Peritoneal dialysis infections and pets
Pasteurella multocida is a bacterium that is commonly found in various pet species. It typically inhabits the upper respiratory tract of healthy pets, although it is an important cause of respiratory disease in rabbits ("snuffles"). It is also a zoonotic pathogen, and human infections are sporadically reported. Most are associated with bites, mainly from cats. Others have involved pets licking wounds or broken skin. Infections seem to be a particular concern in people undergoing dialysis because of kidney failure. Infections have been associated with things like cats chewing on dialysis tubing and pets having contact with catheter sites.
A recent report described another dialysis-associated infection in person with chronic kidney disease and diabetes (Satomura et al 2010, Ther Apher Dial). The person developed peritoneal dialysis-associated peritonitis. Peritonitis is infection of the internal lining of the abdominal cavity (the space between the intestines/other abdominal organs and the body wall). For peritoneal dialysis, a catheter is left in place which passes through the body wall, and infections can occur from bacteria migrating through or along the catheter and into the peritoneal cavity. In this case, Pasteurella multocida was isolated from the infected peritoneal fluid. The source of infection wasn’t clear, and no obvious risk factors like a cat gnawing on the catheter were reported. However, the same bacterium was isolated from a throat swab taken from the person’s cat. Given how common this bacterium is in cats, how uncommon it is in people, and previous reports of cat-associated infection, it’s logical to assume that the cat was the source.
The fact that no clear risk factors were identified in this case highlights the ever-present (but still relatively low) risk to people with dialysis catheters who have contact with cats. Certain things like keeping the cat away from the catheter site and other dialysis items are common sense and presumably very important. However, general hygiene measures are also probably very important. It is logical that a cat owner could frequently get this bacterium on his or her hands from regular interaction with the cat, or potential from contact with objects like food and water bowls. Good attention to hand hygiene, especially before touching the catheter or any dialysis items, must not be overlooked, and should be an important part of counseling of dialysis patients who own pets. Unfortunately, the risks associated with pets are not always discussed by physicians (who may not even ask about pet ownership), so some people don’t get the required information.
Note: Image is from http://www.kidney.org.uk/kids/crf/page09.html. It's presumably meant to be a cute image showing a happy (and otherwise healthy) kid undergoing dialysis. It's interesting that they show a cat in the picture, but no where on the page is there any mention about infection control measures that should be taken around pets. It seems like a missed education opportunity to me.
Peritoneal dialysis and pets
Peritoneal dialysis is used to treat some people with chronic kidney failure. Infection is a major concern, particularly peritonitis (infection of the lining of the abdomen) because peritoneal dialysis involves having an indwelling catheter that goes through the skin and body wall directly into the abdominal cavity.
Infections can occur from bacteria that inadvertently get flushed into the abdomen during dialysis treatment or potentially migrate along the side of the catheter. Accordingly, most infections associated with peritoneal dialysis are caused by bacteria that are found on peoples' skin, such as Staphylococcus aureus.
While the vast majority of peritoneal dialysis infections are human-associated, infections from pets have been reported. Multiple different pet species have been implicated, even hamsters - one case report described an infection in a child that was thought to be caused by a hamster that slept in the same bed as the child (Campos et al 2000).
A recent study in the journal Seminars in Dialysis (Broughton et al 2010) involved a review of the scientific literature for reports of pet-associated peritoneal dialysis infections, as well as a review of records from the authors' peritoneal dialysis unit.
In their review, they identified 124 reported infections caused by zoonotic microorganisms in the literature, involving 12 different microorganisms. The most common microorganisms were Campylobacter, Pasteurella, Zygomycetes, Neisseria, Rhodococcus, Listeria, Mycobacterium avium complex, Capnocytophaga spp, Salmonella, Brucella and Bordetella bronchiseptica. However, only a subset of these were probably associated with pet contact, and retrospectively determining the sources is quite difficult for some. For example, Campylobacter and Salmonella could as easily (or more easily) come from contact with raw meat as from pets. Infections were fatal in 13.5% of cases, demonstrating why this is an important issue.
The most common bacterium causing convincing pet-associated infections was Pasteurella, which can be found in the mouths (and other places) of healthy pets. It is a common cause of pet bite infections and it makes sense that Pasteurella could contaminate pet owners' hands or the dialysis catheter site. In the study of their own hospital's cases, the authors found similar findings, with a low rate of zoonotic infections and a predominance of Pasteurella among those.
Literature reviews aren't a great way of determining the true scope of a problem, because they require people to:
- identify the infection
- identify a pet as a possible source (often the weak link; furthermore, identifying an infection caused by a potentially zoonotic microorganism doesn't necessarily mean a pet was the source)
- decide to write a case report
- get that case report accepted by a journal
Studying medical records has limitations as well, since steps 1 and 2 still need to be performed (with the weak link again being thinking about a pet-association). So, care should be taken when interpreting the results of this study. However, while the results indicate that pet-associated peritoneal dialysis infections do occur, they are probably relatively uncommon.
While pet-associated infections are likely uncommon, any peritoneal infection can be a major problem, so common sense measures that would likely reduce the risk should be used:
- Avoid contact of pets with the dialysis catheter and catheter site
- Wash hands after having any contact with pets
- Don't let pets sleep in the bed
- Wash hands before touching the catheter
Additionally,
- Physicians should be aware of the potential for pet-associated infections, and pet contact by their patients
- If a pet (usually a cat) bites the tubing, this should be reported to a physician ASAP and preventative treatment for infection might be indicated
- Initial antibiotic therapy choices should cover common pet-associated pathogens if there is a history of contact of pets with the catheter or tubing.
People with peritoneal dialysis catheters shouldn't fear their pets, and there is no need for these people to get rid of pets (although they should avoid high-risk pets like reptiles). Pet owners are presumably at somewhat higher risk than non-pet-owners, but the risk appears to be fairly low. In most situations, the positive aspects of pet ownership probably outweigh the risks.
Image: Schematic diagram of peritoneal dialysis (click image for source)
