A new selective medium for Aggregatibacter actinomycetemcomitans from saliva sample

Objectives: Aggregatibacter actinomycetemcomitans is considered a major etiologic bacterium of localized aggressive periodontitis. We developed a new selective medium designated as AASM (J. Periodont Res. in press), for isolation of A. actinomycetemcomitans from subgingival exudate of periodontal sites with endodontic paper point. When the saliva samples were applied to AASM medium, the selection of A. actinomycetemcomitans was not efficient. Saliva is the most appropriate clinical specimen material, because it is easy to collect anywhere without patient's pain and no need any special equipment. Purpose of this study was to develop a new selective medium for detection of A. actinomycetemcomitans from saliva sample.

Methods: The sensitivity of antibiotics were examined using reference strains (serotypes a to f) of A. actinomycetemcomitans. The recovery of the new selective medium, designated as AASMT, were calculated and compared with AAGM and AASM medium. For examination of clinical efficacy, stimulation saliva samples were collected from volunteers of healthy persons of periodontium and chronic periodontal patients (pocket depth: more than 4mm). For identification of A. actinomycetemcomitans from clinical samples, gram staining, catalase production and PCR analyses were examined. To examine frequency of serotype, serotype-PCR and Ouchterony were performed.

Results: All serotypes (a to f) of A. actinomycetemcomitans strains grew well and the average growth recovery of A. actinomycetemcomitans on a new AASMT medium was 92.7% (79.0-108.1%) of that on AAGM. The exclusive rate of other bacteria was 99.99% in saliva sample on AASMT. A. actinomycetemcomitans was not detected in periodontal healthy persons and detected in 10% in chronic periodontal patients.

Conclusions: This study has shown that the new selective medium was highly selective for A. actinomycetemcomitans, eliminated possible false-positive results and useful for isolation of A. actinomycetemcomitans from saliva samples.