If a hand laceration accompanies a suspected fight bite, which organism is commonly implicated requiring antibiotics?

• A. Staphylococcus aureus
• B. Streptococcus pyogenes
• C. Pseudomonas aeruginosa
• D. Eikenella corrodens

Answer: (D)

Injury from a human bite, especially a fight bite, brings bacteria from the mouth into the wound. The organism most classically implicated is Eikenella corrodens, a gram-negative rod that resides in oral flora. In these hand wounds, infections are often polymicrobial and include anaerobes, so antibiotics picked should cover oral flora, including Eikenella. That’s why regimens like amoxicillin-clavulanate or ampicillin-sulbactam are commonly used—they target Eikenella plus the anaerobes typically involved. While Staphylococcus aureus and Streptococcus species can contribute to wound infection, they aren’t the hallmark pathogen of human bite injuries, and Pseudomonas is more associated with other contexts such as puncture wounds through footwear. The key idea is that Eikenella corrodens is the organism most commonly implicated in fight bites requiring antibiotic therapy.