needs for tuberculosis diagnosis, treatment, and prevention, the dynamics that influence research efforts, and the ongoing activities of the key groups involved. It also identifies the research efforts needed to accelerate the decline in cases and the move toward the elimination of tuberculosis.
Currently, the management of tuberculosis is dependent on the ability to identify individuals with active disease, those whose disease is caused by organisms resistant to antimicrobial agents, those who are infected but not ill, and those who are most likely to progress from infection to disease. Although precise numbers are not known, the World Health Organization (WHO) (Mark Perkins, personal communication) estimates that each year sputum examiners screen approximately 60 million to 80 million people for active tuberculosis and that multiple examinations are conducted for each of these people. However, even gross estimates of the number of tuberculin skin tests, for acid-fast bacilli (AFB) smears, radiographs, cultures, or other tests are not available. Although great strides have been made in decreasing the burden of tuberculosis in the United States by using existing technologies, there is considerable room for improvement in each of these endeavors, particularly in children, human immunodeficiency virus (HIV)-infected individuals, and the increasing numbers of patients with tuberculosis outside of their lungs.
The microscopic examination of sputa for the detection of AFB (AFB smear) is rapid, technically simple, and widely available and identifies those thought to be most infectious to others. However, WHO estimates that AFB is identified by sputum microscopy in only 35 percent of people with active tuberculosis (Raviglione et al., 1997). Furthermore, a molecular epidemiological approach has demonstrated that even in efficiently administered tuberculosis control programs, those persons who are AFB smear negative account for at least 15 percent of cases of disease transmission (Behr et al., 1999). Laboratory techniques for the replacement or improvement of the detection of AFB in clinical specimens that address these limitations would greatly enhance patient care and infection control.
Cultivation of mycobacteria from specimens obtained from persons suspected of having tuberculosis remains the mainstay for the diagnosis of tuberculosis and the identification of bacterial strains that are resistant to antibiotics. The use of rapid radiometric techniques has greatly decreased the time required for cultivation and susceptibility testing of mycobacteria, and the use of DNA probes can speed the identification of