Detection of Actinobacillus actinotnycetemcomitans, Porphyromonas gingivalis, and Bacteroides forsythus in an A. actinomycetemcomitans‐Positive Patient Population

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Abstract
A population of 33 subjects were selected on the basis that all had tested positive for A. actinomycetemcomitans at some time during the prior 7 years. Most subjects (31/33) belonged to families with a proband with confirmed localized juvenile periodontitis (JP); however, most subjects had no evidence of the typical lesions associated with JP. Two additional subjects with rapidly progressive periodontitis, known to be positive for A. actinomycetemcomitans, were also recruited. The patients with a history of JP had been treated, but were no longer enrolled in a regular maintenance program. With 3 exceptions, the subjects had not received any dental treatment or antibiotics in the past 3 months. One aim of the study was to determine the prevalence of A. actinomycetemcomitans, P. gingivalis, and B. forsythus in this population. The main purpose was to compare the relative sensitivity of various methods for detecting these periodontal pathogens. Pooled subgingival plaque samples were collected from all the mesial surfaces and aliquots of the suspension processed for the detection of A. actinomycetemcomitans by culture and indirect immunofluorescence (IF) to serotypes a, b, and c. P. gingivalis and B. forsythus were monitored with a DNA probe and IF. With culture, A. actinomycetemcomitans was detected in 39.4% of the samples, at a mean level of 0.64% of the cultivable counts. With IF, A. actinomycetemcomitans was detected in 81.8% of the samples, at levels of 0.40, 0.79, and 0.17% of the total counts for serotypes a, b and c respectively. Overall, IF was more likely to detect A. actinomycetemcomitans, P. gingivalis, and B. forsythus than any of the other methods. However, many of the levels of recovery were low. If critical levels of recovery are necessary for disease onset and the culture or probe is sensitive enough to detect the target species at these levels, then the greater sensitivity of IF may not be needed. Nevertheless, until these critical levels are more clearly defined the greater sensitivity of IF may be advantageous. J Periodontol 1995; 66:158–164.