Development of a Selective Agar for Improving Campylobacter jejuni Detection in Food

Abstract

Background: Campylobacter jejuni is a major gastroenteritis-causing foodborne pathogen. However, it is difficult to isolate when competing bacteria or cold-damaged cells are present. Objective: Herein, a medium (Campylobacter selective agar, CSA) was developed and supplemented with catalase, L-serine, L-cysteine, and quercetin for the selective detection of C. jejuni in food. Method: The C. jejuni-detection efficiency in media broth and chicken tenders was evaluated. The pathogen was enumerated on modified charcoal-cefoperazone-deoxycholate agar (mCCDA), CSA supplemented with 4 mu M catalase (CSA-C4), 8 mu M catalase (CSA-C8), 20mM L-serine (CSA-S20) or 50mM L-serine (CSA-S50), and mCCDA supplemented with 0.5mM L-cysteine (mCCDA-LC0.5), 1mM L-cysteine (mCCDA-LC1), 40 mu M quercetin (mCCDA-Q40) or 320 mu M quercetin (mCCDA-Q320). The detection efficiency was then evaluated by counting colonies on the selective agar media. Quantitative assessment was also performed using chicken and duck carcasses. Results: The C. jejuni detection efficiencies were higher (P < 0.05) in the groups CSA-C4 or CSA-C8, and CSA-S20 or CSA-S50, than mCCDA, and the detection efficiencies were maintained even in the presence of Acinetobacter baumannii, a competing bacterium. In the quantitative test, CSA-C8 and CSA-S50 demonstrated higher C. jejuni-detection efficiencies than mCCDA (control). Conclusions: Therefore, CSA-C8 and CSA-S50 improved the detection efficiency of C. jejuni in poultry products by promoting the recovery of cold-damaged cells. Highlights: When using CSA-C8 or CSA-S50 developed in this study for detection of C. jejuni in food, detection efficiency was higher than mCCDA.