Diagnosis and Detection of Drug-Resistant Strains of M. tuberculosis

Abstract

Although tuberculosis (TB) continues to affect an estimated 10% to 50% of the world population, with three million tuberculosis-related deaths annually, the disease had been widely believed to be controlled in the United States. Improved nutrition, higher standards of living for the poor, and the post-World War II discoveries of antituberculosis antibiotics dramatically decreased the incidence of active disease. The rate of decline in incidence in the U.S. had been approximately 6% per year, reaching an all-time low of only 22,000 reported cases in 1984.1,2 This decline in diagnosed disease was the foundation for the forecast that complete eradication of tuberculosis could be achieved in the United States by the end of the 20th century. However, beginning in the 1960s, responsibility for managing remaining tuberculosis cases shifted from specialized hospital units to less-well-equipped outpatient settings. Medical school teaching of tuberculosis-related issues declined, and research funding for the disease was dramatically reduced.2 In the 1980s, large-scale immigration from regions endemic for tuberculosis introduced new cases into the U.S., and the increase in homelessness and AIDS in American cities has created a dangerous and self-perpetuating pocket of disease in two populations that are particularly at risk. Finally, the ease with which the organism can spread within institutionalized populations has made outbreaks of tuberculosis common in prisons, nursing homes, and hospitals. As a result of these many factors, a deadly resurgence of this ancient scourge is taking place, with an estimated 10 to 15 million Americans currently infected by tuberculosis.1 Two recent studies from San Francisco and New York revealed startling findings about the nature of the latest epidemic.3,4 Using DNA fingerprinting to evaluate the relative contribution of recent infection to the overall incidence of TB, these studies found that at least 33% of current cases can …