In the United States, the epidemiology of tuberculosis (TB) has changed in recent years. Infection by human immunodeficiency virus (HIV) and the increase in homelessness, poverty, and drug abuse are major factors in this change. Tuberculosis occurs most commonly among ethnic minorities, African Americans, and Hispanics 25 to 44 years of age. Immigrants from developing countries with a high prevalence of TB and drug resistance have contracted almost one half of the new cases in this country for the past several years. Drug-resistant disease is a major concern.

DIAGNOSIS

The chest x-ray is frequently suggestive of TB (Figure 155.1). Whenever there is a suspicion of pulmonary TB, three spontaneously produced sputum specimens should be examined by microscopy and culture. If necessary, sputum production may be induced by inhalation of aerosol of warm saline (Figure 155.2). Methods such as early-morning gastric lavage and laryngeal swab on suction are less productive. When suspicion of TB is high and microscopy is negative on at least three specimens, a bronchial washing or transbronchial biopsy through a fiberoptic bronchoscope or postbronchoscopy sputum may be productive. In an unconscious patient, tracheal aspiration or transthoracic needle aspiration of the lung may be needed to obtain a specimen. On rare occasions diagnosis must be made by open lung biopsy.