Cefdinir is NOT Appropriate for Superficial Dog Bite Prophylaxis
Cefdinir should be avoided for dog bite wounds because it lacks adequate coverage against Pasteurella multocida, the pathogen isolated from 50% of dog bites, and first-generation cephalosporins have poor in vitro activity against this critical organism. 1
Recommended First-Line Agent
- Amoxicillin-clavulanate 875/125 mg twice daily is the first-line oral antibiotic for dog bite prophylaxis and treatment, providing comprehensive coverage against Pasteurella species, Staphylococcus, Streptococcus, and anaerobes 1, 2, 3
When to Prescribe Prophylactic Antibiotics (3-5 Days)
Prophylactic antibiotics are indicated for superficial dog bites ONLY if the patient has high-risk features 1, 3:
- Wound location: hand, foot, face, genitals, or near joints 1, 3
- Wound characteristics: puncture wounds, deep wounds, significant tissue damage, or wounds with preexisting/resultant edema 1
- Patient factors: immunocompromised, asplenic, advanced liver disease, diabetes, prosthetic joints, or prosthetic heart valves 1, 3
- Timing: wounds that may have penetrated periosteum or joint capsule 1
For truly superficial, low-risk dog bites (not involving hand/foot/face, no puncture, immunocompetent patient), prophylactic antibiotics provide marginal benefit and may not be necessary 1, 4
Alternative Agents (When Amoxicillin-Clavulanate Cannot Be Used)
For patients without beta-lactam allergy but who cannot take amoxicillin-clavulanate 1, 2:
- Doxycycline 100 mg twice daily (excellent Pasteurella coverage) 1, 2
- Moxifloxacin 400 mg daily (monotherapy with anaerobic coverage) 1
- Penicillin VK 500 mg four times daily PLUS dicloxacillin 500 mg four times daily 1
Why Cefdinir Fails
The IDSA guidelines explicitly state that first-generation cephalosporins have poor in vitro activity against P. multocida and should be avoided 1. While cefdinir is technically a third-generation cephalosporin, it appears only in guidelines for acute bacterial rhinosinusitis as an alternative for penicillin-allergic patients 1, not in any dog bite management guidelines 1, 2, 3.
The critical gap: Cefdinir lacks reliable coverage against the polymicrobial flora of dog bites, particularly anaerobes, which are present in 50-60% of dog bite wounds 1, 2. Using inadequate coverage against Pasteurella species leads to treatment failure 2.
Common Pitfall to Avoid
Do not use cephalexin, dicloxacillin alone, macrolides, or clindamycin monotherapy for dog bites, as these agents miss Pasteurella multocida coverage 1. If combination therapy is needed for beta-lactam allergy, options include clindamycin 300 mg three times daily PLUS a fluoroquinolone (ciprofloxacin or levofloxacin) 1.