[Staining of mycobacteria without pre-heating in a modification of the Ziehl-Neelsen method]

To evaluate the use of a new solution for the staining of mycobacteria without pre-heating for microscopic examinations in visible light. To verify the possibilities of the method in everyday practice.

For the diagnostic staining of mycobacteria we used a modification of the Ziehl-Neelsen method without pre-heating. The carbolfuchsin solution contained a higher proportion of basic fuchsin, alcohol and phenol than in the original method; all other solutions used in this method remained unchanged. Efficacy was verified on 8 mycobacterial strains by a comparison with the original procedure that uses pre-heating, as well as with the fluorescence method. 310 microscopic specimens from clinical samples were compared with the fluorescence method, 2 500 smears from cultures were compared with the original staining method.

The results of mycobacteria staining with a modification of the Ziehl-Neelsen method without pre-heating were similar as those obtained by staining with the original method. The sensitivity of the new method was slightly lower than fluorescence (89 % and 92 %), but its specificity was higher (82 % and 65 %).

The method can be used for the staining of mycobacteria in everyday practice. Its efficacy was verified on microscopic specimens from clinical samples and on smears from cultures.