Guide for Primary Health Care Providers: Targeted Tuberculin Testing and Treatment of Latent Tuberculosis Infection 2005

TABLE 1:
Changes Found in the 2000 Guidelines and Subsequent Updates

Testing for LTBI

• Tuberculin skin testing discouraged for those at low risk for developing TB disease
• Testing recommended for high-risk individuals, regardless of age
• Lower cut-off point established for organ transplant recipients and other immunosuppressed persons (on daily prednisone for one or more months); 5 mm induration considered positive
• TST conversion considered an increase in induration of at least 10 mm within a 2-year period, regardless of age
• The QuantiFERON^®-TB test and QuantiFERON^®-TB Gold test (QFT) are blood tests that measures a person’s immune reactivity to M. tuberculosis
• Prolonged use of immunosuppressive agents such as TNF-α antagonists increases risk of progression from LTBI to TB disease

Treatment of LTBI

• INH for 9 months preferred over 6-month regimen for HIV-negative individuals
• INH for 9 months for HIV-infected persons or those with old TB (fibrotic lesions on chest radiograph)
• RIF for 4 months for HIV-uninfected and HIV-infected individuals
• RIF and PZA for 2 months should generally not be offered due to risk of severe adverse events

Clinical and laboratory monitoring

• Baseline and laboratory monitoring needed for HIV-infected persons, pregnant or postpartum women, and persons who have chronic liver disease or who regularly use alcohol
• Follow-up only indicated if baseline tests are abnormal
• Tests include serum AST, ALT, and bilirubin
• Emphasis on clinical monitoring for signs of possible adverse drug reactions

Key: INH – Isoniazid RIF – Rifampin PZA – Pyrazinamide