Molecular genotyping of isolates of Actinobacillus actinomycetemcomitans by pulsed-field gel electrophoresis after separate digestion with Sse8387I and XhoI.

Genomic DNA from 18 Japanese clinical isolates of Actinobacillus actinomycetemcomitans was obtained from six periodontitis patients and analyzed using pulsed-field gel electrophoresis (PFGE) after separate digestion with Sse8387I and with XhoI. Three isolates from an identical patient were found to share an identical PFGE profile, and isolates from distinct patients were found to have PFGE profiles distinctly different from each other. Consequently, the 18 Japanese clinical isolates were discriminated into six distinct genotypes by means of PFGE. The genomic DNA from the other six reference strains (ATCC33384, ATCC43717, ATCC 43718, JCM2434, JCM2435 and Nig-1) was discriminated into six genotypes by the same PFGE methodology, and these six genotypes were found to be distinctly different from the six genotypes of the 18 Japanese clinical isolates described above. Serotyping demonstrated three PFGE genotypes in the serotype a strains, four the serotype b strains and three the serotype c strains. The present results clearly suggest that the PFGE procedure after separate digestion with Sse8387I and with XhoI has an excellent discriminatory power amongst strains and has a good genotypability for A. actinomycetemcomitans.