Comparative efficacies of three acid-fast staining techniques under field conditions for Mycobacterium tuberculosis in the Indian context

Abstract

Tuberculosis is a most important human disease in its global prevalence. It is caused by tubercle bacilli. Among the various methods for diagnosis of pulmonary tuberculosis, bacteriological methods are more important. Standard Ziehl-Neelsen method of staining is most reliable for this. But due to some operational disadvantages in the Ziehl-Neelsen method, many other methods were also discovered. In this research work two such techniques that is Modified Ziehl-Neelsen method where a boiling water bath is used as a source of heating and cold staining method where heating is completely eliminated and instead of which duration of exposure to carbol-fuchsin stain prolonged to 10 minutes were compared with conventional Ziehl-Neelsen method. For these 145 sputum samples having the symptoms of tuberculosis were collected and each of these samples were stained by three above mentioned methods. The results were analyzed by Mc Nemar’s chi-square test and kappa statistics. It was observed that Cold-staining method is more appropriate than that of the Modified Ziehl-Neelsen method. Additionally due to some advantages in cold staining method it is more reliable and safer than that of the standard Ziehl-Neelsen method in field conditions.