Bites and stings: Clinical

Bites and stings can be caused by a variety of animals, insects, snakes or yes, even humans!

The most common mammalian bites are from dogs, cats, and humans. And each bite transmits the polymicrobial flora that can be found in the mouth - including Staphylococcus aureus, group A Streptococcus species, Klebsiella, Enterococci, Prevotella and many more.

Dog bites can transmit a gram negative rod called Capnocytophaga canimorsus, which can cause gangrene at the bite site and can disseminate and cause sepsis, especially in asplenic individuals and those with liver disease.

Cat bites or scratches - particularly from kittens - can transmit Bartonella henselae, which causes cat scratch disease.

Both dog and cat bites can also transmit Pasteurella multocida which can cause cellulitis at the bite injury.

Finally, human bites can transmit Eikenella corrodens which is a gram negative anaerobe which can cause local and disseminated infection - including being a cause of culture-negative endocarditis - one of the HACEK organisms.

In general, bite wound infections cause local cellulitis and in some cases can lead to a local abscess and fevers.

Dog bites are the most common ones of all, and because dogs have strong jaws they often cause serious tissue injury, but infections aren’t that common.

In contrast, cats have long, thin teeth, that create deep puncture wounds, which very often get infected. Cat bites can even reach the underlying joint space or periosteum, leading to septic arthritis or osteomyelitis.

Like cat bites, human bites also have a high risk of infection.

Most human bites happen due to aggressive play between children, but can also happen among adults.

In a child, if the bite mark is over 2.5 centimeters in diameter, then it’s likely an adult bite, and should raise the suspicion of child abuse.