Application of the 5′-Nuclease PCR Assay in Evaluation and Development of Methods for Quantitative Detection ofCampylobacter jejuni

Authors:
Publisher website
Google Scholar
Abstract
Campylobacter jejuniis recognized as a leading human food-borne pathogen. Traditional diagnostic testing forC. jejuniis not reliable due to special growth requirements and the possibility that this bacterium can enter a viable but nonculturable state. Nucleic acid-based tests have emerged as a useful alternative to traditional enrichment testing. In this article, we present a 5′-nuclease PCR assay for quantitative detection ofC. jejuniand describe its evaluation. A probe including positions 381121 to 381206 of the publishedC. jejunistrain NCTC 11168 genome sequence was identified. When this probe was applied, the assay was positive for all of the isolates ofC. jejunitested (32 isolates, including the type strain) and negative for all otherCampylobacterspp. (11 species tested) and several other bacteria (41 species tested). The total assay could be completed in 3 h with a detection limit of approximately 1 CFU. Quantification was linear over at least 6 log units. Quantitative detection methods are important for both research purposes and further development ofC. jejunidetection methods. In this study, we used the assay to investigate to what extent the PCR signals generated by heat-killed bacteria interfere with the detection of viableC. jejuniafter exposure at elevated temperatures for up to 5 days. An approach to the reduction of the PCR signal generated by dead bacteria was also investigated by employing externally added DNases to selectively inactivate free DNA and exposed DNA in heat-killed bacteria. The results indicated relatively good discrimination between exposed DNA from deadC. jejuniand protected DNA in living bacteria.

This publication has 43 references indexed in Scilit: