MOLECULAR CHARACTERIZATION AND GASTROINTESTINAL TRACT ECOLOGY OF COMMENSAL HUMAN FOOD-BORNE BACTERIAL PATHOGENS IN THE CHICKEN
Location: Poultry Microbiological Safety Research
Title: Salmonella-positive broiler carcasses contaminated by multiple serotypes
Submitted to: International Poultry Scientific Forum
Publication Type: Abstract Only
Publication Acceptance Date: October 15, 2010
Publication Date: January 24, 2011
Citation: Cox Jr, N.A., Cray, P.J., Richardson, L.J., Buhr, R.J., Cason Jr, J.A. 2011. Salmonella-positive broiler carcasses contaminated by multiple serotypes. International Poultry Scientific Forum. 258P, P.74 (ABST).
Many laboratories that routinely sample broiler carcasses for Salmonella are primarily interested only in determining the presence or absence of Salmonella, so only one colony-forming unit may be selected. The objective of this study was to select several colonies from each of four selective plates to determine what percent of positive carcasses were contaminated with multiple Salmonella serotypes. Broiler carcasses were procured directly from a commercial processing plant post-chilling, individually bagged and transported on ice to the laboratory. Each carcass was rinsed with 100 mL of 1% buffered peptone water for 1 minute and the rinsate collected and incubated for 24 h at 37oC. A 1 mL aliquot was inoculated into Gram-Negative (GN) and tetrathionate (TT) broths. After 24 h at 37oC, 0.1 mL of GN was transferred to Rappaport-Vassiliadis (RV) media and after 48 h, 0.1 mL of the TT was transferred to RV. After incubation two different selective agar plates (Brilliant Green Sulfa and Xylose-Lysine-Tergitol4) were streaked for isolation from the RV tubes. From the 4 incubated plates a maximum of 3 colonies (if available) were selected from each and standard confirmational procedures for Salmonella were performed. From a total of 49 positive carcasses, 7 (14.3%) had only one serotype, 17 (34.7%) had two, 18 (36.7%) had three, 6 (12.2%) had four, and 1 (2%) had five different serotypes. Therefore, over 85% of the Salmonella positive broiler carcasses had multiple serotypes and more than likely many other serotypes went undetected. S. Kentucky was the most frequently detected serotype, accounting for approximately 30% of the isolates. Six serotypes (Kentucky, Berta, Kiambu, Mbandaka, Heidelberg, Senftenberg) accounted for 92.7% of the 124 isolates. On only 11/49 samples (22.4%) did both plating media yield the same serotypes, for the other 38 positive samples there were differences between the plating media. This limited study demonstrates the variability of detecting individual serotypes even when only two plating media are used.