Staining techniques for detection of acid fast bacilli: what hope does fluorescein-diacetate (FDA) vitality staining technique represent for the monitoring of tuberculosis treatment in resource limited settings

Despite the recent development of more sensitive technologies, diagnosis of tuberculosis in resource limited settings continues to rely on sputum smear microscopy. This is explained by the fact that smear microscopy is simple, inexpensive, and the most accessible tool in resource limited settings for tuberculosis diagnosis. Hot Ziehl-Neelsen (Z-N) is still used in laboratories of resource limited settings with bright field microscopy. Cold staining methods which use bright field microscopy are now declared obsolete. Currently in most laboratories, methods of staining using fluorescence microscopy (FM) and Light-emitting diodes (LED) microscopy for Acid Fast Bacilli (AFB) are used. Despite the accessibility of Z-N method, only 15 of the 22 high tuberculosis burden countries met the target of having one microscopy centre per 100, 000 persons in 2011. This review attempts to provide an overview description of microscopy methods as well as the Fluorescein-diacetate (FDA) vitality staining methods as alternative for culture and tuberculosis treatment control in resource limited countries.