Modification of Karmali Agar by Supplementation with Potassium Clavulanate for the Isolation of Campylobacter from Chicken Carcass Rinses

초록

The detection ability and selectivity of Karnali agar was improved by supplementation of an extended-spectrum beta-lactamase inhibitor, potassium clavulanate. The optimum concentration of potassium clavulanate (0.5 mu g/ml) in Karmali agar was determined by inoculation of 50 Campylobacter and 30 extended-spectrum beta-lactamase producing E. colt strains onto normal and modified Karmali agar containing various concentrations of the agent. Eighty retail carcasses were rinsed with 400 ml of buffered peptone water. The rinse samples were enriched in 2 x blood-free Bolton enrichment broth at 42 degrees C for 48 h and then were streaked onto normal and modified Karmali agar containing 0.5 mu g/ml potassium clavulanate. The suspicious colonies were subcultured on Columbia blood agar and confirmed by colony PCR. In chicken carcass samples, the modified Karmali agar showed a significantly greater isolation rate than normal Karnali agar (42.5 versus 21.3%; P < 0.05). Furthermore, the selectivity of the modified Karnali agar was also significantly higher (P < 0.05) than that of the normal Karnali agar, as seen by comparison of the number of contaminated agar plates (83.8 versus 97.5%) and the growth index (1.67 versus 2.91) of the non-Campylobacter colonies.

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