Development and clinical application of DNA probe specific for Peptostreptococcus micros. 
P. micros is thought to be an important pathogen in the etiology of certain inflammatory lesions, however, the role of this microorganism is uncertain due to the lack of rapid and reliable method to identify this species.  The purpose of this study was to develop a DNA probe specific for the detection of P. micros in order to evaluate its prevalence in oral infectious lesions.  The whole genomic DNA from P. micros was partially digested and inserted into the vector pUC 13.  Four recombinant clones were selected, purified and screened against reference strains of Peptostreptococcus species to check the species specificity and then applied to clinical isolates.  The sensitivity and specificity of the DNA probe for P. micros was 99.2% and 100%, respectively.  P. micros could be detected in 7.2% of subgingival dental plaques from the patients with adult periodontitis and in 16.1% of the endodontic lesions with periapical pathosis.  In the endodontic lesions, there was a good correlation between the clinical symptoms and the presence of P. micros.  These data strongly suggested that the DNA probe can be useful in the detection of P. micros and that this microorganism is important in certain periodontal and endodontic lesions.