Management of Rat Scratch Wound
For this clean rat scratch, administer tetanus toxoid if the patient has not received a dose within the past 10 years (or within 5 years for tetanus-prone wounds), continue mupirocin ointment three times daily, and rabies prophylaxis is NOT indicated for rodent exposures in the United States. 1, 2
Tetanus Immunization
Tetanus prophylaxis is essential and depends on the patient's vaccination history:
If the patient has completed primary tetanus vaccination (≥3 doses): Administer tetanus toxoid (Td or Tdap preferred) ONLY if more than 10 years have elapsed since the last dose for clean minor wounds, or more than 5 years for contaminated/tetanus-prone wounds 1, 3
If vaccination history is unknown or incomplete (<3 doses): Administer both tetanus toxoid AND Tetanus Immune Globulin (TIG) 250 units IM at a separate site 1, 3
Tdap is preferred over Td if the patient has not previously received Tdap, as this enhances diphtheria and pertussis protection 3
The wound should be classified: While described as "clean," a rat scratch on the foot that penetrated skin should be managed conservatively as a potentially contaminated wound, warranting the 5-year booster interval rather than 10-year 1
Wound Care and Topical Antibiotic
Continue mupirocin 2% ointment as already initiated:
Apply a small amount to the affected area three times daily 2
The area may be covered with gauze dressing if desired 2
Re-evaluate within 3-5 days if no clinical improvement is observed 2
Mupirocin has excellent activity against staphylococci and streptococci, the predominant pathogens in superficial skin infections, with clinical cure or marked improvement in 80-100% of cases 4, 5
Wound cleansing principles:
The wound has already been appropriately washed with soap and water 1
Avoid primary closure of animal bite/scratch wounds except for facial wounds managed by specialists 1
Wound margins may be approximated with Steri-Strips if needed 1
Antibiotic Prophylaxis
Preemptive systemic antibiotic prophylaxis for 3-5 days is recommended for patients with:
- Moderate to severe injuries, especially to the hand or face 1
- Injuries that may have penetrated periosteum or joint capsule 1
- Immunocompromised status, asplenia, or advanced liver disease 1
- Preexisting or resultant edema of the affected area 1
For this case: A 2cm superficial scratch on the foot in an immunocompetent patient does NOT meet criteria for systemic prophylactic antibiotics 1. The topical mupirocin is appropriate and sufficient 2.
If systemic antibiotics were indicated, amoxicillin-clavulanate would be the agent of choice to cover both aerobic and anaerobic bacteria 1.
Rabies Considerations
Rabies prophylaxis is NOT indicated for rodent exposures:
Small rodents (including rats, mice, squirrels, hamsters, guinea pigs, gerbils, chipmunks) are almost never found to be infected with rabies and have not been known to transmit rabies to humans in the United States 1
Consultation with local health officials is recommended only for exposures to carnivores (dogs, cats, ferrets, raccoons, skunks, foxes, bats) or livestock 1
Do not initiate rabies postexposure prophylaxis for this rat scratch 1
Follow-up
Reassess within 24 hours by phone or office visit to ensure no signs of infection develop 1
Watch for signs of infection: increasing pain, erythema, warmth, purulent discharge, fever 1
If infection progresses despite appropriate therapy, consider hospitalization and systemic antibiotics 1
Common Pitfalls to Avoid
Do not assume tetanus immunity without documentation – patients with unknown vaccination history should be treated as unvaccinated 1, 3
Do not administer rabies prophylaxis for rodent bites/scratches – this is unnecessary and exposes the patient to risk without benefit 1
Do not suture the wound – animal scratches/bites should heal by secondary intention except for facial wounds 1
Do not use tetanus toxoid alone if the patient is unvaccinated or incompletely vaccinated with a contaminated wound – TIG is also required 1, 3