What is the recommended management for a patient presenting with a rat bite, considering potential infection and tetanus risk?

Management of Rat Bite

For rat bites, immediately irrigate the wound with sterile normal saline, administer amoxicillin-clavulanate 875/125 mg twice daily for 3-5 days for high-risk wounds (hand, face, near joints, or presenting >8-12 hours after injury), and ensure tetanus prophylaxis is current. 1

Immediate Wound Care

• Copiously irrigate the wound with sterile normal saline using a 20-mL or larger syringe to generate adequate pressure and remove bacterial load 2, 3
• Remove only superficial debris; avoid aggressive debridement that could enlarge the wound and impair closure 4
• Do not use iodine- or antibiotic-containing solutions for routine wound cleansing 4, 2
• Explore the wound for foreign bodies, tendon involvement, or bone penetration 3

Antibiotic Prophylaxis Decision

High-risk wounds requiring antibiotics include: 1, 4

• Wounds involving the hand, face, or areas near joints
• Wounds with signs of infection (erythema, purulent discharge, warmth)
• Immunocompromised patients or those with advanced liver disease
• Wounds presenting >8-12 hours after injury
• Deep puncture wounds or wounds that may have penetrated periosteum or joint capsule

Low-risk wounds (superficial, clean, presenting early) do not require prophylactic antibiotics 5. A prospective study of 50 uninfected rat bite wounds found only a 2% infection rate without prophylactic antibiotics, supporting selective rather than universal antibiotic use 5.

First-Line Antibiotic Regimen

• Amoxicillin-clavulanate 875/125 mg orally twice daily is the first-line antibiotic, providing essential coverage against Staphylococcus, Streptococcus, anaerobes, and gram-negative organisms commonly found in rat bite wounds 1, 4
• For penicillin-allergic patients, use doxycycline 100 mg orally twice daily 1
• Alternative regimens include a fluoroquinolone (ciprofloxacin, levofloxacin, moxifloxacin) plus metronidazole or clindamycin for anaerobic coverage 4

Avoid these antibiotics due to inadequate coverage: 4

• First-generation cephalosporins (cephalexin)
• Penicillinase-resistant penicillins alone (dicloxacillin)
• Macrolides (erythromycin)
• Clindamycin alone

Duration of Antibiotic Therapy

• Prophylaxis for high-risk wounds: 3-5 days 1, 4
• Established infection: 7-10 days 1
• Septic arthritis: 3-4 weeks 1, 4
• Osteomyelitis: 4-6 weeks 1, 4

Wound Closure Guidelines

• Do not close infected wounds or wounds with purulent discharge 4
• Facial wounds may be closed primarily after meticulous irrigation and debridement with concurrent prophylactic antibiotics 4, 2
• For other wounds, approximate margins with Steri-Strips and allow closure by delayed primary or secondary intent 4
• Suturing wounds early (<8 hours after injury) is controversial; when in doubt, avoid primary closure 4

Tetanus Prophylaxis

Tetanus prophylaxis is mandatory for all rat bites 5, 6:

• Administer tetanus toxoid 0.5 mL intramuscularly if vaccination status is outdated (>10 years for clean wounds, >5 years for dirty wounds) or unknown 4, 7
• Tdap is preferred over Td if not previously given 4
• For patients with unknown or incomplete primary vaccination (<3 doses), administer both tetanus toxoid and Tetanus Immune Globulin (TIG) 7
• A recent case report highlighted that failure to administer tetanus prophylaxis for a high-risk wound in a patient whose last booster was >5 years prior resulted in severe generalized tetanus 8

Rabies Prophylaxis

• Rabies prophylaxis is generally NOT required for domestic rat bites in the United States 1, 2
• Small mammals including domestic rats are rarely infected with rabies 2
• Consult local health department for regional risk assessment, especially for wild or feral rat bites 4, 1
• If indicated, administer rabies immunoglobulin (20 IU/kg body weight infiltrated around the wound) on day 0, followed by rabies vaccine on days 0,3,7, and 14 at a different site 4, 3

Severe Infections Requiring IV Therapy

For severe infections with systemic signs (fever, lymphangitis, bacteremia), hospitalize and initiate IV antibiotics: 4

• Ampicillin-sulbactam 3 g IV every 6 hours
• Piperacillin-tazobactam 3.37 g IV every 6-8 hours
• Ertapenem 1 g IV daily
• Imipenem or meropenem 1 g IV every 6-8 hours

Follow-Up and Monitoring

• Elevate the injured extremity to reduce swelling 4, 2
• Follow up within 24 hours by phone or office visit for all outpatients 4
• Monitor for signs of infection progression: increasing pain, redness, swelling, purulent discharge, fever 2
• Pain disproportionate to injury near a bone or joint suggests periosteal penetration or septic arthritis 4
• Hand wounds are often more serious than wounds to fleshy body parts and require closer monitoring 4

Critical Pitfalls to Avoid

• Delaying antibiotic therapy in high-risk wounds can lead to septic arthritis, osteomyelitis, or bacteremia 1, 4
• Using antibiotics without anaerobic coverage (e.g., first-generation cephalosporins alone) will miss important pathogens 1, 4
• Failing to update tetanus prophylaxis, especially for wounds >5 years since last booster, can result in severe tetanus 8, 7
• Primary closure of infected or high-risk wounds increases infection risk 4