Improved PCR detection of Campylobacter jejuni from chicken rinses by a simple sample preparation procedure

Many food samples and enrichment media are inhibitory to the PCR, thereby lowering its detection capacity. A simple sample preparation method based on buoyant density centrifugation was examined for its application in PCR detection of Campylobacter jejuni from chicken rinse samples. Bacterial cells were spiked at different levels in a mixture of Preston broth and chicken rinse (4:1 ratio) and 0.9 ml of these mixtures were layered over 0.6 ml of gradient medium made from Percoll. PCR sensitivity for bacterial samples treated with this procedure was approximately 10-100 times higher than for samples without treatment. This sample preparation method allowed for the detection of C. jejuni from 26 of 31 naturally contaminated chicken samples after a 20-24-h enrichment period in Preston broth, compared with only 14 positives for untreated samples. In addition, the effect of Oxyrase on the growth and PCR detection of C. jejuni was examined. While Oxyrase significantly enhanced the growth and the PCR signals of C. jejuni in pure culture, it appeared not to improve the PCR detection of C. jejuni in naturally contaminated chickens.