Actinobacillus (Haemophilus) actinomycetemcomitans in periodontal disease

Actinobacillus (Haemophilus) actinomycetemcomitans is a facultatively anaerobic, gram-negative coccobacillus which is a possible etiological agent in juvenile periodontitis (JP). In this study, bacterial flora, especially the occurrence of A. actinomycetemcomitans, in the periodontal pockets of one juvenile with gingivitis (G), one JP patients, five rapidly progressive periodontitis (RP) patients and one adult periodontitis(AP) patient, and one adult with healthy periodontium was investigated using a blood agar medium and a selective medium for A. actinomycetemcomitans. Eight hundred and sixty-five bacteria were isolated from the periodontal pockets, examined for their gram-stain, cell morphologies, relations to O2 and CO2 and catalase reaction, and divided into 21 groups on the basis of these characters. Among the isolates, 604 isolates were further characterized biochemically and identified. A. actinomycetemcomitans was found as 0.2% of the flora of a site in the JP patient, as 9% of the flora of a site in the G patient, and as 19% and 1%, respectively, of the flora of a site in the two RP patients. However, the organism was not detected in another lesion site of the JP patient. In our JP and RP patients, Fusobacterium, Wolinella, Streptococcus, and obligately anaerobic, gram-positive cocci were frequently found at high levels. The bacterial flora of the G and AP patients were more heterogeneous and included Bacteroides at relatively high proportions. These results indicate that A. actinomycetemcomitans is not always associated with JP but occurred in some patients with RP and G.