What are the treatment guidelines for a rat bite?

Rat Bite Management Guidelines

Immediate Wound Care

Irrigate the wound immediately and thoroughly with copious amounts of sterile normal saline or water—this is the single most important intervention to prevent infection. 1

• Do not use iodine- or antibiotic-containing solutions for routine cleansing 1
• Remove only superficial debris; avoid aggressive debridement as it may enlarge the wound unnecessarily 1
• Do not close infected wounds 1
• For clean wounds seen within 8 hours, approximate edges with Steri-Strips rather than sutures, allowing for delayed primary or secondary closure 1
• Facial wounds are an exception and may be closed primarily after meticulous care and prophylactic antibiotics 1

Antibiotic Prophylaxis Decision

Most uninfected rat bites do not require prophylactic antibiotics. The natural infection rate is only 2% with proper wound care alone 2. However, this recommendation requires careful risk stratification:

When to Withhold Prophylactic Antibiotics:

• Superficial scratches (Type I wounds) with no signs of infection 3
• Clean wounds with proper irrigation performed immediately 2
• Immunocompetent patients with good follow-up 1

When to Prescribe Prophylactic Antibiotics:

• Deep bites with tissue damage (Type II or III wounds) 3
• Wounds with signs of infection or ulceration 3
• Immunocompromised patients 1
• Delayed presentation (>8 hours) 1
• Hand wounds or wounds near joints/bones 4

Antibiotic Selection

For Infected Wounds (First-Line):

Amoxicillin-clavulanate is the preferred oral antibiotic for infected rat bites. 1

Alternative Oral Options:

• Cephalosporins (first or second generation) 2
• Penicillinase-resistant penicillins 2
• Doxycycline 1
• Fluoroquinolones (ciprofloxacin, levofloxacin, moxifloxacin) 1

Intravenous Therapy (for severe infections):

• Ampicillin-sulbactam (first-line) 1
• Piperacillin-tazobactam 1
• Second-generation cephalosporins (cefoxitin) 1
• Carbapenems (ertapenem, imipenem, meropenem) 1

Treatment Duration:

• Standard wound infections: 7-10 days 1
• Septic arthritis: 3-4 weeks 1
• Osteomyelitis: 4-6 weeks 1

Tetanus Prophylaxis

Tetanus prophylaxis is mandatory for all rat bites. 1, 2

• Administer tetanus toxoid 0.5 mL intramuscularly if vaccination status is outdated or unknown 1
• For dirty wounds: booster needed if >5 years since last dose 1
• For clean wounds: booster needed if >10 years since last dose 1

Rabies Prophylaxis

Rabies prophylaxis is generally NOT required for domestic rat bites in the United States, as small rodents are rarely infected with rabies. 1

• Consult local health department for regional risk assessment 1
• Consider prophylaxis only for feral or wild rodent bites in high-prevalence areas 1
• If indicated, administer rabies immunoglobulin and vaccine series 1

Adjunctive Measures

• Elevate the injured extremity to reduce swelling and accelerate healing 1
• Follow up within 24 hours by phone or office visit for all outpatients 1

Hospitalization Criteria

Hospitalize if any of the following occur: 1

• Infection progresses despite appropriate antimicrobial therapy
• Deep tissue involvement is suspected (septic arthritis, osteomyelitis, tenosynovitis)
• Patient is immunocompromised or has significant comorbidities
• Type III wounds requiring skin grafting 3

Common Pitfalls

• Most rat bites occur during sleep (72%) and involve exposed areas like hands and face 2—educate patients about prevention
• Rat bite fever (Streptobacillus moniliformis) can present without fever or rash, making diagnosis difficult 5—maintain high suspicion for systemic symptoms developing days to weeks after the bite
• Rat bite fever carries a 10% mortality if untreated 6—any systemic symptoms (fever, rigors, polyarthralgias, rash) warrant immediate evaluation and treatment with penicillin or doxycycline
• Hand wounds near joints require expert evaluation for potential penetration into synovium or bone 4