Acridine orange staining of smears for demonstration of Mycobacterium tuberculosis.

Acridine orange staining for the detection of mycobacteria was compared with staining by auramine O and with mycobacterial culture in a series of 1071 clinical specimens. A total of 78 (7%) specimens were positive by staining. No false positive or negative findings were recorded by the acridine orange method. The two fluorochromes proved equal in their ability to detect mycobacteria in specimens from culture positive cases of tuberculosis. In the rapid bacteriological diagnosis of tuberculosis, acridine orange offers a good alternative to auramine O which is considered carcinogenic.