What tetanus vaccination and antibiotic regimen should be administered to a 14-year-old female with a foot laceration from a lake rock?

Tetanus Prophylaxis and Antibiotic Treatment for a 14-Year-Old with Lake Water Laceration

For a 14-year-old female with a foot laceration from a rock in a lake, administer Tdap (tetanus, diphtheria, acellular pertussis) vaccine if she has not received it within the past 5 years, and prescribe metronidazole to cover potential freshwater pathogens. 1

Tetanus Vaccination Management

Assessment of Tetanus Immunization Status

• Determine the patient's tetanus vaccination history:
  • Complete history (3+ doses): Give Tdap if last dose was >5 years ago
  • Incomplete/unknown history (<3 doses): Give Tdap AND tetanus immune globulin (TIG) 250 IU IM 2, 1

Vaccine Selection for Adolescents

• Tdap is the preferred vaccine for adolescents aged 11-18 years who have not previously received it 2
• This provides protection against tetanus, diphtheria, and pertussis in a single dose
• If the patient has already received Tdap previously, use Td (tetanus and diphtheria) for wound prophylaxis 2

Contraindications for Tdap

• History of severe allergic reaction to any vaccine component
• History of encephalopathy within 7 days of previous pertussis vaccination 2
• In these cases, administer Td instead of Tdap 2

Wound Management

Wound Cleaning

• Immediate and thorough wound cleaning is critical for tetanus prevention 1, 3
• Irrigate the wound gently with clean water or diluted iodopovidone solution 1
• Perform careful debridement of any devitalized tissue 3

Risk Assessment

• Lake water wounds are considered contaminated and at higher risk for tetanus 1
• Puncture wounds, contamination with dirt/soil, and wounds with devitalized tissue are particularly tetanus-prone 1

Antibiotic Selection

Primary Recommendation

• Metronidazole is the preferred antibiotic for freshwater wounds with potential anaerobic contamination 1, 4
  • Dosing for 14-year-old: 500 mg PO three times daily for 7-10 days
  • Metronidazole is more effective than penicillin G against Clostridium tetani 4, 5

Alternative Options

• If metronidazole is contraindicated:
  • Doxycycline (if ≥8 years old): 100 mg PO twice daily for 7-10 days 1
  • Amoxicillin-clavulanate to cover both anaerobes and gram-negative organisms

Follow-up Care

• Monitor the wound for signs of infection (increasing pain, redness, swelling, purulent drainage)
• Instruct patient to seek immediate medical attention if developing muscle stiffness, difficulty swallowing, or spasms
• Complete the full course of antibiotics even if symptoms improve

Common Pitfalls to Avoid

1. Failing to administer TIG in patients with unknown/incomplete vaccination history
2. Using penicillin as first-line therapy (metronidazole is superior for tetanus prophylaxis) 4, 5
3. Inadequate wound cleaning and debridement, which is as important as immunization 1, 3
4. Forgetting to update the patient's vaccination record after administering Tdap

This approach prioritizes prevention of tetanus through appropriate vaccination and wound care while providing effective antibiotic coverage for potential pathogens in lake water, thereby minimizing morbidity and mortality risks.