What is the management for a nurse with a purified protein derivative (PPD) induration of 11mm, no symptoms, and an unremarkable chest radiograph?

Management of Latent Tuberculosis Infection in a Nurse with 11mm PPD Induration

A nurse with a PPD induration of 11mm, no symptoms, and an unremarkable chest radiograph should receive treatment for latent tuberculosis infection (LTBI) with isoniazid for 9 months as the preferred regimen. 1

Diagnosis Confirmation

The nurse's presentation meets the criteria for LTBI based on:

• PPD induration of 11mm (≥10mm is considered positive for healthcare workers) 1
• Absence of symptoms suggestive of active TB
• Normal chest radiograph excluding active disease
• Healthcare worker status (occupational risk factor)

Treatment Options

Preferred Regimen:

• Isoniazid (INH) for 9 months - 300mg daily for adults 1, 2
  • Highest efficacy rating (A-II) for both HIV-negative and HIV-positive patients
  • Most extensively studied regimen with proven long-term efficacy

Alternative Regimens:

1. Rifampin for 4 months - Rating B (II) for HIV-negative individuals 1
2. Isoniazid plus rifapentine - Weekly directly observed therapy for 3 months 3
3. Isoniazid plus rifampin for 3-4 months 1

Monitoring During Treatment

• Baseline liver function tests recommended for healthcare workers 1
• Regular monitoring for signs and symptoms of hepatotoxicity:
  • Monthly clinical evaluation for symptoms (fatigue, anorexia, nausea, abdominal discomfort, dark urine)
  • Periodic liver function tests for patients over 35 years of age or with risk factors for hepatotoxicity 1
• Withhold isoniazid if:
  • Transaminase levels exceed 3× upper limit of normal with symptoms
  • Transaminase levels exceed 5× upper limit of normal without symptoms 1

Special Considerations for Healthcare Workers

• Healthcare workers represent a high-risk group due to potential exposure to TB patients 4
• Treatment of LTBI in healthcare workers is crucial for preventing nosocomial TB transmission 4
• Despite recommendations, healthcare workers have historically been less likely to initiate LTBI treatment (adjusted odds ratio 0.55) 5
• Emphasize importance of treatment completion to prevent progression to active disease and potential transmission to vulnerable patients

Follow-up

• No routine follow-up chest radiographs needed if asymptomatic during and after treatment
• Educate about symptoms of active TB that would warrant immediate evaluation
• No need for repeat PPD testing after documented infection and appropriate treatment

Pitfalls to Avoid

1. Delaying treatment - Without treatment, LTBI will progress to active TB disease in 5-10% of affected individuals 3
2. Inadequate monitoring - Failure to monitor for hepatotoxicity, especially in older adults
3. Poor adherence - Consider directly observed therapy if adherence concerns exist
4. Misdiagnosing active TB - Ensure active TB is fully excluded before starting LTBI treatment
5. Not reporting the case - All cases of LTBI in healthcare workers should be reported to appropriate occupational health and public health authorities 1

The implementation of LTBI screening and treatment programs has been shown to significantly reduce the incidence of active TB among healthcare workers 4, making treatment of this nurse's LTBI an important intervention both for individual health and institutional infection control.