Acridine orange stain of Mycobacterium leprae

Kim, Jong Pill; Lee, Min Seok; Kang, Jeoung Won

Abstract

The Ziehl-Neelson's AFB staining method was mainly used for the AFB observation of the diagnosis of leprosy. However, the fluorescent stain performs better and allows the detection of more positive smears. The limitation for its widespread use has been the high cost for fluorescent microscopes. Novel light-emitting diodes (LED) are inexpensive solutions for fluorescent microscopes, and thus fluorescent stain may be a cost-effective step to improve the diagnosis of leprosy in resource-poor countries. And the comparison of auramine and acridine orange for staining of acid-fast bacteria was showed significantly more acid-fast rods after using acridine orange and the number of "false positive" results was somewhat higher on auramine staining. So acridine orange offers a good alternative to auramine which is considered carcinogenic. This study evaluated the comparison of the Ziehl-Neelson's AFB stain and the acridine orange stain in the skin smear based on PCR. As PCR results were taken as gold standard, results of the study revealed that the sensitivity of Ziehl-Neelson's AFB stain was 50% and that of acridine orange stain was 92.2%. This study confirmed that the fluorescence stain method is more sensitive than the Ziehl-Neelsen's staining method. It is suggested that the training of laboratory technicians on fluorescence microscopy should be scaled up for increased disease control.