Laboratory and clinical comparison of preservation media and transport conditions for survival of Actinobacillus actinomycetemcomitans

The capacity of clinical isolates and type strains of Actinobacillus actinomycetemcomitans to survive in a new transport medium (AaTM), phosphate-buffered saline (PBS) and Ringer's solution (RS) was evaluated. The effects of exposure to air, transportation time and temperature on viability were also studied. In addition, the culture of A. actinomycetemcomitans from subgingival plaque of patients with different forms of periodontitis was quantified. The results following storage in AaTM, PBS and RS showed that A. actinomycetemcomitans survived better in AaTM than in PBS or RS when transportation times exceeded 20-22 h, and that survival was enhanced by storage at below 12°C. Serotype b strains of A. actinomycetemcomitans were able to survive better than either serotype a or c. In the clinical study the optimal transportation conditions for subgingival plaque containing A. actinomycetemcomitans were AaTM at a temperature of 8°C for 24 h under anaerobic conditions. These conditions resulted in a high survival and isolation rate for A. actinomycetemcomitans without inhibition of the other periodontopathic bacteria isolated from deep periodontal pockets. These findings have practical implications for future multicentre clinical trials in which the transportation of oral specimens over relatively long distances and at different ambient temperatures during various periods of the year are required.