Equivalence of acid alone or acid-alcohol as decolourizing agent in Ziehl-Neelsen method.

Sekar, M Gomathi and Rehman, Fathima and Kumar, Vanaja and Selvakumar, N (2012) Equivalence of acid alone or acid-alcohol as decolourizing agent in Ziehl-Neelsen method. The Indian journal of tuberculosis, 59 (4). pp. 219-23. ISSN 0019-5707

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BACKGROUND Microscopists opine that acid-alcohol decolourized slides may enhance acid-fast bacilli (AFB) smear positivity, and published documents on equivalence of acid and acid-alcohol in ZN staining method are not easily accessible. SETTING National Institute for Research in Tuberculosis, Chennai, India. OBJECTIVE To document the equivalence of 25% sulphuric acid (ZN-acid method) and 3% hydrochloric acid-alcohol (ZN-alcohol method) as decolourizing agents in ZN method for detection of acid-fast bacilli. METHODS Two smears from each of 253 sputum samples from pulmonary tuberculosis patients, prepared and allocated, one to ZN-acid method and another to ZN-alcohol method were read blind. All the specimens were cultured for Mycobacterium tuberculosis by modified Petroff's method. Culture of M. tuberculosis was gold standard. RESULTS The concordance between the methods was 85% (kappa 0.68), and the sensitivity (79%) and specificity (89%) were same for both the methods. CONCLUSION In conclusion, the common belief that acid-alcohol decolourized slides give enhanced smear positivity stands void.

Affiliation: ICMR-National Institute for Research in Tuberculosis
Item Type: Article
Uncontrolled Keywords: AFB, Decolourizing agent, Mycobacterium tuberculosis, Ziehl-Neelsen
Subjects: Tuberculosis > Laboratory Research > Bacteriological
Divisions: Basic Science Research > Bacteriology
Depositing User: Dr. Rathinasabapati R
Date Deposited: 14 Sep 2022 11:32
Last Modified: 14 Sep 2022 11:32
URI: http://eprints.nirt.res.in/id/eprint/1186

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