Improvement of modified charcoal-cefoperazone-deoxycholate agar by addition of potassium clavulanate for detecting Campylobacter spp. in chicken carcass rinse

•Modified charcoal-cefoperazone-deoxycholate agar (mCCDA) was improved by supplementation with potassium clavulanate.•The ability of the supplemented medium to isolate Campylobacter from chicken carcass rinse was compared with that of normal mCCDA.•Modification of mCCDA with potassium clavulanate yielded significantly (p < 0.05) better isolation rate and selectivity than that achieved when using normal mCCDA.

The presence of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli (E. coli) in raw poultry is one of the most common factors that interfere with the isolation of Campylobacter by cefoperazone-based selective agar. The performance of modified charcoal-cefoperazone-deoxycholate agar (mCCDA) was improved by addition of an ESBL inhibitor, potassium clavulanate (0.5 mg/L). The ability of the supplemented medium (C-mCCDA) to detect Campylobacter species from chicken carcass rinse was compared with that of normal mCCDA. The isolation rate using C-mCCDA was significantly (p < 0.05) higher compared with that using mCCDA (C-mCCDA, 67 out of 120; mCCDA, 38 out of 120). Furthermore, the selectivity of the C-mCCDA as assessed by comparing the number of contaminated plates (C-mCCDA, 44 out of 120; mCCDA, 110 out of 120) and growth index (C-mCCDA, 1.76; mCCDA, 2.79) of competing flora was also better (p < 0.05) than that of mCCDA.