Tuberculosis (TB) is a chronic bacterial infection spread from human to human through respiratory droplets containing M tuberculosis, an acid-fast bacillus. Upon inhalation, the organisms are transported to regional lymph nodes where the immune system forms granulomas or “tubercles.” Most people undergo complete healing following exposure with only a positive purified protein derivative (PPD) test. However, it may lie dormant as latent disease until the immune system is suppressed, leading to organism release. TB occurs worldwide but is more common in impoverished nations.
The organisms are dependent on high oxygen content and are typically found in the upper lobe or superior segment of the lower lobes of the lungs. Although it is primarily a respiratory illness, 15% will exhibit extrapulmonary manifestations involving the adrenal glands, long bones, vertebrae, GI tract, GU tract, skin, lymph nodes, meninges, pericardium, or peritoneum. Patients with HIV infection have a much higher overall prevalence and rate of extrapulmonary disease. Common symptoms of active TB are fever, night sweats, malaise, weight loss, cough, hemoptysis, and pleuritic chest pain. Diagnosis is made by the PPD and chest x-ray but is confirmed through acid-fast bacillus (AFB) smears and sputum culture. The mainstay of diagnosis in resource-limited countries is the AFB smear.
Tuberculosis Adenopathy. Bilateral cervical adenopathy (scrofula) in a Peruvian child with documented TB. Pediatric cervical adenopathy in highly endemic areas is strongly suggestive, and the most common form, of extrapulmonary TB. (Photo contributors: Seth W. Wright, MD, and Universidad Peruana Cayetano Heredia, Lima, Peru.)
Tuberculosis Scarring. Chronic discharging sinuses with extensive scar formation in a Peruvian man with extrapulmonary tuberculosis. (Photo contributors: Seth W. Wright, MD, and Universidad Peruana Cayetano Heredia, Lima, Peru.)
Tuberculosis Cold Abscess. Cold abscess on the back of a Haitian woman with untreated Pott disease. (Photo contributor: Seth W. Wright, MD.)
Tuberculosis Pott Disease. Severe spinal deformity (“gibbus”) in an 8-year-old Ugandan boy with Pott disease. (Photo contributor: Seth W. Wright, MD.)
Management and Disposition
Typical first-line chemotherapy consists of isoniazid, rifampin, pyrazinamide, and ethambutol for 2 months, followed by isoniazid and rifampin for 4 months. Patients in developed countries are usually admitted with respiratory isolation. Outpatient therapy is common in developing countries. After 2 weeks of treatment, the patient is usually no longer contagious. Poor long-term adherence is a major contributing factor to the development of multidrug-resistant strains. Directly observed therapy (DOT) where patients are observed taking the medication may be required to ensure compliance and is routine in most countries.