Premium
Diagnostic performance of fluorescent light‐emitting diode microscopy for tuberculous lymphadenitis in a high‐burden setting
Author(s) -
Abdissa Ketema,
Tadesse Mulualem,
Abdella Kedir,
Bekele Alemayehu,
Bezabih Mesele,
Abebe Gemeda
Publication year - 2015
Publication title -
tropical medicine and international health
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.056
H-Index - 114
eISSN - 1365-3156
pISSN - 1360-2276
DOI - 10.1111/tmi.12585
Subject(s) - ziehl–neelsen stain , medicine , tuberculous lymphadenitis , tuberculosis , microscopy , pathology , fluorescence microscope , mycobacterium tuberculosis , cytology , fluorescence , sputum , acid fast , physics , quantum mechanics
Objective Diagnosis of tuberculous lymphadenitis using fine‐needle aspiration cytology is a simple and safe but low‐specificity method, whereas conventional smear microscopy has variable sensitivity due to low bacterial load. We evaluated the diagnostic performance of fluorescent light‐emitting diode ( LED ) microscopy on routinely collected fine‐needle aspirates from tuberculous lymphadenitis presumptive cases. Methods Fine‐needle aspirates were collected from patients clinically suspected of having tuberculous lymphadenitis as part of routine diagnosis. Smear preparation was performed from the aspirate and processed for cytology, conventional Ziehl–Neelsen and LED microscopy. The remaining aspirate was processed for culture on Lowenstein–Jensen media. Capilia TB ‐Neo test was used to differentiate M. tuberculosis complex from non‐tuberculous mycobacteria. Result A total of 144 tuberculous lymphadenitis presumptive cases were included. 66.7% (96/144) were positive for M. tuberculosis complex on culture. Only one isolate was identified as non‐tuberculous mycobacteria. The detection rates of Ziehl–Neelsen and LED microscopy were 18.8% (27/144) and 34% (49/144), respectively. As compared to culture, sensitivity was 25.0% [95% CI : 16.3–33.7] for Ziehl–Neelsen microscopy and 45.8% [95% CI : 35.9–55.8] for LED microscopy. The specificity was 93.8% [95% CI : 86.9–100] for Ziehl–Neelsen microscopy and 89.6% [95% CI : 80.9–98.2] for LED microscopy. LED microscopy showed a statistically significant increase in sensitivity and similar specificity compared to Ziehl–Neelsen microscopy. Mean reading time of positive slides was 2.62 min/slide for Ziehl–Neelsen and 1.60 min/slide for LED microscopy. Cytology showed sensitivity of 82.3% and specificity of 54.2%. LED microscopy detected TB bacilli in 33.3% of cases cytologically classified as suppurative abscess. Conclusion The LED microscopy for tuberculous lymphadenitis had significantly higher sensitivity and shorter screening time than Ziehl–Neelsen microscopy. Use of LED microscopy among cases classified as suppurative abscess on fine‐needle aspirate cytology improves evidence‐based diagnosis of presumptive tuberculous lymphadenitis cases. Moreover, LED microscopy could be considered as an alternative approach in settings where fine‐needle aspirate cytology is impractical.