Recommended Preventive Treatment Regimens for TB in High-Risk Groups and Close Contacts
For high-risk groups and close contacts of individuals with active tuberculosis, the recommended preventive treatment regimen is 9 months of daily isoniazid, with alternative options including 4 months of daily rifampin, 3 months of daily isoniazid plus rifampin, or the newer 12-dose regimen of once-weekly isoniazid plus rifapentine. 1, 2
Identification of High-Risk Groups Requiring Preventive Treatment
High-risk groups who should be tested and treated for latent TB infection include:
- Close contacts of persons with infectious TB (≥5mm induration on TST) 1, 2
- HIV-infected individuals (≥5mm induration on TST) 1
- Persons initiating anti-TNF treatment 1
- Patients receiving dialysis 1
- Patients preparing for organ or hematological transplantation 1
- Persons with silicosis 1, 2
- Children under 5 years of age who are close contacts 1, 3
- Persons with fibrotic lesions on chest radiographs 2
- Persons with medical conditions increasing TB risk (diabetes mellitus, prolonged corticosteroid therapy, immunosuppressive therapy) 2
Diagnostic Evaluation Before Starting Treatment
Before initiating preventive treatment:
Rule out active TB disease through:
- Clinical evaluation
- Chest radiography
- Sputum collection when indicated 1
Test for latent TB infection using:
Recommended Preventive Treatment Regimens
First-line regimens:
- 9 months of daily isoniazid (AII) 1, 2
- Add pyridoxine (vitamin B6) to prevent peripheral neuropathy
- Can also be administered twice weekly under directly observed therapy (DOT)
Alternative regimens:
- 4 months of daily rifampin (BIII) 1, 4
- 3 months of daily isoniazid plus rifampin (BI) 1, 5
- 12 doses of once-weekly isoniazid plus rifapentine (newer regimen) 5, 6
Special Considerations for Drug-Resistant TB Contacts
For contacts of drug-resistant TB patients:
- For isoniazid-resistant TB: 4 months of daily rifampin 1
- For MDR-TB (resistant to both isoniazid and rifampin):
- Consult with TB experts for individualized regimens
- Consider drug susceptibility results of the index case
- Close monitoring for 2 years after exposure 1
Treatment Prioritization and Monitoring
Priority groups for directly observed therapy (DOT):
- Contacts aged <5 years
- HIV-infected or immunocompromised contacts
- Contacts with TST conversion from negative to positive
- Contacts with social or behavioral factors affecting adherence 1
Monitoring recommendations:
- Monthly in-person evaluation by healthcare provider
- Assessment for adherence and adverse effects
- Liver function monitoring, especially for older patients
- Education about TB, treatment, and adverse effects 1
Treatment Completion Goals
The target completion rate for preventive treatment is 85% 1. To improve adherence:
- Use incentives (e.g., food coupons)
- Provide enablers (e.g., transportation vouchers)
- Consider DOT for high-risk groups 1
Common Pitfalls and Caveats
Drug interactions: Rifampin and rifabutin can interact with HIV medications, particularly protease inhibitors and NNRTIs. Carefully evaluate potential drug interactions before selecting a regimen 1
Window period prophylaxis: For vulnerable contacts with initial negative TST/IGRA, consider prophylaxis until repeat testing at 8-12 weeks, particularly for children <5 years and immunocompromised individuals 1
Hepatotoxicity risk: Weigh the risk of hepatitis against the risk of TB, particularly in patients >35 years old 2
Contraindication: BCG vaccination is contraindicated in HIV-infected persons due to risk of disseminated disease 1
By implementing these evidence-based preventive treatment strategies, the risk of TB disease development among high-risk contacts can be reduced by up to 90% 5, significantly contributing to TB control and elimination efforts.