PURPOSE: Sputum microscopy by Ziehl-Neelsen stain (Z-N stain) is the most efficient method for diagnosis of pulmonary tuberculosis and forms the cornerstone of Revised National Tuberculosis Control Program (RNTCP). Various efforts have been made to make this method simpler, efficient and cost effective. 2-reagent cold staining method is one such modification which has been scarcely evaluated. The present study was conducted to assess the usefulness of 2-reagent cold staining method in the detection of acid fast bacilli and hence its applicability in field conditions like peripheral health institutions.
METHODS: Total 100 cases of fresh pulmonary tuberculosis were included. Sputum of each patient was stained by Ziehl-Neelsen staining method, conventional cold stain and 2-reagent cold staining method and was also subjected to culture in Lowenstein-Jensen media. The results were evaluated for sensitivity, specificity and degree of agreement keeping culture as the gold standard.
RESULTS: The sensitivity, specificity and efficiency of the 2-reagent cold staining method were 79.22%, 82.6% and 80% while that of Z-N staining method were 80.51%, 78.26% and 80% respectively. The overall degree of agreement between the two methods was 98%. The conventional cold staining method, on the other hand, gave inferior results as compared to the other two methods.
CONCLUSION: 2-reagent cold staining method is a superior staining method as compared to Ziehl-Neelsen staining method as, not only it gave results comparable to Z-N staining but also it had advantages of being easier to perform, without the need of alcohol (hence cost effective) and requiring less time.
CLINICAL IMPLICATIONS: 2-reagent cold staining method may be better suited for use in resource poor, peripheral health institutions than Z-N staining method for the diagnosis of pulmonary tuberculosis. Further studies are needed to evaluate it under program conditions.
DISCLOSURE: Deepak Aggarwal, No Financial Disclosure Information; No Product/Research Disclosure Information