Utility Of Auramine-Rhodamine Stain And Gene Xpert Pcr In Diagnosis Of Tuberculosis During Fnac Procedure

Abstract

Background: Tuberculosis (TB) is a major public health problem in India. The most common presentation of extrapulmonary TB is lymphadenopathy. The clinical parameters for the diagnosis of EPTB are neither specific nor does their absence exclude tuberculosis involvement. Recently WHO recommended Gene Xpert to be used as one of the initial diagnostic test in patients suspected to have extrapulmonary TB. The Gene Xpert test is a cartridge-based nucleic acid amplification assay which diagnoses TB by detecting the presence of causative bacteria, as well as Rifampicin resistant strains of TB. Objective: Statistical evaluation of Auramine-Rhodamine (AR) stain and Gene Xpert (Nucleic acid amplification test) utility in the detection of Mycobacterial tuberculosis (including Rifampicin resistance), in FNAC procedure for clinically suspected EPTB. Methods: All clinically suspected cases of extrapulmonary TB, referred for FNAC procedure at Department of Pathology, Shri B.M.Patil Medical College, Hospital and Research Center, BLDE (Deemed to be University), Vijayapura was included in the present study. Routinely stained FNAC smears with Giemsa, PAP and H&E stain were examined. Special methods like Ziehl-Neelsen (ZN) stained and Auramine Rhodamine (AR) stained smears were examined for acid-fast bacilli(AFB). Aspirated material remaining in the needle hub/syringe was rinsed with phosphate buffer and subjected for Gene Xpert test. Procedure for sampling for AR stain and Gene Xpert test have been elaborated. Results: In the present study of 108 cases, the mean age was 30.6years. Overall ZN stain positivity was in 18.5%, AR stain showed 31.4% positivity and Gene Xpert test showed positivity of 56.4%. On combining AR stain and Gene Xpert assay, additional 31.4% cases of TB were picked up. 25% of additional cases which were AR stain negative, were found positive on Gene Xpert. 9.2% of cases did not show correlation between cytomorphological features and ZN stain, AR stain and Gene Xpert test.Conclusion: From the present study, we conclude that by using the AR stain and Gene Xpert test, we can confirm more cases of TB along with Multi-Drug Resistant cases on FNAC procedure and help in early initiation of treatment