Possible transmittance of A. actinomycetemcomitans from a dog to a child with rapidly destructive periodontitis

This study was designed to detect a possible exogenous source of oral A. actinomycetemcomitans in a family where the 2 children suffered from Papillon‐Lefévre syndrome (PLS). Every month for 1 yr subgingival dental plaque samples were obtained from the 2 children, their parents, grandparents and their pet dog. Dental plaque samples were also obtained from a 12‐yr‐old boy whose family had owned a dog from the same litter as the PLS family. Dispersed and diluted plaque samples were cultured anaerobically on Slots medium and A. actinomycetemcomitans was identified by standard criteria. The various A. actinomycetemcomitans wild strains were mass cultivated and their total genomes compared after DNA restriction endonuclease mapping in 2 different electrophoretic gels, using ECO RI, HIND III and BAM HI. Only the plaque samples from 1 of the PLS children, the pet dog and the 12‐yr‐old boy produced A. actinomycetemcomitans. The restriction endonucleases could not distinguish between the A. actinomycetemcomitans wild strains from the PLS child and those from the family dog or the 12‐yr‐old boy. However, the methods could readily differentiate between both reference strains and wild strains, indicating that transfer of A. actinomycetemcomitans from dog to the PLS child had taken place.