Genotypic characterization of Actinobacillus actinomycetemcomitans isolated from periodontitis patients by arbitrarily primed polymerase chain reaction.

Actinobacillus actinomycetemcomitans is one of the most suspected pathogens in the initiation and progression of juvenile periodontitis and severe adult periodontitis. The aim of the present study was to investigate the genotypic characterization of A. actinomycetemcomitans using arbitrarily primed polymerase chain reaction (AP-PCR). AP-PCR was applied to 143 A. actinomycetemcomitans strains, including 8 reference strains and 135 clinical strains isolated from 43 unrelated Japanese periodontitis patients. The DNA fragment patterns obtained using a single 10-mer primer with random sequence (OPA-07) for these strains allowed the recognition of 10 distinct AP-PCR groups that correlated to some extent with serotypes. AP-PCR group VIII was significantly (P < 0.05) observed in deep (> 5 mm) periodontal pockets. Group II was exclusively detected in deep pockets. However, a clear relationship was not observed between AP-PCR genotypes and various periodontal status. Only one genotype was found within individual oral cavity/single-infected site, except one case in which the patient harbored two AP-PCR genotypes. The AP-PCR patterns of the A. actinomycetemcomitans isolates recovered from the site after periodontal treatment remained identical. These results demonstrate genetic diversity among the investigated population and a clonal nature in a periodontal patient of A. actinomycetemcomitans by AP-PCR. Furthermore, it could be inferred that a certain AP-PCR genotype(s) of A. actinomycetemcomitans is more important in the pathogenesis of periodontal diseases.