What are the management and prophylaxis options for a patient with a rat bite who does not have fever?

Management of Rat Bite Without Fever

Even in the absence of fever, a patient with a rat bite requires antibiotic prophylaxis because rat-bite fever can present without fever and carries a 10% mortality rate if untreated. 1, 2

Antibiotic Prophylaxis

First-Line Treatment

• Administer amoxicillin-clavulanate as the first-line oral prophylactic antibiotic, following the same principles used for human bite wounds, which share similar polymicrobial infection risks 3
• For penicillin-allergic patients, use doxycycline as an alternative oral agent 3, 4
• Other alternatives for penicillin allergy include fluoroquinolones (ciprofloxacin, levofloxacin, moxifloxacin) combined with metronidazole or clindamycin for anaerobic coverage 3

Treatment Duration

• Continue antibiotic prophylaxis for 14 days to prevent development of rat-bite fever 4

Critical Clinical Context

Why Prophylaxis is Essential Even Without Fever

• Rat-bite fever caused by Streptobacillus moniliformis can present without fever, making the absence of fever an unreliable indicator for withholding treatment 1
• The disease carries a 10% mortality rate if left untreated, but is easily treatable when recognized 1, 2
• Diagnosis is particularly difficult because the causative bacteria are not easily identified with standard blood cultures and testing 4, 2
• Polyarthritis develops in up to 50% of cases and can be the presenting feature even without fever 1

Wound Management

• Immediately irrigate the bite wound with copious amounts of sterile normal saline 3
• Do not close infected wounds; for clean wounds seen early (<8 hours), consider approximation with Steri-Strips rather than sutures 3
• Elevate the injured body part if swollen 3

Tetanus Prophylaxis

• Ensure tetanus immunization is current 3
• Administer tetanus toxoid (0.5 mL intramuscularly) if vaccination status is outdated or unknown 3

Rabies Considerations

• Rabies prophylaxis is not indicated for rat bites, as rodents (including rats) are not significant rabies vectors 3
• The guidelines specifically note that rabies transmission from rodent bites is extraordinarily rare and typically not a concern 3

Follow-Up Protocol

• Schedule follow-up within 24 hours either by phone or office visit 3
• Monitor for development of fever, rash (maculopapular or petechial), polyarthralgia, or systemic symptoms that would indicate progression to rat-bite fever 4, 1
• If infection develops despite prophylaxis, consider hospitalization and intravenous antibiotics with β-lactam/β-lactamase combinations (ampicillin-sulbactam or piperacillin-tazobactam) 3

Common Pitfalls to Avoid

• Do not withhold antibiotics based on absence of fever alone - rat-bite fever can present without fever and diagnosis is often delayed due to this misconception 1
• Do not rely on standard blood cultures to rule out infection - S. moniliformis requires specialized culture techniques and may not grow on routine media 4, 2
• Do not underestimate the severity - complications can include septic arthritis, endocarditis, and death if untreated 2, 5