Intra-familial distribution of Fusobacterium nucleatum strains in healthy families with optimal plaque control

Fusobacterium nucleatum, a Gram-negative anaerobic rod associated with peri odontal disease, is also found in healthy individuals and is considered par t of the indigenous oral microflora. Although intra-familial transmission o f periodontal pathogens has been documented, there are no data relating tra nsmission of F. nucleatum. This study investigated the distribution of F. n ucleatum strains in 4 strictly healthy families. 32 F. nucleation strains w ere isolated from 19 individuals (8 parents and 11 children aged 1-13 years ). DNA was extracted and digested with the restriction endonucleases EcoRI, TaqI and HindIII. The digests were separated by electrophoresis through 0. 8% agarose gels at 40 V overnight, in TEE buffer containing I mu g/ml ethid ium bromide, and photographed. The DNA was transferred to nylon filters by Southern blotting and hybridized with a digoxigenin labelled E. coli rRNA p robe (Kit Dig DNA Labelling mixture - Boehringer). Probed DNA was visualize d colorimetrically (CSPD Luminescent Detection Kit Boehringer) and photogra phed (Amersham). We found that 10/ 11 children shared identical ribotypes w ith at least one of their respective parents. Some of the children also hat -bored a unique additional ribotype. On the basis of indistinguishable rest riction endonuclease and ribotype patterns these results support the hypoth esis that intra-familial transmission of F. nucleatum is possible.