I’m not a big fan of the title of a paper in the latest edition of the Canadian Journal of Infectious Diseases and Medical Microbiology…”Pets are ‘risky business’ for patients undergoing continuous ambulatory peritoneal dialysis” (Yahya et al 2013), even though it’s an interesting paper that actually takes a reasonable approach to zoonotic disease risk from pets. I get a little concerned with titles like this that might reinforce certain excessive fears that some physicians have (usually from lack of understanding) regarding pets and zoonoses.
The paper is a case report of a 49-year-old man with kidney failure who was undergoing peritoneal dialysis at home. Peritoneal dialysis involves infusing fluid into the abdomen and then draining it, to help flush toxins out of the body. This requires an indwelling abdominal catheter that is placed through a small hole in the body wall. Any time a tube gets stuck into the body, there’s some risk of it acting as a pathway for infectious organisms to also get in. Good management practices are essential to reduce the risk of infection in these cases, but good practices are not always used.
In this case, the person had a dog and a cat in the household. Over the course of about eight months, the man developed four different infections. One was caused by Pasteurella multocida, a bacterium that is very common in the mouths of cats. Another was caused by Enterobacter cloacae, a bacterium that is found in the intestinal tract of a variety of species, so it may or may not have been a pet-associated infection. The last two were both Capnocytophaga infections. This bacterium is ubiquitous in the mouths of dogs, and to a lesser extent cats.
How did these bacteria cause the infections?
The patient was adamant that the pets didn’t have contact with the dialysis tubing and that they were not present when he performed dialysis. However, he admitted that his hand hygiene practices weren’t always great, so presumably he contaminated his dialysis tubing with bacteria on his hands that came from the pets (either directly or from contaminated household surfaces).
Did the infections really come from the pets?
There was no testing of the pets to confirm it, but Pasteurella multocida and Capnocytophaga canimorsus are clearly pet-associated bugs, so I don’t have much doubt that pets were the source.
So, are pets risky in situations like this?
Yes, but so are lots of things. The key is whether we can effectively manage the risk.
Does the presence of pets in the house increase the risk of a person undergoing peritoneal dialysis getting an infection?
We don’t know. I’m not aware of anyone looking at this specifically. However, since people are still able to publish single case reports of pet-associated infections, it’s fair to assume that pet-associated infections in these patients are relatively rare (and therefore make interesting case reports).
Should people undergoing peritoneal dialysis at home get rid of their pets?
I can’t support that (unless no onein the household really has any affection for the pet, in which case why not eliminate the risk by finding it a new home). Infections seem to be rare and basic practices (especially good hand hygiene) can presumably reduce the risk even further.
The authors conclude with some nice, balanced recommendations. “Our data support the recommendations by Rondon-Berrios and Trevejo-Nunez (2), Weiss and Panesar (12), Pers et al (10), Schiller et al (6) and Sol et al (3) that PD patients who own pets be made aware of the need for proper hand hygiene before PD bag changes and the risk of zoonotic infection if these precautions are not taken. The need to ensure pet oral secretions do not come into contact with PD equipment and the threat of these infections should be clearly communicated to PD patients. We recommend strict hygiene guidelines be emphasized and periodically reviewed with PD patients who have pets.”