Animal bites.

Animal bites are an extremely common problem in the United States. Dogs are by far the most common offender, closely followed by cats, humans, and rats. Most injuries are trivial, but can become infected, and fatalities do occur. A wide variety of organisms cause a multitude of clinical problems, but cellulitis and lymphangitis caused by Pasteurella multocida are most common. Human bites, especially of the hand, present major problems in management, and staphylococci or streptococci are frequent pathogens. Penicillin is an effective first-line antibiotic for animal bites, while a penicillinase-resistant penicillin, a cephalosporin, or erythromycin should be used for human bites. Attention should always be paid to the potential problems of rabies and tetanus.