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PATIENT STORY

A 20-year-old man presents to the emergency department with a persistent cough for 3 weeks, low-grade fever, and night sweats. His chest X-ray shows mediastinal and right hilar lymphadenopathy and right upper lobe consolidation concerning for primary tuberculosis (Figure 56-1). Upon review of the radiograph, the emergency room staff admits the patient to a single room with negative pressure. The patient is placed in respiratory isolation, sputum is sent for acid-fast bacillus (AFB) stain and cultures, and the results show acid-fast bacilli consistent with Mycobacterium spp. (Figure 56-2). While culture results are pending, the patient is started on four antituberculosis drugs. Fortunately, the sputum culture result shows pansusceptible Mycobacterium tuberculosis, and his treatment continues with directly observed therapy through the local city health department.

FIGURE 56-1

Typical presentation of a primary pulmonary tuberculosis infection in a 20-year-old man. A. Frontal chest radiograph shows mediastinal and right hilar lymphadenopathy (black arrows) and right upper lobe consolidation (white arrow). B. Contrast-enhanced CT demonstrates low-density enlarged mediastinal lymph nodes with rim peripheral enhancement consistent with necrotizing lymphadenopathy (arrows). (Reproduced with permission from Carlos Santiago Restrepo, MD.)

FIGURE 56-2

The acid-fast bacilli of Mycobacterium tuberculosis seen with acid-fast staining at 100 power with oil immersion microscopy. (Reproduced with permission from Richard P. Usatine, MD.)

INTRODUCTION

Tuberculosis (TB) is a bacterial infection caused by M. tuberculosis, an obligate intracellular pathogen that is aerobic, acid fast, and nonencapsulated. TB primarily involves the lungs, although other organs are involved in one-third of cases. Improvements in diagnostics, drugs, vaccines, and understanding of biomarkers of disease activity are expected to change future management of this devastating worldwide disease.

EPIDEMIOLOGY

  • Among individuals who were HIV-negative, all-form TB incidence worldwide in 2013 was 7.1 million (6.9 million to 7.3 million), prevalence was 11.2 million (10.8 million to 11.6 million), and number of TB-related deaths was 1.3 million (1.2 million to 1.4 million).1

  • A total of 9557 TB cases (3.0 per 100,000 persons) were reported in the United States in 2015; the incidence has been relatively stable since 2013.2 The highest incidence rates were recorded in California, Georgia, New York, and Texas.

  • The multidrug-resistant (MDR) TB rate in the United States was 1.2% (88 cases) in 2010, a rate that remains relatively stable in the United States.1 MDR TB rates are highest in India, China, the Russian Federation, South Africa, and Bangladesh.3 Global incidence of MDR TB in children was estimated at 3.2%4; isoniazid-resistant TB in children was estimated at 12.1% in 2010, with the ...

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