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  • Each year, there are ∼300 dog and cat bites per 100,000 population in the United States, with most bites inflicted by pet animals.

  • The microflora of bite wounds typically reflects the oral flora of the biting animal.

  • Bites from many different animals can transmit rabies and tularemia.


  • Epidemiology: Dogs bite ≥4.7 million people per year, causing 80% of all animal bites; 15–20% of dog bites become infected.

  • Bacteriology: includes aerobic and anaerobic organisms, such as β-hemolytic streptococci; Eikenella corrodens; Capnocytophaga canimorsus; and Pasteurella, Staphylococcus, Actinomyces, and Fusobacterium species

  • Clinical Features: typically manifest within 8–24 h after the bite as local cellulitis with purulent, sometimes foul-smelling discharge. Systemic spread (e.g., bacteremia, endocarditis, brain abscess) can occur. C. canimorsus infection can present as sepsis syndrome, DIC, and renal failure, particularly in pts who are splenectomized, have hepatic dysfunction, or are otherwise immunosuppressed.


  • Epidemiology: Cat bites and scratches result in infection in >50% of cases.

  • Bacteriology: includes organisms similar to those involved in dog bites. Pasteurella multocida and Bartonella henselae, the agent of cat-scratch disease, are important cat-associated pathogens.

  • Clinical Features: P. multocida infections can cause rapidly advancing inflammation and purulent discharge within a few hours after the bite. Dissemination (e.g., bacteremia, pneumonia) may occur. Because of deep tissue penetration by narrow, sharp feline incisors, cat bites are more likely than dog bites to cause septic arthritis or osteomyelitis.


  • Old World monkeys (Macaca species): Bites may transmit herpes B virus (Herpesvirus simiae), which can cause CNS infections with high mortality rates.

  • Seals, walruses, polar bears: Bites may cause a chronic suppurative infection known as seal finger, which is probably due to Mycoplasma species.

  • Small rodents (and their predators): Bites may transmit rat-bite fever, caused by Streptobacillus moniliformis (in the United States) or Spirillum minor (in Asia).

    • – Rat-bite fever occurs after the initial wound has healed, a feature distinguishing it from an acute bite-wound infection.

  • S. moniliformis infections manifest 3–10 days after the bite as fever, chills, myalgias, headache, and severe migratory arthralgias followed by a maculopapular rash involving the palms and soles. Disease can progress to metastatic abscesses, endocarditis, meningitis, and pneumonia.

    • – Haverhill fever is an S. moniliformis infection acquired from contaminated milk or drinking water and has manifestations similar to those described above.

      • S. minor infections cause local pain, purple swelling at the bite site, and associated lymphangitis and regional lymphadenopathy 1–4 weeks after the bite, with evolution into a nonspecific systemic illness.


  • Epidemiology: Human bites become infected 10–15% of the time.M

    • Occlusional injuries are inflicted by actual biting; clenched-fist injuries result when the fist of one individual strikes the teeth of another and are particularly prone to serious infection.

    • – Clenched-fist injuries are more common and typically result ...

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