Comparison of periodontal pathogens between cats and their owners

The periodontal pathogens Porphyromonas gingivalis and Tannerella forsythia are strongly associated with periodontal disease and are highly prevalent in humans with periodontitis. Porphyromonas and Tannerella spp. have also been isolated from the oral cavity of cats. The oral microflora in animals was compared with those in humans in earlier studies, but no studies are available on the comparison of the oral microflora from pets and their respective owners. The aim of this study was to determine the presence of these bacteria in the oral microflora of cats and their owners, since animal to human transmission, or vice versa, of oral pathogens could have public health implications. This study investigated the prevalence of Porphyromonas gulae, P. gingivalis, and T. forsythia in the oral microflora of cats and their owners, using culture and polymerase chain reaction (PCR). All Porphyromonas isolates from cats (n=64) were catalase positive, whereas the Porphyromonas isolates from owners (n=7) were catalase negative, suggesting that the isolates from cats were P. gulae whereas those from the owners were P. gingivalis. T. forsythia was recovered from both cats (n=63) and owners (n=31); the proportion of T. forsythia relative to the total CFU was higher in cats with periodontitis than in cats without periodontal disease. Genotyping of T. forsythia isolates (n=54) in six cat/owner couples showed that in one cat/owner couple the T. forsythia isolates (n=6) were identical. These T. forsythia isolates were all catalase positive, which led us to hypothesize that transmission from cats to owners had occurred and that cats may be a reservoir of T. forsythia.