Intraoral distribution of Actinobacillus actinomycetemcomitans in young adults with minimal periodontal disease

The aim of the present study was to investigate the intraoral distribution of Actinobacillus actinomycetemcomitans in young adults with minor signs of periodontal disease but harboring the organisms in the oral cavity. 17 hea lthy volunteers, 20 to 27 years of age, participated, Samples from mucosal surfaces of the ore-pharyngeal cavity and saliva (n= 221) as well as subgin gival plaque from every tooth in (n= 477) were selectively cultivated for A . actinomycetemcomitans c . Species identity and presence of the leukotoxci n encoding gene, ltxA, were checked by multiplex polymerase chain reaction. Moreover, the leukotoxin promoter region was analyzed. No isolate harbored a 530 bp deletion in the promoter region of the leukotoxin gene, signaling minimally toxic strains. 42.1 +/- 30.4%, extracrevicular and 34.4 +/- 29.5 % subgingival samples were culture-positive. In extracrevicular samples. th e organism could easily be recovered from check mucosa (62%), saliva (59%) and the palatal tonsils (41%). Mean log-transformed numbers of A. actinomyc etemcomitans colony forming units (CFU/ml) in culture-positive material ran ged between 1.8 from the hard palate and 2.3 from 10 mul saliva. The highes t prevalence in subgingival plaque was observed at maxillary 3rd molars (55 %) followed by maxillary lateral incisors (50%) and mandibular 3rd molars ( 41%). Mean log-transformed counts of CFU/ml ranged between 2.2 at maxillary 3rd molars and 3.4 at upper central incisors. When adjusted for jaw, site and tooth type, the odds of isolating higher numbers of the organism were i ncreased with every mm probing depth by a factor of 1.35 (p < 0.05). The od ds ratio for bleeding on probing was 1.38. Thus, in this young adult popula tion with minor periodontal disease, A. actinomycetemcomitans was mainly as sociated with some deviation from gingival health. Of concern might be a mi niority of subjects (29%) with an extremely wide distribution of the organi sm in the oral cavity.