Actinobacillus actinomycetemcomitans is a Gram-negative oral bacterium which has been implicated in the etiology of localized
juvenile periodontitis. In this study, 403 subjects from four study groups were examined for A actinomycetemcomitans in subgingival
dental plaque. Samples pooled from at least six periodontal sites were included from each subject. A actinomycetemcomitans was detected in 28 of 29 localized
juvenile periodontitis patients but in only 15% of the other subjects including 28 of 134
adult periodontitis patients, 24 of 142 periodontally healthy subjects and 5 of 98
insulin dependent juvenile diabetics with varying degrees of
gingivitis. A actinomycetemcomitans isolates from members of five families with localized
juvenile periodontitis patients were biotyped on the basis of variable fermentation of
dextrin, maltose,
mannitol and
xylose and serotyped by indirect immunofluorescence using serotype specific rabbit
antisera. Individuals within a family all harbored A actinomycetemcomitans of the same biotype and serotype. However, even in families with individuals heavily infected with A actinomycetemcomitans, some family members did not appear to be infected with the organism. The apparent poor transmissibility of A actinomycetemcomitans between individuals may, in part, explain the overall low prevalence of localized
juvenile periodontitis and the familial pattern of the disease. The high prevalence of A actinomycetemcomitans in the subgingival plaque of localized
juvenile periodontitis patients, compared to the much lower prevalence in other patient groups, supports the hypothesis that A actinomycetemcomitans is an etiologic agent in this
periodontal disease.(ABSTRACT TRUNCATED AT 250 WORDS)