Transmission of C difficile Between People and Pets Appears Rare

Clostridioides difficile transmission between pet owners and their pets is uncommon, according to a study that tested for genetically related C difficile strains published in Zoonoses and Public Health.

“While pets did sometimes carry C difficile, there was only one of 47 households where the pet and owner harbored genetically identical isolates,” wrote corresponding author Laurel E. Redding, VMD, PhD, of the University of Pennsylvania School of Veterinary Medicine, Kennett Square, Pennsylvania, and study coauthors. “Moreover, the dog in question in that household had recently received antimicrobial therapy itself, which may have resulted in gut dysbiosis and predisposition to C difficile colonization/infection.”

The study included 59 pet owners with diarrhea. Researchers obtained fecal samples from the patients, as well as fecal samples from their total 72 dogs and nine cats, and tested for C difficile. Microorganisms in pet owners and their animals with the same toxin profile or ribotype, isolates underwent genomic sequencing.

C difficile was detected in 30 humans, 10 dogs, and no cats, according to the study. However, in just two of the study’s 47 households was C difficile detected in both human and pet. In one of them, the C difficile isolates had different toxin profiles or ribotypes.

In the other, the pet and owner harbored genetically identical isolates. The dog had recently undergone an antibiotic course of cefpodoxime and metronidazole.

In contrast to human-to-human transmission, inter-species transmission rarely occurs, the study suggests.

“It is unclear why pets appear to only infrequently acquire C difficile from their owners,” researchers wrote. “It may be that the canine gut microbiota is better able to provide colonization resistance against C difficile, even when in an environment where C difficile is present, because of canine behaviors that result in frequent acquisition of diverse microflora.”

Reference

Redding LE, Habing GG, Tu V, et al. Infrequent intrahousehold transmission of Clostridioides difficile between pet owners and their pets. Zoonoses Public Health. 2023;70(4):341-351. doi: 10.1111/zph.13032