Hip replacementThe Canadian Journal of Infectious Diseases and Medical Microbiology has been good, recently, for a zoonotic disease article or two. The latest edition has a report of Pasteurella multocida infections of prosthetic joints (Lam et al. 2015). Pasteurella multocida is a bacterium that’s commonly found in the mouths of dogs and cats, and can cause infections in those species, as well as people, if given the right opportunity. That usually occurs after a bite, but can also occur in other situations, particularly when animal saliva is involved (e.g. licking).

The report describes a complicated case in which a women had a hip replaced, then developed a series of infections of the surgical implant over the following 8 years. These were caused by a variety of different bacteria.  As is often the case, the decision was made to remove the implant because elimination of infections on foreign materials in the body can be very difficult. She underwent a surgery to remove the artificial hip, then was put on a course of antibiotics prior to a planned surgery to put in a new hip. It was during this in-between period that the latest infection developed, and she was taken to surgery to clean up the infected site. Samples collected during surgery yielded Pasteurella multocida, which lead to some questions about animal contact (better late than never?). She lived with 5 dogs and 2 cats, and the dogs had been allowed to lick a wound on her leg. Fortunately, she was treated successfully and got her new hip a couple of months later.

As part of the case report, the authors reviewed the literature and found 32 published cases of P. multocida prosthetic joint infections. That doesn’t mean there have only been 32 infections ever – presumably many more have occurred and not been published. So, it’s a rare issue but it does occur. Some of the highlights of their review:

  • 22 cases involved cats while 10 involved dogs.
  • 26/32 were in women.
  • Old age and a few things associated with compromised immune systems were commonly present.
  • Most cases occurred months to years after surgery but shortly (days to weeks) after animal contact. That’s probably a bit of a dodgy statement though, since rarely do people have just one defined animal contact. If someone has a dog, they probably have contact with the dog most days – if they develop an infection after surgery it would be impossible to discern which contact on what day actually led to infection. Their last contact might have been days to weeks before the onset of disease, but that doesn’t mean that’s when they were infected.

Some practical concluding statements in the paper were:

It is important for clinicians to ask about animal exposure when evaluating a patient with a PJI, particularly if the infection has occurred remote from the surgery [i.e. the infection developed a long time from of surgery], so that the appropriate empirical therapy can be chosen. … In light of the case presented here, it is reasonable to counsel patients about the risk for zoonotic infections of surgical wounds and the steps that can be taken to potentially reduce this risk, such as maintaining good hand hygiene after pet contact, keeping wounds covered, avoiding direct pet contact with any unhealed, uncovered or open wounds, and reporting all significant animal-induced wounds to a physician.”

On a (somewhat) related note, a boy from Idaho was recently diagnosed with meningitis caused by P. multocida. The poorly written news article doesn’t provide much information or anything about animal contact, but I have to assume there was an animal source.