Detection of Actinobacillus actinomycetemcomitans in unstimulated saliva of patients with chronic periodontitis

Background: The use of whole saliva has shown to be promising in detecting Actinobacillus actinomycetemcomitans out of the subgingival environment. The objective of the present study was to evaluate the use of unstimulated saliva in detecting A. actinomycetemcomitans and to compare the subgingival and extra-crevicular occurrence of this pathogen in Brazilian subjects with chronic periodontitis. Methods: Sixty-six patients (mean age 38.01 +/- 9.28 years) with advanced generalized chronic periodontitis were sampled. Subgingival plaque samples were collected from eight sites per patient representing the two deepest sites of each quadrant. Samples of the mucous surfaces, including dorsal surface of the tongue and cheek, were collected with a sterile swab and placed in a microtube containing a reduced solution. Samples of unstimulated saliva were also collected in sterile tubes and 0.1 ml of whole saliva was diluted in 1 ml of reduced solution. The presence of A. actionomycetemcomitans was established using bacterial culture in trypticase soy bacitracin vancomycin selective media. Polymerase chain reaction (PCR) was used to differentiate highly from minimally leukotoxic strains in patients who presented A. actinomycetemcomitans in at least two sampled sites. Results: A. actinomycetemcomitans was isolated from 63.63% of subgingival samples, 56.06% of saliva samples, and 45.45% of samples from mucous surfaces. No statistical difference was observed between subgingival and salivary occurrence of the microorganism. Linear regression showed an association between subgingival plaque and saliva (r(2)=0.897; P = 0.015) and mucous membrane and saliva (r(2) = 0.152; P = 0.024). The same A. actinomycetemcomitans leukotoxic profile was observed in all sampled sites for a given patient. Conclusion: These results suggest that in advanced periodontitis, unstimulated saliva is representative of pooled subgingival plaque samples and its use is appropriate in the oral detection of A. actinomycetemcomitans.