INFECTION CAUSED BY MYCOBACTERIUM-TUBERCULOSIS

OBJECTIVE: To update readers on the clinical management of infections caused by Mycobacterium tuberculosis, to provide a general description of the organism, culture and susceptibility testing, and clinical man ifestations of the disease, and to provide several aspects of the trea tment of the disease, including historical perspective, current approa ches, and research opportunities for the future. DATA SOURCES: The cur rent medical literature, including abstracts presented at recent inter national meetings, is reviewed. References were identified through MED LINE, MEDLARS II, Current Contents, and published meeting abstracts. S TUDY SELECTION: Data regarding the epidemiology, clinical manifestatio ns, culture and susceptibility testing, and treatment of tuberculosis are cited. Specific attention has been focused on the clinical managem ent of patients with noncontagious infection and potentially contagiou s active disease (TB) caused by M. tuberculosis. DATA EXTRACTION: Info rmation contributing to the discussion of the topics selected by the a uthors is reviewed. Data supporting and disputing specific conclusions are presented. DATA SYNTHESIS: The incidence of TB is increasing in t he US, despite the fact that available technologies are capable of con trolling the vast majority of existing cases. Fueling the fire is the problem of coinfection with HIV and M. tuberculosis. Very few drugs ar e available for the treatment of TB, and few of these approach the pot ency of isoniazid and rifampin. Preventive therapy of patients exposed to multiple-drug-resistant M. tuberculosis (MDR-TB) is controversial and of unknown efficacy. Treatment of active disease caused by MDR-TB requires up to four times longer, is associated with increased toxicit y, and is far less successful than the treatment of drug-susceptible T B. Strategies for the management of such cases are presented. The risi ng incidence of TB in the US reflects a breakdown in the healthcare sy stems responsible for controlling the disease, which reflects the past budgetary reductions. Although TB control is one of the most cost-eff ective public health strategies, funding has been cut repeatedly despi te the fact that TB was never eliminated. This has helped to produce t he current crisis, including the spread of MDR-TB in many urban areas. The elimination of TB will now take decades longer, cost hundreds of millions of dollars more, and result in vastly higher morbidity and mo rtality rates than would have occurred with timely, adequate measures. CONCLUSIONS: Tremendous effort and far more funding will be required to eliminate TB in the US. The selection of drug therapy must be based on the susceptibility data for each isolate. Multiple-drug therapy mu st be continued for 6 to greater-than-or-equal-to 4 months, and patien t adherence to prescribed regimens must be verified in all cases of TB . Significant antimycobacterial drug malabsorption has been documented in AIDS patients with TB, and may result in treatment failure. New ag ents are needed to improve the clinical outcome in patients with MDR-T B.