[Phenotypic variation in Actinobacillus actinomycetemcomitans].

Objective: To investigate the colony variation in Actinobacillus actinomycetemcomitans (Aa) from rough to smooth and recognize its different morphology during laboratory translations.

Methods: Primary strains isolated from subgingival plaque of two juvenile periodontitis patients were repeatedly subcultured on agar plates and broth; for broth culture, every generation was translated in broth and on solid medium separately to observe the corresponding morphologies of Aa grow in broth.

Results: Three smooth strains of Aa from the broth culture were obtained.