What is the recommended prophylactic intravenous (IV) antibiotic for dog bites?

Prophylactic IV Antibiotic for Dog Bites

For patients requiring intravenous prophylactic antibiotics for dog bites, ampicillin-sulbactam is the recommended first-line agent, providing comprehensive coverage against the polymicrobial flora including Pasteurella species, staphylococci, streptococci, and anaerobes commonly found in these wounds. 1

IV Antibiotic Options

The Infectious Diseases Society of America guidelines specify several intravenous options for dog bite wounds 1:

• Ampicillin-sulbactam is the preferred beta-lactam/beta-lactamase inhibitor combination 1
• Piperacillin-tazobactam provides broader spectrum coverage 1
• Second-generation cephalosporins (such as cefoxitin) offer adequate polymicrobial coverage 1
• Carbapenems (ertapenem, imipenem, or meropenem) are reserved for more severe infections or resistant organisms 1

When IV Antibiotics Are Indicated

Intravenous prophylaxis should be considered in specific high-risk scenarios 1, 2:

• Severe or deep bite wounds with significant tissue damage 1
• Wounds requiring hospitalization due to extent or location 1
• Immunocompromised patients or those with asplenia 1
• Patients with advanced liver disease (at risk for Capnocytophaga canimorsus sepsis) 1
• Wounds with bone, joint, or tendon penetration 1, 2
• Hand wounds that are moderate to severe 2, 3

Microbiology Considerations

Dog bite wounds are polymicrobial, yielding an average of 5 bacterial species 1:

• Pasteurella species are isolated from 50% of dog bites 1
• Staphylococci and streptococci are found in approximately 40% of cases 1
• Anaerobes (Bacteroides, Fusobacterium, Porphyromonas, Prevotella) are present in 50% of dog bites 1, 4
• Capnocytophaga canimorsus can cause fatal sepsis, especially in asplenic or cirrhotic patients 1

Transition to Oral Therapy

Once the patient stabilizes and can tolerate oral medications, transition to amoxicillin-clavulanate is recommended 1, 5:

• Prophylactic duration: 3-5 days for high-risk patients 5
• Established infection duration: 7-14 days depending on severity 5
• Amoxicillin-clavulanate provides complete coverage for both aerobic and anaerobic bacteria without requiring additional metronidazole 5

Critical Pitfalls to Avoid

Do not use these antibiotics as they have poor activity against Pasteurella multocida 1:

• First-generation cephalosporins (cephalexin)
• Penicillinase-resistant penicillins (dicloxacillin) as monotherapy
• Macrolides (erythromycin)
• Clindamycin as monotherapy

Adjunctive Measures

Beyond antibiotics, essential management includes 1:

• Wound irrigation with copious sterile normal saline 1
• Elevation of the injured extremity to reduce swelling 1
• Avoid primary closure of infected wounds 1
• Tetanus and rabies prophylaxis as indicated 2
• Follow-up within 24 hours for outpatients 1