[Utility of the Rapid Staining with the Use of Microwave for Detection of Genus Mycobacterium]

Abstract

Recently, many laboratories use fluorescence microscopy for rapid screening of clinical specimens for detection of Genus Mycobacterium. The success of the stain depends on the staining temperature at which the fluorescent dye could uniformly penetrate the cell wall through waxy lipid barrier of the mycobacterial organism. Therefore, this process requires a precise heating control. In this study, to control the temperature during fluorescent auramine- rhodamine staining, we explored the potential use of microwave. The efficiency of microwave irradiation during the staining process was evaluated by using a Mycobacterium avium-containing sputum of which the smear slide was irradiated with several different conditions in combination of time and wattage. As a result, 1) the liquid temperature of the stain correlated well with wattage of microwave irradiation. 2) The tubercle bacilli were easily visualized as brilliant fluorescent bacilli in an orange color when it was set at the best condition of 600 W and 10 sec irradiation. 3) The sensitivity of microscopy with this staining method (MW method) was higher than those of conventional staining methods such as Ziehl-Neelsen staining and standard auramine-rhodamine staining, demonstrating that MW method can be applicable to the sputum slides which contained a few bacilli. Thus, we established the new staining method that is rapid and easy to perform in clinical laboratories. Since the MW method has not yet been utilized in order to conduct fluorescence microscopy for sputum smears, advancement on this method will make a vast change in testing of acid fast bacilli.