensitive method.