Rat Bite Treatment
For a rat bite, immediately irrigate the wound thoroughly with copious amounts of sterile saline or water, administer amoxicillin-clavulanate as first-line antibiotic therapy (especially for hand wounds or wounds near joints), and ensure tetanus prophylaxis is current. 1
Immediate Wound Management
Irrigate the wound immediately and thoroughly with sterile normal saline or water to remove debris and reduce bacterial load—this is the cornerstone of treatment and takes priority over antibiotic administration. 1
Clean the wound to remove only superficial debris; avoid iodine- or antibiotic-containing solutions for routine cleansing, as these are not recommended. 1
Do not close infected wounds. For clean wounds seen early (within 8 hours), use Steri-Strips rather than sutures for approximation, with consideration for delayed primary or secondary closure. 1
Facial wounds are the exception and may be closed primarily after meticulous wound care and prophylactic antibiotics. 1
Antibiotic Therapy
Amoxicillin-clavulanate is the first-line oral antibiotic for rat bites, providing coverage for typical wound pathogens including both aerobic and anaerobic bacteria. 1 This is particularly important given that rat bite infections are frequently polymicrobial, with Staphylococcus aureus being the most common isolate but 72.5% of infections involving multiple bacterial species. 2
Oral Antibiotic Options:
- First-line: Amoxicillin-clavulanate 1
- Alternatives for established infections: Cephalosporins, penicillinase-resistant penicillins, doxycycline, or fluoroquinolones 1
Intravenous Therapy (for severe infections):
- Ampicillin-sulbactam, piperacillin-tazobactam, second-generation cephalosporins (cefoxitin), or carbapenems 1
When Antibiotics Are Mandatory:
- Hand wounds or wounds near joints/bones require prophylactic antibiotics due to high risk of infection and potential penetration into synovium or bone. 1
- These wounds require expert evaluation and may necessitate hospitalization with intravenous antibiotics. 1
Duration of Treatment:
Important caveat: While one pediatric study suggested most rat bites don't require antibiotics or hospitalization with conservative wound care alone 3, this conflicts with guideline recommendations. Given the potential for serious complications including rat bite fever (which can progress to fatal endocarditis despite aggressive therapy 4) and the polymicrobial nature of these infections 2, err on the side of antibiotic prophylaxis, particularly for high-risk wounds.
Tetanus Prophylaxis
Tetanus prophylaxis is mandatory for all rat bites. 1
Administer tetanus toxoid 0.5 mL intramuscularly if vaccination status is outdated or unknown. 1
For dirty wounds, a booster is needed if more than 5 years since last dose; for clean wounds, if more than 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 departments for regional risk assessment. 1
Consider prophylaxis only for feral or wild rodent bites in high-prevalence areas; if indicated, administer rabies immunoglobulin and vaccine. 1
Follow-Up and Special Considerations
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
Hospitalize if: infection progresses despite appropriate antimicrobial therapy, deep tissue involvement is suspected, or the patient is immunocompromised or has significant comorbidities. 1
Common Pitfalls to Avoid
Inadequate irrigation is a major cause of subsequent infection—the mechanical action of copious irrigation is critical. 1
Missing rat bite fever: This can present without fever or rash in some cases, making diagnosis difficult, but it is potentially lethal if untreated. 5 Maintain high clinical suspicion for flu-like illness following rat exposure, as it can progress to endocarditis. 4
Underestimating infection risk: Given the deep puncturing nature of rodent bites and polymicrobial bacterial flora, these should be considered high risk for infection. 2