Transmission of Actinobacillus actinomycetemcomitans in families of adult periodontitis patients

At present Actinobacillus actinomycetemcomitans is regarded as an important microorganism in the etiology of some forms of periodontitis. The purpose of the present investigation was to study the number of Restriction Endonuclease Analysis (REA)-types present in the oral cavity of A. actinomycetemcomitans positive subjects and to study the possibility of transmission of A. actinomycetemcomitans within families of adult periodontitis patients. DNA of A. actinomycetemcomitans isolates was digested with a combination of the restriction endonucleases PstI and BamHI, after which the DNA fragments were separated by agarose gel-electrophoresis. To study the number of REA-types, multiple A. actinomycetemcomitans isolates obtained from 8 different sites in the oral cavity of five subjects were typed. The results showed that in most cases only one REA-type is present. In the 13 families investigated in 4 of the 26 children (15%) and in 1 of the 13 spouses (8%) of the adult periodontitis patients an indistinguishable REA-type was found within the families. This suggests that also in the case of adult periodontitis transmission of A. actinomycetemcomitans is possible, but does not seem to occur easily.