Cat bite infections (and dumb headlines)

It's a scary sounding headline: “Cat Bites Pose Risk Of Infection As 1 In 3 Patients Bitten Hospitalized; Teeth Inject Bacteria Into Joints, Tissue” and it cites a research article from the Mayo Clinic in the Journal of Hand Surgery (Babovic et al 2014).

Cat bites are nasty. The mouth of any cat harbours thousands of different bacteria and their needle-like teeth can inoculate bacteria deep into tissues. A variety of complications can occur after cat bites, and they are not something to dismiss as innocuous.

But hospitalization of 1/3 of people that are bitten? Not a chance.

Let’s see what the paper actually said:

The paper is entitled “Cat bite infections of the hand: assessment of morbidity and predictors of severe infection.” It was a review of 193 patients that were presented to one hospital with cat bite injuries to the hand.

  • Point 1: The study population is people who went to the hospital for a cat bite, not all people who were bitten.
  • Point 2: The study only looked at people bitten on the hand(s). That’s a common site to be bitten by a cat, but it’s also a high-risk site for complications because hands have lots of sensitive  and fairly superficial structures (e.g. bones, joints, tendon sheaths, nerves) that are more likely to cause problems if they get infected.

So, it’s pretty clear that 1/3 of all bites don’t result in hospitalization. In reality it's a much smaller percentage, but you really don’t want to be part of that small group, so bite avoidance and proper post-bite first aid are still very important.

Some other highlights from the paper:

  • Nineteen percent (19%) of patients were admitted to the hospital at presentation (i.e. they had to stay at least one night). A further 11% failed initial outpatient antibiotic treatment and were subsequently hospitalized.
  • Sixty-nine percent (69%) of patients were women (not sure why - could be that more women own cats, more women get bitten by their cats, or more women are likely to seek medical care if they're bitten by a cat, or a number of other reasons).
  • Risk factors for hospitalization (compared to people that presented to the hospital for a bite but did not require hospitalization) included smoking, having a compromised immune system and a bit over a tendon sheath or joint. Those are not surprising at all.
  • Signs of inflammation (e.g. redness, swelling at the site of the bite) were associated with increased risk of hospitalization. Not too surprising either.
  • The average time from bite to presentation was 27 hours. Interestingly, time from the bite to presentation was not a risk factor for complications, as this has been reported as a risk factor previously (and it makes sense that it would be). However, don’t take that as an indication that you can wait a long time to seek medical care after a high-risk bite.
  • Complications were those that are typically encountered with cat bites (and good reasons to avoid them): abscesses, tendon infection and nerve involvement.
  • Seven percent (7%) of all patients (not just the hospitalized ones) had loss of joint mobility after resolution of infection. Remember that cat bites can have long-term consequences.
  • Cultures were only available for some patients, but Pasteurella multocida was the most commonly isolated bacterium. This bacterium is a notorious bite-associated bacterium and is commonly (if not always) found in the mouths of cats.

Crappy headline but an important topic.

Cat bites are bad, and it doesn’t matter if the hospitalization rate is 30% or 0.3%, they can still result in serious problems. They can also be largely avoided through proper cat handling, understanding some basic cat behaviour and proper first aid - things every cat owner should know.

More information about cats and about cat bites can be found on the Worms & Germs Resources - Pets page.

Photo credit: Moyogo (click image for source)

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Comments (1) Read through and enter the discussion with the form at the end
holly vandecar - February 26, 2014 12:58 PM

My cat bit me a year ago (he is 12 years old). I never felt such pain in my right hand. I went to the ER & was immediately admitted to the hospital for 2 days. A cat bite has more bacteria than most other animals. I would tell everyone to be careful around cats. If you do experience a cat bite, go immediately to an ER!!!

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