Submitted to: Poultry Science
Publication Type: Abstract Only
Publication Acceptance Date: 11/13/2015
Publication Date: 2/1/2016
Citation: Cosby, D.E., Cox Jr, N.A., Berrang, M.E. 2016. A simplified dilution method for detection of Campylobacter in broiler ceca [abstract]. Poultry Science. 95(E-Suppl 1):273.
Interpretive Summary: none.
Technical Abstract: Campylobacter species, a leading foodborne pathogen, is linked to poultry. Development of intervention strategies depends on the ability to rapidly and consistently recover and estimate the number of bacteria present. The objective of this experim ent was to validate a semi-quantitative method for detection of Campylobacter in broiler ceca. Viscera from a local processing plant were collected at the evisceration line, placed into sterile bags and transported on ice to The US Poultry National Research Center. Ceca (n=20) were separated, divided into six equal pieces and two pieces were placed into each of 3 stomacher bags. Ceca portions were diluted 1:3 (w/v) with Tecra® broth (TB) and inoculated with approximately 101, 103 or 105 cfu/mL gentamicin resistant C. coli (CCGR). Inoculum numbers were confirmed by plate count. Ceca portions were stomached for 60 s and CCGR were enumerated using two methods. First method: Serial dilutions were performed in 0.85% NaCl, plated onto Campy-cefex agar with 200 ppm gentamicin (GCefex). Following microaerobic incubation at 42oC for 48 h, characteristic colonies were counted and the numbers were log transformed. Second method: The 3-swab method was completed. Briefly, two swabs were placed in the diluted ceca, one swab was used to apply material to a GCefex plate (A plate) a second swab was placed into 9.9 mL of TB without supplements and vortexed; a third swab was inserted into the TB and used to apply diluted sample onto a second GCefex plate (B plate). For negative samples (A and B plates), a fourth swab was placed into the enriched sample bag and streaked onto a third GCefex plate (C plate) and incubated as above. A paired T-test was used to compare counts found by both methods to the number of cells inoculated into the cecal sample. At all inoculum levels, the standard serial dilution method resulted in significantly fewer CCGR recovered than were inoculated. By contrast, the simplified method recovered all inoculated CCGR when the inoculum was at either the 103 or 105 levels. At an inoculum of 101, neither method was efficient. These results suggest that the simplified 3 swab method is adequate to recover Campylobacter from broiler ceca, especially when colonized at =103 cfu/g.