What precautions should be taken when a patient with a positive Tuberculin Skin Test (TST) and close contact with a Tuberculosis (TB) positive person presents to the clinic for a chest X-ray?

From the Guidelines

When a patient with a positive T-SPOT test and TB exposure history comes for a chest X-ray, healthcare providers should implement airborne precautions immediately. The patient should wear a surgical mask upon arrival and be placed in a negative pressure isolation room if available. Healthcare staff should wear N95 respirators or higher-level protection when interacting with the patient. The chest X-ray should be performed promptly, with minimal waiting time in public areas. After imaging, the room should be left vacant for at least 15-30 minutes to allow for air exchange before cleaning. These precautions are necessary because a positive T-SPOT indicates TB infection, and close contact with an active TB case increases the risk of active disease. While latent TB is not contagious, the patient's status is unknown until the chest X-ray and clinical evaluation are complete. The X-ray will help determine if there are pulmonary infiltrates or cavitations suggestive of active TB. If active TB is suspected based on imaging, the patient should remain masked and be evaluated for respiratory isolation, sputum collection for acid-fast bacilli smear and culture, and potential initiation of anti-tuberculosis therapy pending final results, as recommended by the American Thoracic Society/ Centers for Disease Control and Prevention/Infectious Diseases Society of America 1. Key considerations include:

• Implementing airborne precautions to prevent potential transmission of TB
• Performing a chest X-ray to evaluate for signs of active TB, such as pulmonary infiltrates or cavitations
• Considering the patient's HIV status and potential for immunocompromisation, as this may affect the interpretation of the T-SPOT test and chest X-ray results, as noted in the guidelines for preventing opportunistic infections among HIV-infected persons 1
• Following up with further testing and evaluation as needed to confirm the diagnosis and guide treatment, according to the ACR Appropriateness Criteria for imaging of possible tuberculosis 1.

From the FDA Drug Label

1. Close contacts of persons with newly diagnosed infectious tuberculosis (≥ 5 mm) In addition, tuberculin-negative (< 5mm) children and adolescents who have been close contacts of infectious persons within the past 3 months are candidates for preventive therapy until a repeat tuberculin skin test is done 12 weeks after contact with the infectious source. If the repeat skin test is positive (> 5 mm), therapy should be continued.

For a patient who has had close contact with a TB positive person and has a positive T-spot, precautions should be taken when they come to the clinic for a chest X-ray.

• The patient should be considered a candidate for preventive therapy with isoniazid, as they have been in close contact with someone with newly diagnosed infectious tuberculosis.
• A chest X-ray should be performed to check for any signs of active tuberculosis or other abnormalities.
• The patient's tuberculin skin test results should be taken into account, and if the result is positive (≥ 5 mm), therapy should be continued.
• The patient should be monitored closely for any signs of active tuberculosis or other complications. 2

From the Research

Precautions for Chest X-ray after Positive T-Spot and Close Contact with TB Positive Person

• When a patient comes to the clinic for a chest X-ray after a positive T-Spot test and close contact with a TB positive person, several precautions should be taken:
  • The patient should be evaluated for latent tuberculosis infection (LTBI) using the interferon-gamma release assay (IGRA) 3, 4
  • The patient's medical history should be obtained, including any history of tuberculosis or close contact with someone with tuberculosis 5, 6
  • The patient should be screened for active tuberculosis using methods such as chest X-ray, sputum smear, and nucleic acid amplification-based tests 7
• The following precautions should be taken during the chest X-ray procedure:
  • The patient should be instructed to wear a mask to prevent the spread of tuberculosis to others 5
  • The X-ray technician should wear personal protective equipment, including a mask and gloves, to prevent exposure to tuberculosis 5
  • The X-ray room should be ventilated to prevent the spread of tuberculosis 5

Diagnostic Value of IGRA-TB

• The diagnostic value of IGRA-TB using the IchromaTM IGRA-TB diagnostic kit has been evaluated in a study, which found:
  • Sensitivity: 80.56% 7
  • Specificity: 85% 7
  • Positive predictive value (PPV): 90.62% 7
  • Negative predictive value (NPV): 70.83% 7
  • Accuracy rate: 82.14% 7

Contact Tracing Investigation

• A contact tracing investigation should be conducted to identify individuals who have been in close contact with the patient, including:
  • Healthcare workers who have come into contact with the patient 5
  • Family members and close contacts of the patient 5
  • Others who have been in close contact with the patient, such as coworkers or classmates 5

Treatment and Prevention

• Individuals who test positive for LTBI should be treated with prophylactic therapy to prevent the development of active tuberculosis 3
• Individuals who have been in close contact with someone with tuberculosis should be screened for LTBI and treated if necessary 5