[Detection of Campylobacter species by using polymerase chain reaction and nonradioactive DNA probes. III. DNA probe for identification of C. laridis].

The development of a rapid and specific DNA probe assay for identification of Campylobacter species, including C. jejuni, C. coli, C. laridis, C. fetus, and C. hyointestinalis is important in determining the precise diagnosis of Campylobacter infections. Sequence data of our previous studies for a 240-base DNA fragment was used to select primers and probes conjugated to alkaline phosphatase, complementary to a portion of DNA between primers. However, a 21-base probe (CL (1)) tested here for detection of C. laridis was cross-reactive with PCR-amplified fragments of C. jejuni, C. coli and C. hyointestinalis, although it was not reactive with C. fetus and C. fetus subsp. fetus. To solve this problem, further modifications of the probe were therefore made to improve the specificity for those particular species. A second 21-base probe with a single base-substitution (CL (2)) and a third 20-base probe (CL(3)) were ineffective for identification of C. laridis, too. A fourth 20-base probe with a single base substitution (CL(4)) was a significant improvement over the results obtained by other three probes specifically to detect C. laridis, Thus, the alkaline phosphatase-labeled probe method developed so far is an interesting alternative without access to radioisotopes for clinical laboratories for identification of Campylobacter species, including C. jejuni/coli/hyointestinalis, C. laridis, and C. fetus/fetus subsp. fetus.