Certain bacterial species and morphotypes in localized juvenile periodontitis and in matched controls

Subgingival microflora in localized juvenile periodontitis (LJP) was examined by culture of certain bacterial species and by direct dark-field microscopy in affected and unaffected periodontal pockets of 11 patients and in their age- and sex-matched controls. Only Actinobacillus actinomycetemcomitans (A.a.) correlated to periodontal destruction and occurred most frequently at the affected LJP sites. A.a., Bacteroides intermedius and Fusobacterium nucleatum were isolated in proportions greater than 5% of the flora at the affected LJP sites, but various Actinomyces spp. at the unaffected and control sites. The proportions of straight rods, fusiforms and small spirochetes correlated to gingival bleeding tendency and were higher at the affected LJP sites than at the control sites. Certain nonpigmented Bacteroides spp. and Eikenella corrodens were never isolated when only cocci were seen at dark-field microscopy. The more complex the flora, the more frequently B. intermedius occurred. The results support a significant role for A.a. in LJP and indicate that certain bacterial species appear to prefer occurring in the complex composition of subgingival microflora.