Dot-ELISA vs. PCR of fine needle aspirates of tuberculous lymphadenitis: a prospective study in India

OBJECTIVE: To evaluate an in-house dot-enzyme-linked immunosorbent assay (ELISA) for confirmation of clinically suspected cases of tuberculous lymphadenitis (TBLN). STUDY DESIGN: The study was performed at the postgraduate departments of microbiology and pathology of a tertiary-care teaching hospital in India. Suspected cases of TBLN were prospectively enrolled. Fine needle aspiration was done of enlarged lymph nodes in all patients, and 2 smears were prepared, 1 for acid-fast bacillus (AFB) demonstration and the other for cytologic examination. The remaining material was tested with in-house dot-ELISA and by IS6110 amplification with polymerase chain reaction (PCR), for diagnosis of TBLN. RESULTS: ELISA was more sensitive and detected 93.2% of cases. PCR and fine needle aspiration cytology (FNAC) detected 82.5% and 61.0% cases, respectively. AFB positivity was 33.1%. CONCLUSION: Application of dot-ELISA was more sensitive but less specific as compared to PCR. PCR, though expensive, should be used in problem cases because of its high specificity.