Comparative Study Of Conventional Smears And Bleach Concentration Method In Detection Of Tubercle Bacilli In Fine Needle Aspiration Material Of Lymph Nodes

Abstract

Background & Objectives: The conventional Ziehl-Neelsen staining method for acid-fast bacilli (AFB) plays a key role in the diagnosis of tuberculosis by direct microscopy. Its major disadvantage is low sensitivity. The present study was performed to emphasize the role of bleach concentration method over conventional direct smear microscopy for detection of tubercle bacilli (AFB) in fine needle aspiration material of lymph nodes. Methods: Fine needle aspirations (FNA) were done in 109 patients with clinical suspicion of tubercular lymphadenitis. Smears from the aspirates were processed for routine cytology and the conventional Z-N method. The remaining material in the needle hub and/or the syringe was used for the bleach method. The significance of the bleach method over the conventional Z-N method and cytology was analyzed. Results: Among the 109 aspirates 35.78% were positive for AFB on conventional Z N method, 43.12% were indicative of TB on cytology and the smear positivity for AFB increased to 62.38% on bleach method. Interpretation and Conclusion: The bleach method is simple, inexpensive and limits the risk of laboratory-acquired infections. The bleach method improves the microscopic detection of AFB and can be a useful contribution to routine cytology.