Fusobacterium nucleatum involvement in adult periodontitis and possible modification of strain classification

Background: This investigation was designed to evaluate the involvement of Fusobacterium nucleatum clinical strains in adult periodontitis by subspeci es and expression of hemagglutination activity. Methods: Forty-nine Fusobacterium strains were isolated from 40 sites in 40 subjects presenting with adult periodontitis. F. nucleatum subspecies iden tification was based on the electrophoretic migration of glutamate dehydrog enase and 2-oxoglutarate reductase. Hemagglutination activity and inhibitio n by galactose were tested on sheep erythrocytes. Results: The 49 isolates belonged to the F. nucleatum species with a predom inance of the nucleatum (34.7%) followed by the vincentii (26.5%) subspecie s. In parallel, 71% of the strains belonging to the nucleatum subspecies we re preferentially associated with Porphyromonas gingivalis. Prevotella inte rmedia/ nigrescens detection was essentially correlated with identification of Fusobacterium nucleatum subspecies vincentii. No correlation was establ ished between any particular subspecies and the pathogenicity factors teste d (hemagglutination and production of short-chain fatty acids). On the othe r hand, significant predominance (65%, P = 0.017) of strongly hemagglutinat ing strains (titre greater than or equal to8 U) was observed in the sites w here Porphyromonas gingivalis, Prevotella intermedia/nigrescens and/or Camp ylobacter rectus were not detected. These strains also showed higher butyri c acid production. Conclusion: The importance of the adherence factors for Fusobacterium nucle atum strains and their multimodal aspect may indicate a higher pathogenicit y or a higher involvement of certain strains and could lead to a classifica tion of these strains, which is more closely related to their implication i n the development of periodontal disease.