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Difficulty: HardInfection Control and Hospital-Acquired Conditions

A 26-year-old male medical student is evaluating a 55-year-old man who was admitted to the hospital 1 day ago with a 3-week history of productive cough, low-grade fever, night sweats, and a 5-kg (11-lb) weight loss. The patient was initially placed on standard and droplet precautions for a suspected atypical bacterial respiratory infection. During the physical examination, the patient experiences paroxysms of coughing while the student is auscultating his lungs. The student is wearing a standard surgical mask, gown, and gloves. Later that afternoon, the patient's sputum acid-fast bacilli smear returns positive, and he is immediately transitioned to an airborne infection isolation room. The student is asymptomatic. A review of the student's occupational health records shows a negative interferon-gamma release assay (IGRA) documented 2 months ago during annual screening. Which of the following is the most appropriate next step in the management of this student?

  1. A
    Initiate a 4-month course of daily rifampin
  2. B
    Perform a baseline interferon-gamma release assay today
  3. C
    Place the student on administrative leave until follow-up testing is negative
  4. D
    Reassure the student that no follow-up is necessary because a surgical mask provides adequate protection
  5. Repeat the interferon-gamma release assay in 8 to 10 weeksAnswer

Answer

Repeat the interferon-gamma release assay in 8 to 10 weeks
The correct answer is repeating the interferon-gamma release assay in 8 to 10 weeks. This student had an unprotected exposure to active pulmonary tuberculosis because a standard surgical mask (droplet precautions) does not protect against airborne Mycobacterium tuberculosis transmission; an N95 respirator or powered air-purifying respirator (PAPR) is required. Following an unprotected exposure, asymptomatic healthcare workers must be evaluated for transmission. If a healthcare worker does not have a documented negative screening test within the past 12 months, a baseline test (IGRA or tuberculin skin test) should be drawn immediately. However, because this student had a documented negative test 2 months ago, a new baseline test is unnecessary. The appropriate management is to allow for the incubation period (the time required for a detectable cell-mediated immune response to develop) and perform follow-up testing 8 to 10 weeks after the exposure. If the follow-up test is positive, the student would then be evaluated for active disease and considered for latent tuberculosis infection treatment.

Step-by-Step Solution

1
Determine if a true infectious exposure occurred.
The student was exposed to active pulmonary tuberculosis while wearing a surgical mask.
Tuberculosis requires airborne precautions (N95 respirator or PAPR). A surgical mask only provides droplet protection, constituting an unprotected exposure to airborne droplet nuclei.
2
Assess the need for baseline post-exposure screening.
A baseline test is not required today.
The student has a documented negative interferon-gamma release assay from 2 months ago. Centers for Disease Control and Prevention (CDC) guidelines state that a documented negative test within the preceding 12 months serves as an adequate baseline.
3
Establish the correct timing for follow-up testing.
Follow-up testing should occur 8 to 10 weeks after the exposure.
It takes 8 to 10 weeks for the cell-mediated immune response to develop and for a tuberculosis screening test to predictably convert to positive following an exposure.

Key Concept

Occupational exposure to tuberculosis, personal protective equipment requirements, and timing of post-exposure screening in healthcare workers.
Estimated Time:1m 30s
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Topics

Infection Control and Hospital-Acquired Conditions

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