Evaluation of Different Staining Techniques (Ziehlneelsen Stain, Kinyoun Stain, Modified Cold Stain and Fluorochrome Stain) for the Diagnosis of Pulmonary Tuberculosis

Abstract

Bacteriological examination of sputum is the cornerstone in the diagnosis of pulmonary tuberculosis in the developing world. The risk of spread of infection and emergence of drug resistant strain has created the need of rapid, sensitive and specific diagnostic test. This prospective study was performed in Tuberculosis research laboratory, Department of Microbiology, BPKIHS, Dharan with an objective to evaluate different staining techniques(Ziehl-Neelsen (ZN), Kinyoun, Modified cold (MC), and Fluorochrome) for detection of acidfast bacilli (AFB) for diagnosis of pulmonary tuberculosis The study was cross-sectional study. All the samples were processed by modified Petroff’s method. From each sample four smears were prepared and were stained with four different staining techniques: ZN, Kinyoun, MC, and Fluorochrome respectively. Culture was employed as gold standard for tuberculosis diagnosis. A total of 1365 specimens from 500 patients were analyzed. 109 patients (21.8%) were diagnosed as having TB by culture. The positive yieldfound with the staining techniques were 14.2% by ZN, 13.8% by Kinyoun, 14.4% by MC and 17.6% by Fluorochrome staining methods. With reference to culture, sensitivity of ZN, Kinyoun, MC and Fluoro chrome were found to be 57.8%, 56%, 59.6%, and 71.6% respectively. Thespecificity in ZN, Kinyoun and Fluorochrome methods was 98% and that in MC was 98.2%. The positive predictive value of ZN, Kinyoun, MC,Fluorochrome was found to be 88.7%, 88.4%, 90.3% and 90.7% and the negative predictive value of ZN, Kinyoun, MC, Fluorochrome was found to be 89.3%, 88.9%, 89.7% and 92.5% respectively. This study indicates that the Fluorescent staining method was found most reliable out of theother staining techniques. The MC method also could be viable alternative to ZN and Kinyoun for primary diagnosis of tuberculosis. Keywords:M. tuberculosis, Ziehl-Neelsen, Kinyoun, Modified cold, Fluorochrome stain