What is the antibiotic of choice and dose for a dog bite to the hand with bone exposure?

Dog Bite to Hand with Bone Exposure: Antibiotic Management

For a dog bite to the hand with bone exposure, initiate intravenous ampicillin-sulbactam 1.5-3.0 g every 6-8 hours immediately, as this represents a high-risk wound requiring hospitalization and IV therapy due to bone penetration. 1, 2

Why IV Therapy is Mandatory

• Bone exposure mandates intravenous antibiotics because penetration of bone, joint, or tendon requires aggressive treatment to prevent osteomyelitis and septic arthritis 2
• Hand wounds are inherently more serious than wounds to other body parts due to complex anatomy and higher complication rates 1
• Pain disproportionate to injury near bone or joint suggests periosteal penetration and necessitates prolonged therapy 1

First-Line IV Antibiotic Choice

Ampicillin-sulbactam is the recommended first-line IV agent because it provides comprehensive coverage against the polymicrobial flora typical of dog bites 1, 2:

• Covers Pasteurella multocida (present in 50% of dog bites) 2
• Covers staphylococci and streptococci (present in ~40% of cases) 2
• Covers anaerobes including Bacteroides, Fusobacterium, Porphyromonas, and Prevotella (present in 50% of dog bites) 1, 2

Alternative IV Options

If ampicillin-sulbactam is unavailable or contraindicated 1, 2:

• Piperacillin-tazobactam 3.37 g every 6-8 hours (broader spectrum coverage)
• Cefoxitin 1 g every 6-8 hours (second-generation cephalosporin with adequate polymicrobial coverage)
• Carbapenems (ertapenem 1 g daily, imipenem 1 g every 6-8 hours, or meropenem 1 g every 8 hours) reserved for severe infections or resistant organisms

Critical Management Pitfalls to Avoid

Do NOT use these antibiotics as they miss Pasteurella multocida 1:

• First-generation cephalosporins (cephalexin, cefazolin)
• Penicillinase-resistant penicillins (dicloxacillin alone)
• Macrolides (erythromycin)
• Clindamycin alone

Duration of Therapy

• Osteomyelitis requires 4-6 weeks of treatment if bone infection develops 1
• Septic arthritis requires 3-4 weeks if joint involvement occurs 1
• Initial IV therapy should continue until clinical improvement, then transition to oral therapy 2

Transition to Oral Therapy

Once stabilized, transition to amoxicillin-clavulanate 500-875 mg twice daily 1, 2:

• This provides complete aerobic and anaerobic coverage without requiring additional metronidazole 2
• Continue for total treatment duration of 7-14 days depending on severity 2

Essential Adjunctive Measures

• Copious irrigation with sterile normal saline (no iodine or antibiotic solutions needed) 1, 2
• Do NOT close infected wounds - this is a critical error that worsens outcomes 1
• Elevate the hand using a sling to reduce swelling and accelerate healing 1, 2
• Surgical debridement and exploration to assess extent of bone, tendon, or joint involvement 1
• Follow-up within 24 hours is mandatory 1, 2

Additional Prophylaxis Requirements

• Update tetanus prophylaxis (0.5 mL intramuscularly if outdated or unknown status) 1
• Consider rabies prophylaxis - consult local health department about need for rabies immunoglobulin and human diploid cell vaccination 1

High-Risk Patient Considerations

Patients with these conditions require particularly aggressive IV therapy 2:

• Immunocompromised status
• Asplenia (risk of Capnocytophaga canimorsus fatal sepsis)
• Advanced liver disease (risk of Capnocytophaga sepsis)