What are the current guidelines for screening for active tuberculosis (TB) in individuals with known exposure after completing prophylaxis?

From the Guidelines

After completing prophylaxis for tuberculosis (TB) exposure, individuals generally do not require routine screening for active TB unless they develop symptoms, as the primary purpose of TB prophylaxis is to prevent progression to active disease. Once a complete prophylactic regimen has been successfully completed, the risk of developing active TB is significantly reduced, as noted in the guidelines for preventing the transmission of Mycobacterium tuberculosis in health-care facilities 1.

Key Considerations

• Patients should be educated about TB symptoms including persistent cough, fever, night sweats, weight loss, and hemoptysis, and advised to seek medical attention if these develop.
• Individuals with compromised immune systems, such as those with HIV, organ transplants, or on immunosuppressive medications, may benefit from more vigilant monitoring with periodic clinical evaluations, as suggested by the management of latent Mycobacterium tuberculosis infection guidelines for low tuberculosis burden countries 1.
• The World Health Organization recommends systematic testing and treatment of latent TB infection in high-risk individuals, including those with HIV, adult and child contacts of pulmonary TB cases, and patients initiating anti-tumor necrosis factor treatment 1.

Screening Strategies

• The performance of different screening strategies to rule out active TB before latent TB infection treatment has been evaluated, with results indicating that any abnormality on chest radiograph (CXR) plus presence of any TB symptom has a high sensitivity and specificity 1.
• However, routine screening for active TB is not necessary in asymptomatic individuals who have completed appropriate preventive therapy, unless they develop symptoms or have compromised immune systems.

Evidence-Based Recommendations

• The guidelines for preventing the transmission of Mycobacterium tuberculosis in health-care facilities recommend establishing a TB counseling, screening, and prevention program for health-care workers 1.
• The management of latent Mycobacterium tuberculosis infection guidelines for low tuberculosis burden countries provide recommendations for systematic testing and treatment of latent TB infection in high-risk individuals 1.
• The European Respiratory Journal study on the management of latent Mycobacterium tuberculosis infection provides evidence-based guidelines for the management of latent TB infection in high-risk individuals 1.

From the FDA Drug Label

Isoniazid is recommended as preventive therapy for the following groups, regardless of age. 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 current guidelines for screening for active tuberculosis (TB) in individuals with known exposure after completing prophylaxis are:

• Close contacts of persons with newly diagnosed infectious tuberculosis should be screened with a tuberculin skin test (≥ 5 mm) 2
• Tuberculin-negative children and adolescents who have been close contacts of infectious persons within the past 3 months should have a repeat tuberculin skin test done 12 weeks after contact with the infectious source 2
• If the repeat skin test is positive (> 5 mm), therapy should be continued 2
• No specific guidelines are provided for screening for active TB after completing prophylaxis in individuals with known exposure, other than the above recommendations for close contacts and tuberculin-negative individuals 2

From the Research

Screening for Active TB after Prophylaxis

• The current guidelines for screening for active tuberculosis (TB) in individuals with known exposure after completing prophylaxis involve testing individuals at increased risk of latent TB infection (LTBI) with an interferon-gamma release assay or tuberculin skin testing, as recommended by the U.S. Preventive Services Task Force 3.
• Individuals with symptoms of TB disease warrant testing, and chest radiography should be performed after a positive test result 3.
• The use of GeneXpert MTB/RIF assay has been found to be a rapid and accurate tool for MTB detection in smear-negative sputum specimens, detecting MTB and rifampicin resistance simultaneously within 2 hours with minimal biohazards 4.
• Early chest X-ray in persons with presumptive tuberculosis increases Xpert MTB/RIF diagnostic yield and efficiency, and using CXR to triage for culture or Xpert testing reduces the number of missed cases and increases the efficiency of culture and Xpert testing 5.

Diagnostic Methods

• Sputum smear microscopy and Xpert MTB/RIF assay are both useful diagnostic methods for pulmonary tuberculosis, but neither provides all the information needed for diagnosis and treatment monitoring on its own 6.
• GeneXpert has been found to be superior to smear microscopy and comparable to culture, with a shorter turnaround time, and is recommended for use in routine TB diagnosis to expedite patient management 7.
• The sensitivity, specificity, positive predictive value, and negative predictive value of GeneXpert in diagnosis and detection of rifampicin resistance in pulmonary and extrapulmonary TB cases have been found to be high, making it a valuable tool in TB diagnosis 7.

Treatment and Reporting

• Preferred treatment regimens for LTBI include isoniazid in combination with rifapentine or rifampin, or rifampin alone for a duration of three and four months, respectively 3.
• Treatment of drug-susceptible TB disease includes an eight-week intensive phase with four drugs, followed by a continuation phase lasting 18 weeks or more, with two drugs based on susceptibility testing results 3.
• Both suspected and confirmed cases of LTBI and TB disease must be reported to local or state health departments 3.