Two-stage Enrichment Method for Isolating Campylobacter spp. in Imported Chicken Samples

Abstract

We investigated the Campylobacter isolation method from retail imported chicken samples. Campylobacter spp. was isolated from 26 of 100 samples (26.0%) using Preston enrichment broth, whereas 13 of 100 samples (13.0%) using Bolton broth. It is suggested that Bolton broth is not suitable for the isolation of Campylobacter spp. when meat remains in the culture medium, because of its weakness in sustaining the growth of other bacterium. Isolation rate of Campylobacter spp. was increased (p<0.05) to 42.0% when 1 ml of Preston culture medium was inoculated to another sample of Preston broth (10 ml) after incubation for 24 hours, and similarly, isolation rate was raised (p<0.05) to 33.0% when 1 ml of Bolton culture medium was inoculated to Preston broth. Two-stage enrichment that is inoculation of Bolton culture medium to Preston broth following pre-incubation (for 24 hours) of whole emulsion samples, is useful for frozen chicken samples, such as imported chickens, in which the bacterial number of Campylobacter spp. is supposed to be reduced during the process of freezing or thawing.