A technically simple method for staining of acid-fast bacilli in cytology smears: An evaluation


Dr Sujata Chaturvedi, Institute of Human Behaviour and Allied Sciences, PO Box 9520, Jhilmil, Delhi 110 095, India. Email: cvsujata@hotmail.com or cvsanjay@hotmail.com


Objective:  To study the effects of modifications in the Ziehl-Neelsen staining procedure on predictive accuracy for acid fast bacilli in comparison to the conventional technique. Simplicity of procedure and reagent economy were the factors taken into consideration.

Design:  Comparative evaluation between thick and thin air-dried smears stained conventionally and thick ethanol-fixed smears stained by the modified technique was done.

Results:  Positive predictive accuracy of all the three smears, that is, thick air-dried, thin air-dried and thick ethanol-fixed, was 100%. Negative predictive accuracy for thick air-dried, thin air-dried and thick ethanol-fixed smears was 36.36%, 32.33% and 34.78%, respectively. Overall predictive accuracy was 66.67% for thick air-dried, 61.90% for thin air-dried and 64.29% for thick ethanol-fixed. These differences were found to be statistically insignificant.

Conclusion:  The modified method offers an accuracy comparable to the conventional technique, is simpler and with improved reagent economy. It is of special importance to diagnostic facilities in rural set-ups.