Household Cluster of Salmonella Infection Associated with a Pet Bearded Dragon in Japan: cgMLST-Based Source Attribution and Gaps in Recognition

Reptile-associated salmonellosis has been reported only sporadically in Japan. In routine clinical and public health practice, reptile exposure histories may not always be elicited, and human and animal Salmonella isolates are not routinely linked for source attribution. Two siblings in a household that kept a bearded dragon developed salmonellosis during the same period. Because exposure to the pet reptile was suspected, isolates from the patients and the household bearded dragon were compared by core-genome multilocus sequence typing (cgMLST). The initial isolates from both siblings and the bearded dragon were indistinguishable by cgMLST, providing strong molecular support for a household cluster associated with exposure to the pet reptile. In contrast, the isolate obtained from the elder sibling at follow-up differed from the initial isolates, suggesting that reptiles may carry multiple Salmonella strains and that repeated household exposure may occur. This case suggests that RAS may be underrecognized when animal exposure histories are not obtained and human and animal isolates are not compared. Animal contact histories should be assessed in addition to dietary histories, and molecular comparison of human and animal isolates should be considered when reptile-associated transmission is suspected.