summary Human Bite wounds are associated with infections of the hand due to presence of various aerobic and anerobic pathogens. Diagnosis is made by history and presence of open wounds most commonly over the dorsal aspect of the 3rd or 4th MCP joint. Treatment is generally surgical debridement and antibiotics (must protect against aerobic and anaerobic bacteria). Epidemiology Incidence human bite wounds to the hand consist of approximately 2% of bite wounds third most common bite behind dog and cat Demographics more common in males Location typically dorsal aspect of 3rd or 4th MCP joint "fight bite" Etiology Pathophyiology mechanism most often result of direct clenched-fist trauma (from tooth) after punching another individual in the mouth can also result from direct bite (i.e. child biting another child) pathoanatomy tooth penetrates capsule of MCP joint flora (bacteria) from mouth enter joint bacteria become trapped within joint as fist is released from clenched position bacteria now caught under extensor tendon and/or capsule microbiology typically polymicrobial most common organisms alpha-hemolytic streptococcus (S. viridans) and staphylococcus aureus eikonella corrodens in 7-29% other gram negative organisms Associated conditions extensor tendon lacerations can be missed due to proximal tendon retraction Presentation History direct clenched-fist trauma to another individual's mouth often overlooked must have high index of suspicion as patients often unwilling to reveal history consider the injury a "fight-bite" until proven otherwise possible delay in presentation until symptoms become intolerable Symptoms progressive development of pain, swelling, erythema, and drainage over wound Physical exam fight bite small wound over dorsal aspect of MCP joint wound often transverse, irregular typically 3rd and/or 4th MCPs, but can involve any digit erythema, warmth, and/or edema overlying wound and joint ± purulent drainage must assess for integrity of extensor tendon function possible pain with passive ROM of MCP joint typically no involvement of volar/flexor surface of digit neurovascular status typically preserved Imaging Radiographs indicated to assess for foreign body (i.e. tooth fragment) and for fracture Studies Culture not routinely obtained in ED due to contamination deep culture obtained in OR aerobic and anaerobic Diagnosis Clinical diagnosis is made with careful history and physical examination Treatment Operative I&D, IV antibiotics indications fight bite joints or tendon shealths are involved antibiotics IV antibiotics directed at Staph, Strep, and gram-negative organisms ampicillin/sulbactam (unasyn) PO antibiotics upon discharge for 5 to 7 days amoxicillin/clavulanic acid (augmentin) debridement debridement of wound and joint capsule wound left open for drainage obtain gram stain and culture