What antibiotic should be used for a dog bite after failure of Augmentin (amoxicillin-clavulanate) and should a repeat X-ray (XR) be done?

Antibiotic Treatment After Augmentin Failure for Dog Bites and Need for Repeat X-ray

For dog bite infections that have failed Augmentin therapy, switch to doxycycline as the preferred alternative oral agent, or consider intravenous options such as ampicillin-sulbactam, piperacillin-tazobactam, or a second-generation cephalosporin like cefoxitin if the infection is severe; a repeat X-ray should be performed if there is pain disproportionate to the injury near a bone or joint to evaluate for bone involvement. 1

Alternative Antibiotic Options After Augmentin Failure

Oral Options:

• Doxycycline is the recommended first alternative for patients with Augmentin failure 1
• Fluoroquinolones (ciprofloxacin, levofloxacin, moxifloxacin) plus metronidazole for anaerobic coverage 1
• Trimethoprim-sulfamethoxazole plus metronidazole or clindamycin (to ensure anaerobic coverage) 1

Intravenous Options (for severe infections):

• Beta-lactam/beta-lactamase combinations such as ampicillin-sulbactam or piperacillin-tazobactam 1
• Second-generation cephalosporins such as cefoxitin 1
• Carbapenems (ertapenem, imipenem, meropenem) for severe infections 1

Microbiology Considerations

• Dog bite wounds typically contain mixed aerobic and anaerobic bacteria 1
• Pasteurella species are found in 50% of dog bite wounds 1, 2
• Staphylococci and streptococci are present in approximately 40% of dog bites 1, 3
• Capnocytophaga canimorsus, though rare, can cause serious bacteremia, especially in immunocompromised patients 1, 4

When to Obtain Repeat X-rays

• Repeat X-ray is strongly indicated if there is pain disproportionate to the injury near a bone or joint 1
• X-ray should be performed if there is:
  • Suspicion of bone involvement or periosteal penetration 1
  • Limited range of motion in adjacent joints 2
  • Progressive swelling despite appropriate antibiotic therapy 1
  • Persistent pain after 48-72 hours of appropriate treatment 2

Management of Complications

• Infectious complications requiring imaging include:
  • Septic arthritis (3-4 week treatment course) 1
  • Osteomyelitis (4-6 week treatment course) 1
  • Subcutaneous abscess formation 1
  • Tendonitis 1

Additional Management Considerations

• Wounds should be re-evaluated, thoroughly cleaned, and irrigated with sterile normal saline 1
• Deeper debridement may be necessary if the infection is progressing 1
• Elevation of the injured body part, especially if swollen, accelerates healing 1
• Close follow-up within 24 hours is recommended for outpatients 1
• Consider hospitalization if infection progresses despite appropriate antimicrobial therapy 1

Common Pitfalls to Avoid

• Avoid first-generation cephalosporins (e.g., cephalexin), penicillinase-resistant penicillins (e.g., dicloxacillin), macrolides (e.g., erythromycin), and clindamycin alone as they have poor activity against Pasteurella multocida 1, 3
• Do not close infected wounds 1
• Do not miss evaluating for potential bone or joint involvement, which would require prolonged antibiotic therapy 1
• Do not forget to consider rabies prophylaxis, especially if the dog's vaccination status is unknown 2