Indian Journal of Microbiology Research


Different Methods of Staining to optimize Smear Microscopy for Diagnosis of Pulmonary and Extra Pulmonary Tuberculosis


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Author Details: Unnati D. Rathod, Ameeta Joshi, Saroj Turbadkar, Nilma Hirani, Abbhay Chawdhary

Volume : 3

Issue : 3

Online ISSN : 2394-5478

Print ISSN : 2394-546X

Article First Page : 322

Article End Page : 328


Abstract

Introduction: Tuberculosis continues to be a major public health problem especially in low income and high incidence countries like India.  Aim of the study was to access and compare sensitivity and specificity of Light emitting Diode Fluorescent Microscopy (LED FM) over Light microscopy (LM) for diagnosis of pulmonary (PTB) and extra pulmonary tuberculosis (EPTB).
Methods: 1446 pulmonary and 328 extra pulmonary cases suspected of tuberculosis were included in the study. Sputum samples were collected on 2 successive days while only one EPTB specimen was received in the laboratory.
Results: Out of 2767 sputum specimen and 328 EPTB specimen evaluated, 603 (21.79%) sputum and 16 (4.84%) EPTB respectively were grown on culture and considered positive for Mycobacterium Tuberculosis. The sensitivity for sputum samples from ZN stain direct smear and concentration sputum smear by LM was 57.88% and 67% respectively, while the specificity of both direct and concentration smears by LM ZN staining was 100%. In case of sputum samples sensitivity of LED FM has drastically increased to 82.09% and the specificity is only slightly lower than LM that is 99.88%. For EPTB sensitivity for direct smear by LM was found to be 12.50% and concentration smear was 18.75% with 100% specificity. With LED FM sensitivity was enhanced by 43.75% with only marginally less specificity as 99.67%. All differences between culture and smear positive were highly statistically significant. (P value <0.0001).
Conclusion: LED FM has higher sensitivity and almost similar specificity (p value <0.0001).  Since it has many beneficial attributes it can be a certain substitute to light microscopy and can improve and decentralize diagnostic services, especially in low and middle income countries (LMIC). Smear microscopy services should be optimized and can be used along with the add on test, to many new diagnostic approaches like cartridge based nucleic acid amplification test (CBNAAT) MTB/RIF GeneXpert.

Keywords
: Extra pulmonary tuberculosis (EPTB), LED Fluorescence microscopy, light microscopy (LM), pulmonary Tuberculosis (PTB), Sensitivity, Specificity