Know high-risk bites for infection
September 1, 1998
Know high-risk bites for infection
Although all animal bites are at risk for infection, certain types of bites are at higher risk. "Human bites and cat, monkey, and other wild animal bites are high risk because of the shape of the tooth (cats), the area bitten (the hand in humans), and the mouth flora (wild animals)," says Edward Otten, MD, professor of emergency medicine at the University of Cincinnati and president of the Wilderness Medical Society, based in Indianapolis. Here are some bites at high risk for infection with tips for each:
Human bites. "Human bites are notorious for wound infections and cellulitis, and they are commonly missed," says Timothy Erickson, MD, FACEP, director for the emergency medicine residency program and division of clinical toxicology at the University of Illinois at Chicago Medical Center. "They frequently occur on the hand, from patients punching their foes in the mouth and catching the victimtooth on their knuckle." These always require antibiotic therapy and, usually, hospital admission for intravenous antibiotic therapy, he notes.
Human bites should not be closed or sutured. "Always leave them open, " says Otten. "The incidence of infection really goes up when you close a human bite, because you are sealing in all the bacteria and the wound can't drain."
It's possible that patients may deny that a bite is human, due to embarrassment over a domestic dispute. "If you look at the hand in a fist and the cut is over their knuckles, we consider that high risk for a human bite," says Otten. "They may say, 'I didn't really hit him-I missed and hit the door.' Well, maybe it did and didn't. With human bites, you always want to err on the side of caution."
Bites to hand. Bites to hand are at higher risk for infection and are usually treated with antibiotics. "When the animal's tooth goes through a tendon and the patient moves their hands, the tendon slides backward and is contaminated with bacteria," explains Otten. "If you get bit on the leg or the back, there is not as much risk."
Cat bites. Cat bites are more prone to infection than dog bites because of the cylindrical shape of their teeth, notes Erickson. "They usually result in deep tissue puncture wounds with growth of bacterial organisms such as staph, strep, and plasturella. However, dog bites to the extremities commonly result in wound infections if not properly cared for."
Dogs have triangular teeth, which cause a laceration instead of a puncture, notes Otten. "Lacerations are less likely to become infected than puncture wounds, because they are more easily cleaned and debrided," he explains.
Marine bites. "These can usually be cared for by altering the pH of the venom with vinegar (jelly fish stings) or altering the temperature (hot water with lion and cat fish stings)," says Erickson. "Traumatogenic wounds (sharks and barracudas) require more aggressive wound management, tetanus prophylaxis, antibiotic coverage, and evaluation for crush injury and retained foreign bodies."
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