Tetanus Prophylaxis for Cat Bite
Give tetanus toxoid (Td or Tdap) without immunoglobulin and observe the cat for rabies signs. The patient's last tetanus vaccine was 7 years ago, which exceeds the 5-year interval for contaminated wounds, making a booster necessary. However, she does not need tetanus immunoglobulin (TIG) because she has a complete primary vaccination series. 1
Tetanus Management
The correct answer is E (Tetanus and rabies observation), though technically only tetanus vaccine is needed—rabies vaccine is not indicated for domestic cat bites in most circumstances.
Tetanus Prophylaxis Algorithm
Cat bites are classified as contaminated/tetanus-prone wounds because they may be contaminated with dirt, feces, soil, and saliva, and puncture wounds can create anaerobic conditions favorable for Clostridium tetani growth. 1
For patients with ≥3 previous doses and last dose ≥5 years ago: Administer tetanus toxoid-containing vaccine WITHOUT TIG. 1 The critical interval for contaminated wounds is 5 years, not the routine 10-year booster interval. 1, 2
Tdap is preferred over Td if the patient has not previously received Tdap or Tdap history is unknown, as this provides additional protection against pertussis. 3, 1
TIG is NOT required for patients with documented complete primary vaccination series (≥3 lifetime doses), even with contaminated wounds. 1 TIG would only be necessary if she had <3 lifetime doses, unknown vaccination history, or was severely immunocompromised. 1
Why Not Rabies Vaccine or Immunoglobulin?
Domestic cat bites in the United States typically do not require rabies post-exposure prophylaxis when the cat is available for observation. The standard approach is to observe the cat for 10 days for signs of rabies. [@general medical knowledge@]
Rabies vaccine alone (Option A) or with immunoglobulin (Option B) would only be indicated if the cat were unavailable for observation, showed signs of rabies, or if this occurred in a rabies-endemic area with high-risk circumstances. [@general medical knowledge@]
Critical Clinical Pearls
The most common error in tetanus prophylaxis is confusing the 10-year routine booster interval with the 5-year interval for contaminated wounds. 1 This patient's wound occurred 7 years after her last vaccine, exceeding the 5-year threshold for contaminated wounds.
The swelling despite antibiotics is concerning for inadequate wound management but does not change tetanus prophylaxis recommendations. Proper wound cleaning and debridement are critical components of tetanus prevention. 4
Complete primary vaccination provides nearly 100% protection and antitoxin antibodies develop rapidly after booster administration in previously vaccinated individuals. 1 This is why TIG is unnecessary in this patient.
Persons who have received at least two doses of tetanus toxoid rapidly develop antitoxin antibodies after a booster dose. 3
Wound Management Considerations
Ensure proper wound care including thorough cleaning and debridement to remove debris that might harbor Clostridium tetani spores. 4
Antibiotic prophylaxis is NOT indicated for tetanus prevention in most wounds, though it may be appropriate for preventing bacterial wound infection from the cat bite itself. 1
When administering tetanus toxoid, use separate syringes at different anatomical sites if TIG were also needed (though not in this case). 3