What is the recommended treatment for a rat bite?

Rat Bite Treatment

For rat bites, immediately irrigate the wound thoroughly with water or saline, provide tetanus prophylaxis if needed, and avoid routine prophylactic antibiotics since infection rates are only 2% in uninfected wounds. 1, 2

Immediate Wound Management

Wound cleansing is the single most critical intervention and should be performed immediately:

• Irrigate copiously with water or sterile normal saline to remove debris and reduce bacterial load 1, 3
• Use gentle irrigation technique—avoid high-pressure irrigation as this can drive bacteria deeper into tissues 1
• Clean with soap and water, then apply a virucidal agent 1
• Remove superficial debris only; avoid aggressive debridement that could enlarge the wound 3
• Do not suture rat bite wounds as closure increases infection risk 1, 3
• For facial wounds requiring cosmetic closure, this should only be done by a specialist after meticulous wound care, copious irrigation, and administration of prophylactic antibiotics 3

Tetanus Prophylaxis

• Administer tetanus toxoid (0.5 mL intramuscularly) if vaccination status is outdated or unknown 3, 1
• This is mandatory as most rat bite patients are deficient in tetanus immunity 2

Antibiotic Considerations

Prophylactic antibiotics are NOT routinely recommended for clean, uninfected rat bites:

• A prospective study of 50 rat bite patients showed only 2% developed infection without prophylactic antibiotics 2
• Bacterial cultures from rat bites most commonly grow Staphylococcus epidermidis (43%), with other organisms including Bacillus subtilis, diphtheroids, and alpha-hemolytic Streptococcus 2

Antibiotics ARE indicated for:

• Deep wounds 1
• Wounds in critical areas (hands, feet, joints, face, genitals) 1
• Patients with elevated infection risk (immunocompromised, diabetes, prosthetic joints) 1
• Patients with implants 1
• Signs of established infection 2

When antibiotics are indicated:

• First-line oral therapy: Amoxicillin-clavulanate for 3-5 days 4, 1
• Alternative: Cephalosporin or penicillinase-resistant penicillin 2
• For penicillin allergy: Doxycycline, or fluoroquinolone plus metronidazole or clindamycin 4
• For severe infections requiring IV therapy: Ampicillin-sulbactam or piperacillin-tazobactam 4

Rabies Assessment

Rabies prophylaxis is generally NOT required for rat bites:

• Rabies transmission from rats is extraordinarily rare in the United States 4
• Consult your local health department about rabies prevalence in wild or feral rats in your specific geographic area 3, 1
• If rabies exposure is suspected (which is exceptional), administer both rabies immune globulin (20 IU/kg) and vaccine series on days 0,3,7,14, and 28 3, 4

Risk Stratification by Wound Type

A classification system helps guide treatment intensity 5:

• Type I (superficial scratches): Conservative wound care only, no antibiotics needed 5
• Type II (deeper bites with infection/ulceration): May require drainage and debridement; consider antibiotics 5
• Type III (full-thickness with tissue loss): Requires surgical intervention including possible skin grafting 5

Special Considerations for Rat Bite Fever

Be aware of Streptobacillus moniliformis infection (rat bite fever):

• Can occur even without fever or rash, making diagnosis challenging 6
• Presents with fever, rigors, myalgias, headache, and maculopapular rash 6
• Polyarthritis develops in up to 50% of cases 6
• Potentially lethal but easily treatable with appropriate antibiotics 6
• Consider this diagnosis if systemic symptoms develop days to weeks after the bite 7

Follow-Up

• Evaluate within 24 hours by phone or office visit 3, 1
• Monitor for signs of infection: increasing pain, erythema, swelling, purulent drainage 1
• Elevate the injured extremity if swollen 3
• Consider hospitalization if infection progresses despite appropriate therapy 3

Common Pitfalls to Avoid

• Delaying wound cleansing—this is the most critical intervention 1
• Routinely prescribing prophylactic antibiotics when infection rate is only 2% 2
• Suturing wounds, which increases infection risk 1
• Using high-pressure irrigation that drives bacteria deeper 1
• Overlooking tetanus status 2
• Failing to recognize that 72% of rat bites occur during sleep, typically affecting exposed areas of upper extremities and face 2