Bleached smear microscopy provides higher yield in diagnosing pulmonary tuberculosis

Jithendra Kandati, Suresh Kumar Boorsu, Ramamohan Pathalapati, Madhavulu Buchineni


Background: Tuberculosis (TB) remains one of the major deadliest communicable diseases throughout the world. Worldwide, 9.6 million people are estimated to have fallen ill with TB in 2014, India accounts for 23% of total global cases. The study evaluated the performance of direct sputum smear versus bleach concentration smear in diagnosis of pulmonary tuberculosis.

Methods: Patients more than 10 years of age who presented with history of cough for >2 weeks duration were included. One spot specimen and another early morning specimen were collected on two consecutive days. All the sputum smears prepared from direct and bleach concentration were examined under microscope after Ziehl-Neelsen staining.

Results: A total of 290 specimens were examined by microscopy, among which 128/290 (44.1%) were positive on direct smear, additionally 72/290 (24.8%) were positive on bleached smear, and therefore the gain% in the diagnostic yield was 24.8% (P<0.0001). The order of yield was mucoid specimen (28.6%)>blood stained (26.74%) >purulent specimen (20.8%) (p>0.05) and early morning specimens (33%)>spot specimen (22%) (p>0.05), However, these findings were not statistically significant.

Conclusion: Microscopic examination of bleached smear examination has shown a significant yield over conventional method in the detection of pulmonary Tuberculosis. Such superiority was independent of type of sputum and timing of collection of sputum.


Bleach concentration microscopy, Pulmonary tuberculosis, Direct microscopy, Diagnostic yield

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