The laboratory diagnosis of tuberculosis in a period of resurgence: challenge for the laboratory.

OBJECTIVE: To review the current and contemporary approaches to the laboratory diagnosis of Mycobacterium tuberculosis and related mycobacteria. DATA SOURCES: Current literature. STUDY SELECTION: Determined by the author. DATA EXTRACTION: Determined by the author. DATA SYNTHESIS: The definitive diagnosis of mycobacterial disease depends upon the laboratory for the isolation and identification of the infecting microorganism. Laboratory studies encompass microscopic examination for the presence of AFB; isolation and recovery of the organism by cultural methods; phenotypic biochemical or other contemporary means to identify the recovered organism; and anti-tuberculosis susceptibility testing. Because of the extended growth period of this group of organisms, it is imperative that the lab use the most rapid means to provide information to the clinician for isolation of the patient if needed and for the initiation of prompt rational therapy as determined by susceptibility testing. More than 25 species in the Mycobacterium genus are capable of causing human disease. In the United States, the five most frequently encountered species are M. tuberculosis, M. avium, M. kansasii, M. fortuitum and M. chelonei. CONCLUSION: Tuberculosis is a reemerging disease with significant health problem implications in the US and worldwide. Diagnosis and appropriate treatment are dependent on the prompt response of the laboratory.