The laboratory diagnosis of mycobacterial diseases. Challenges and common sense.

The laboratory diagnosis of mycobacterial diseases is reviewed. It is re-emphasized that the diagnosis of mycobacterial diseases, especially tuberculosis (TB), is primarily clinical. With proper collection techniques and an appropriate number of sputa specimens acid-fast smears of concentrated sputa can still result in the detection of the majority of patients with cavitary TB who are responsible for the majority of TB transmission. Finally, the techniques used in the laboratory to diagnose mycobacterial diseases should be matched to the resources available to the laboratory and the incidence of those diseases in the area served by the laboratory.