What is the recommended treatment for a rat bite?

Treatment for Rat Bite

For rat bites, perform thorough wound irrigation with sterile saline, provide tetanus prophylaxis if needed, and avoid routine prophylactic antibiotics unless the wound shows signs of infection or involves high-risk features. 1, 2

Immediate Wound Management

Wound cleansing is the cornerstone of rat bite treatment and takes priority over antibiotic administration. 1

• Irrigate the wound immediately and thoroughly with sterile normal saline or water to remove debris and reduce bacterial load 1
• Avoid using iodine- or antibiotic-containing solutions for routine cleansing 1
• Remove only superficial debris; deeper debridement is usually unnecessary and should be done cautiously to avoid enlarging the wound 1
• Do not close infected wounds 1
• For clean wounds seen early (<8 hours), approximation with Steri-Strips rather than sutures is preferred, with delayed primary or secondary closure 1
• Facial wounds are an exception and may be closed primarily after meticulous care and prophylactic antibiotics 1

Antibiotic Therapy

Prophylactic antibiotics are NOT routinely recommended for uninfected rat bites due to the low natural infection rate of approximately 2%. 2

When Antibiotics Are NOT Needed:

• Type I wounds (superficial scratches) require only conservative wound care 3
• Clean, uninfected bites with good wound care 2

When Antibiotics ARE Indicated:

• Type II wounds (deeper bites with infection or ulceration) 3
• Type III wounds (full-thickness with tissue loss) 3
• Signs of established infection 2
• High-risk wounds (hand injuries, immunocompromised patients, delayed presentation) 1

Antibiotic Selection for Infected Rat Bites:

First-line oral therapy: 1

• Amoxicillin-clavulanate (provides coverage for typical wound pathogens and anaerobes) 1, 4

Alternative oral options: 1, 2

• Cephalosporins (cephalexin) or penicillinase-resistant penicillins (dicloxacillin) for established infections 2
• Doxycycline for penicillin-allergic patients 1
• Fluoroquinolones (ciprofloxacin, levofloxacin, moxifloxacin) plus metronidazole or clindamycin 1

Intravenous therapy (for severe infections): 1

• Ampicillin-sulbactam or piperacillin-tazobactam 1, 4
• Second-generation cephalosporins (cefoxitin) 1
• Carbapenems (ertapenem, imipenem, meropenem) 1

Tetanus Prophylaxis

Tetanus prophylaxis is mandatory for rat bites. 1, 2

• Administer tetanus toxoid 0.5 mL intramuscularly if vaccination status is outdated or unknown 1
• For dirty wounds: booster if >5 years since last dose 1
• For clean wounds: booster if >10 years since last dose 1
• Tdap is preferred over Td if not previously given 1

Rabies Prophylaxis

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

• Consult local health department about regional rabies prevalence and specific risk assessment 1
• Consider prophylaxis only for feral or wild rodent bites in high-prevalence areas 1
• If indicated: administer rabies immunoglobulin (20 IU/kg) on day 0, infiltrated around the wound, plus rabies vaccine on days 0,3,7,14, and 28 1

Special Considerations and Follow-Up

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 is indicated if: 1

• Infection progresses despite appropriate antimicrobial therapy 1
• Deep tissue involvement (tendon, joint, bone) is suspected 1
• Patient is immunocompromised or has significant comorbidities 1

Surgical Management by Wound Type

Type I (superficial scratches): Conservative wound care only, no antibiotics or surgery needed 3

Type II (deeper bites with infection/ulceration): May require urgent drainage and debridement if pus is present 3

Type III (full-thickness with tissue loss): Requires skin grafting after initial wound management 3

Common Pitfalls to Avoid

• Do not routinely prescribe prophylactic antibiotics for clean, uninfected rat bites—this leads to unnecessary antibiotic exposure with a natural infection rate of only 2% 2
• Do not suture rat bite wounds except facial wounds under specific conditions 1
• Do not forget tetanus prophylaxis—most rat bite patients have deficient tetanus immunity 2
• Do not assume rabies risk is high—domestic rats rarely carry rabies, unlike dogs, cats, bats, and wild carnivores 1
• Be aware that most rat bites occur during sleep (72% of cases) and typically affect exposed areas like hands and face 2

Duration of Antibiotic Therapy

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

Rat Bite Fever Consideration

While rare, rat bite fever (caused by Streptobacillus moniliformis) should be considered if fever develops after rat exposure 5, 6

• Presents as fever syndrome, often with arthritis 5
• Penicillin is the treatment of choice for rat bite fever 5, 6
• Blood cultures should be obtained if persistent fever develops, even without systemic inflammatory response 5
• 16S ribosomal RNA PCR is more sensitive than standard cultures 5