What is the next step in evaluation for a patient with a positive T-SPOT (T-cell spot test) after contact with a confirmed tuberculosis patient, who remains asymptomatic?

From the Guidelines

For a patient with a positive T-SPOT.TB test after contact with a confirmed tuberculosis case who is currently asymptomatic, the next step is to obtain a chest X-ray to rule out active tuberculosis disease. If the chest X-ray is normal, the patient should be diagnosed with latent tuberculosis infection (LTBI) and offered treatment. The recommended regimen is 3 months of once-weekly isoniazid 900 mg plus rifapentine 900 mg (3HP), or alternatively, 4 months of daily rifampin 600 mg (4R), or 9 months of daily isoniazid 300 mg (9H) 1. For the 3HP regimen, directly observed therapy is preferred. Before starting treatment, baseline liver function tests should be obtained, especially for patients with risk factors for hepatotoxicity. Monthly clinical monitoring for adverse effects is recommended during treatment, with additional liver function testing for those with baseline abnormalities or risk factors. Treatment of LTBI is important because it reduces the risk of progression to active TB disease by 60-90%, and recent contacts are at highest risk for progression within the first two years after infection. Key considerations in the management of LTBI include:

• The use of a single regimen, such as 3HP, which has been shown to be effective in preventing the progression to active TB disease 1
• The importance of directly observed therapy to ensure adherence to the treatment regimen
• The need for regular monitoring of liver function tests to minimize the risk of hepatotoxicity
• The consideration of risk factors for hepatotoxicity, such as age, liver disease, and concomitant use of other medications. It is also important to note that the patient should be advised that they can be re-infected with M. tuberculosis if re-exposed, and that treatment of LTBI does not provide immunity to future infections 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.

The next step in evaluation for a patient with a positive T-spot after contact with a confirmed tuberculosis patient, who is asymptomatic, is to consider preventive therapy since the patient is a close contact of a person with newly diagnosed infectious tuberculosis. The patient should undergo further evaluation to determine the appropriate course of treatment, which may include isoniazid preventive therapy for at least 12 months, as recommended for close contacts with a positive tuberculin skin test reaction of ≥ 5 mm 2.

From the Research

Next Steps in Evaluation

• The patient has tested positive for TB infection after contact with a confirmed tuberculosis patient and is asymptomatic.
• The next step in evaluation would be to assess the patient's risk factors for developing active tuberculosis disease, such as age, immune status, and presence of any underlying medical conditions 3, 4.

Treatment Options

• Treatment of latent tuberculosis infection (LTBI) is an important component of TB control and elimination.
• Several treatment regimens are available, including:
  • Once-weekly isoniazid plus rifapentine for 3 months
  • Daily rifampin for 4 months
  • Daily isoniazid plus rifampin for 3-4 months
  • Daily isoniazid for 6-9 months 3, 4, 5, 6, 7

Treatment Completion and Safety

• Treatment completion rates vary among different regimens, with 3 months of isoniazid and rifapentine having higher completion rates compared to 9 months of isoniazid 5, 6.
• The risk of hepatotoxicity is lower with rifampin compared to isoniazid, and treatment completion is higher with rifampin 7.
• The choice of treatment regimen should be individualized based on the patient's risk factors, medical history, and preferences 3, 4, 5, 6, 7