|Cox, Nelson - Nac|
|RICHARDSON, L. JASON - Coca-Cola Company|
|WILSON, JEANNA - University Of Georgia|
|HARRISON, MARK - University Of Georgia|
Submitted to: Journal of Food Safety
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/22/2016
Publication Date: 9/28/2016
Citation: Cox Jr, N.A., Richardson, L., Cosby, D.E., Berrang, M.E., Wilson, J.L., Harrison, M.A. 2016. A four-quadrant sequential streak technique to evaluate Campylobacter selective broths for suppressing background flora in broiler carcass rinses. Journal of Food Safety. doi:10.1111/jsf.12311.
Interpretive Summary: There are numerous selective enrichment broths to select for use with foodborne human enteropathogens such as Campylobacter. This paper presents an easy to use technique to compare and evaluate the two most commonly used selective broths for Campylobacter in the U.S. Based on the suppression of extraneous background microflora with broiler carcass rinses, Tecra broth was more effective than Bolton’s broth.
Technical Abstract: The ecometric technique is a semi-quantitative scoring method used in the quality control of culture media in microbiology laboratories. This technique involves inoculation with defined populations of a specific culture onto solid media via a standardized chronological streaking technique, leading to ever-decreasing numbers of colonies. The objective was to evaluate the efficacy of a modified ecometric technique [four-quadrant sequential streak (FQS)] in determining undefined background microflora levels in two commonly used Campylobacter selective enrichment broths. Acquisition of natural background microflora to evaluate the technique was achieved by conducting whole carcass rinses of post-pick broilers (n=30) obtained from a commercial poultry processing plant. Rinses were introduced into Bolton and Tecra broth and incubated microaerobically at 42oC for 48 h. For the FQS procedure, 10µL from each type of sample was streaked (five individual streak lines) onto one quarter of a Campy-cefex agar plate and sequentially into the next 3 quadrants without crossing other lines. After incubation, growth of non-Campylobacter colonies on campy-cefex was expressed as absolute growth index (AGI). A significant (P<0.05) difference in background microflora suppression in the two Campylobacter enrichment broths was observed using the FQS and enumeration procedure. A positive correlation between decreasing levels of background microflora within the broths were observed as the AGI declined. The FQS procedure can be used for rapid semi-quantitative estimation of an enrichment broth’s efficacy in suppressing background microflora much easier than performing a standard enumeration procedure.