Multiplex polymerase chain reaction using insertion sequence 6110 (IS6110) and mycobacterial protein fraction from BCG of Rm 0.64 in electrophoresis target genes for diagnosis of tuberculous lymphadenitis.

PURPOSE

Tubercular lymphadenitis (TBLA) is a common manifestations of extrapulmonary tuberculosis (EPTB) accounting for 30-40% of cases. Prompt diagnosis and timely initiation of anti-tubercular therapy (ATT) is the key for successful clinical outcome. This study was carried out to evaluate multiplex polymerase chain reaction (MPCR) using MPB64 and IS6110, and compare with the conventional methods for rapid diagnosis of TBLA.

MATERIALS AND METHODS

In our study, lymph node fine-needle aspirates of patients were evaluated for TBLA. They were classified as Group I: TBLA group, divided into (a) Confirmed TBLA cases (n0 = 80): Culture/smear-positive or cytological examination showing presence of epithelioid cell granuloma with or without multinucleate giant cell and caseation necrosis with presence of AFB, and (b) suspected TBLA cases ( n = 30): Culture/smear-negative and cytological examination showing presence of epithelioid cell granuloma and response to ATT and Group II (Control) (n = 25): Patients of lymphadenopathy confirmed to be caused by other diseases such as sarcoidosis, lymphoma, etc., All samples were subjected to conventional tests and MPCR. For MPCR we used Mycobacterium tuberculosis-specific deoxyribonucleic acid sequences specific for the MPB64 and IS6110 region.

RESULTS

In the confirmed TBLA group, Ziehl-Neelsen (ZN) smear, cytology, culture, and MPCR positivity was 30%, 70%, 26.3%, and 91.3% respectively. In the suspected TBLA group, smear and culture were negative, and sensitivity of cytology and MPCR was 73.3% and 86.6%, respectively. In the control group all tests were found to be negative, thus giving a specificity of 100% to all the tests in the study.

CONCLUSION

In conclusion, techniques like MPCR with high sensitivity and specificity can play an important role in rapid diagnosis of TBLA.