Respiratory infections: pulmonary tuberculosis

Family physicians can prevent mortality and disability due to pulmonary tuberculosis (TB) by identifying high-risk patients. Recognition of symptoms (eg, cough for 3 weeks or longer) helps prevent overlooked diagnoses because results of tuberculin skin tests and interferon-gamma release assays are negative in up to 25% and 21%, respectively, of severe acute cases. The typical x-ray findings of cavities, infiltrates, and lymphadenopathy are minimal among immunosuppressed patients. Cases of active TB must be reported to local or state health departments within 24 hours of diagnosis. Sputum acid-fast bacillus tests provide results within hours and help quantify bacterial load but are not highly sensitive, and infection with nontuberculous mycobacteria can cause positive test results. Sputum cultures are adequately sensitive, identify mycobacterial species, and provide organisms for antibiotic susceptibility testing but require weeks for results. Molecular detection of Mycobacterium tuberculosis and of antibiotic-resistant mutations can expedite diagnosis and management of drug-resistant TB. Management of active TB should include directly observed therapy. Standard 6-month therapy with rifampin, isoniazid, pyrazinamide, and ethambutol resolves infection in nearly all immunocompetent adults with pansensitive TB. Multidrug-resistant TB requires second-line antibiotics (eg, fluoroquinolones, linezolid) in individualized regimens lasting 2 years. Management of latent TB infection prevents progression to active TB disease, particularly if management is completed within 2 years of infection.