Improving acid-fast fluorescent staining for the detection of mycobacteria using a new nucleic acid staining approach.

Acid fast staining of sputum smears by microscopy remains the prevalent method for detecting Mycobacterium tuberculosis. The sensitivity of microscopy using acid fast stains requires 104 bacilli per ml of sputum. Although fluorescent acid fast stains, such as Auramine-O, show improved sensitivity, almost half of culture-positive TB cases are currently estimated to remain smear-negative. These current diagnosis problems provide impetus for improving staining procedures.