INTRA-FAMILIAL TRANSMISSION AND DISTRIBUTION OF PREVOTELLA-INTERMEDIAAND PREVOTELLA-NIGRESCENS

The periodontal bacteria Prevotella intermedia and Prevotella nigresce ns have been recently separated from each other. The purpose of this s tudy was to investigate the distribution and routes of transmission of these bacteria among family members. Seven patients with moderate to severe periodontitis were selected. These probands, their spouses and 14 of their children were investigated. The presence of Pr. intermedia and Pr, nigrescens was determined by culture techniques in pooled sub gingival plaque samples, in the saliva, on the tongue, tonsils and buc cal mucosa. Differentiation of Pr. intermedia and Pr. nigrescens was p erformed by enzyme electrophoretic mobility. From all 7 patients, as w ell as 4 spouses and 3 of the children, Pr. intermedia could be isolat ed. Pr. nigrescens was found in 2 of the 7 patients, in 5 of the spous es and in 5 of the 6 children aged 5-10 yr. In the 8 children aged 0-4 yr both species were seldom isolated. These data are in accordance wi th earlier findings that Pr. intermedia is associated with periodontit is and Pr. nigrescens with a relatively healthy periodontal condition. Ribotyping of bacteria was performed by hybridization of HindIII rest riction endonuclease digests of chromosomal DNA with ribosomal DNA. Is olates from unrelated individuals always had distinct ribotypes. Indis tinguishable ribotypes of Pr. intermedia and Pr. nigrescens were found both among married couples and among parents and children. This indic ates that intrafamilial transmission of Pr. intermedia and Pr. nigresc ens is possible both between adults and between parents and children.