What is the treatment for a rat bite?

Rat Bite Treatment

Immediately wash the wound thoroughly with soap and water for at least 15 minutes, administer tetanus prophylaxis if needed, and use amoxicillin-clavulanate only for infected wounds—prophylactic antibiotics are NOT routinely recommended for clean rat bites due to their low infection rate. 1

Immediate Wound Care

• Irrigate the wound copiously with soap and water for at least 15 minutes, as this mechanical cleansing is the single most effective intervention to reduce infection risk, more so than any antibiotic therapy 1
• Follow with sterile normal saline irrigation to remove debris and reduce bacterial load 1
• Do NOT close infected wounds; for clean wounds presenting within 8 hours, approximate edges with Steri-Strips rather than sutures to allow drainage 1
• Facial wounds are the exception and may be closed primarily after meticulous irrigation and prophylactic antibiotics 1

Tetanus Prophylaxis

• Administer tetanus toxoid (0.5 mL intramuscularly) if vaccination status is outdated or unknown, as this is mandatory for all rat bite patients 1
• This is particularly important since most rat bite victims have deficient tetanus immunity 2

Rabies Assessment

• Rabies prophylaxis is NOT required for rat bites in the United States, as small rodents including rats are not considered significant rabies vectors 1
• Only in exceptional circumstances where rabies exposure is suspected should you consider prophylaxis with both rabies immune globulin (20 IU/kg) and a 4-dose vaccine series on days 0,3,7, and 14 1

Antibiotic Management: A Risk-Stratified Approach

For Clean, Uninfected Wounds:

• Prophylactic antibiotics are NOT recommended due to the naturally low infection rate of only 2% in uninfected rat bites 2
• Research demonstrates that only 30% of rat bite wounds yield bacterial isolates, with most being low-virulence organisms like Staphylococcus epidermidis 2
• Good surgical wound management alone is sufficient for most cases 2, 3

For Infected Wounds:

• Amoxicillin-clavulanate is the first-line oral antibiotic, providing broad coverage for the polymicrobial nature of these infections 1
• For penicillin allergy, use doxycycline, fluoroquinolones (ciprofloxacin, levofloxacin, moxifloxacin) plus metronidazole or clindamycin 1
• For severe infections requiring IV therapy, use ampicillin-sulbactam or piperacillin-tazobactam as first-line 1
• Alternative IV options include second-generation cephalosporins (cefoxitin) or carbapenems (ertapenem, imipenem, meropenem) 1

Wound Classification and Management

Research supports a classification system that guides treatment intensity 3:

• Type I (superficial scratches): Conservative wound care only, no antibiotics needed 3
• Type II (deeper bites with infection/ulceration): May require drainage and debridement if pus present, plus antibiotics 3
• Type III (full-thickness tissue loss): Requires skin grafting and surgical reconstruction 3

Follow-Up and Monitoring

• Elevate injured extremities if swollen to accelerate healing 1
• Follow up within 24 hours for all outpatients, either by phone or office visit 1
• Consider hospitalization if infection progresses despite appropriate antimicrobial therapy 1

Common Pitfalls to Avoid

• Do not routinely prescribe prophylactic antibiotics for clean wounds—this represents overtreatment given the 2% infection rate 2
• Do not suture infected wounds or wounds with tissue loss—this traps bacteria and increases infection risk 1
• Do not forget tetanus prophylaxis—this is often overlooked but mandatory 1, 2
• Be aware that 72% of rat bites occur during sleep, typically affecting exposed areas of upper extremities and face 2
• Remember that while most infections are polymicrobial, Staphylococcus aureus is the most common single isolate when infection does occur 4