Sheetal Bankar1, Reena Set1, Disha Sharma1, Daksha Shah2, Jayanthi Shastri1. 1. Department of Microbiology, T.N. Medical College and B Y L Nair Ch. Hospital, Mumbai, Maharashtra, India. 2. City TB Officer, Mumbai District Tuberculosis Control Society, Mumbai, Maharashtra, India.
Abstract
INTRODUCTION: The WHO endorsed Xpert Mycobacterium tuberculosis/rifampicin (MTB/RIF) assay, has been evaluated for pulmonary TB in a number of studies but very few have investigated it for extrapulmonary specimens. The present study evaluates the performance of Xpert MTB/RIF assay in the diagnosis of extrapulmonary TB (EPTB). AIM AND OBJECTIVES: The aim of the study is to determine sensitivity and specificity of Xpert MTB/RIF assay for diagnosis of EPTB and RIF resistance in comparison to culture on Lowenstein-Jensen (LJ) medium and proportion method (PM), respectively. MATERIALS AND METHODS: A total of 738 specimens from clinically suspected cases of EPTB were subjected to Ziehl-Neelsen staining, Xpert MTB/RIF assay and culture on LJ medium. PM was done on MTB isolates. RESULTS: The sensitivity, specificity of Xpert MTB/RIF assay for diagnosis of EPTB were 84.91% (95% confidence interval [CI] 72.41%-93.25%) and 86.72% (95% CI 83.94%-89.17%) and for RIF resistance detection were 60.00% (95% CI 32.29%-83.66%) and 94.74% (95% CI 73.97%-99.87%), respectively. Among culture-positive cases, the sensitivity of Xpert MTB/RIF assay was 94.12% in smear positive and 80.56% in smear-negative cases. Xpert MTB/RIF showed maximum sensitivity of MTB detection from lymph node specimens (100% [95% CI 54.07%-100.00%]) and other body fluids (100% [95% CI 15.81%-100.00%]). CONCLUSION: The present study establishes Xpert MTB/RIF assay as a promising tool in the rapid diagnosis of EPTB and detection of RIF resistance.
INTRODUCTION: The WHO endorsed Xpert Mycobacterium tuberculosis/rifampicin (MTB/RIF) assay, has been evaluated for pulmonary TB in a number of studies but very few have investigated it for extrapulmonary specimens. The present study evaluates the performance of Xpert MTB/RIF assay in the diagnosis of extrapulmonary TB (EPTB). AIM AND OBJECTIVES: The aim of the study is to determine sensitivity and specificity of Xpert MTB/RIF assay for diagnosis of EPTB and RIF resistance in comparison to culture on Lowenstein-Jensen (LJ) medium and proportion method (PM), respectively. MATERIALS AND METHODS: A total of 738 specimens from clinically suspected cases of EPTB were subjected to Ziehl-Neelsen staining, Xpert MTB/RIF assay and culture on LJ medium. PM was done on MTB isolates. RESULTS: The sensitivity, specificity of Xpert MTB/RIF assay for diagnosis of EPTB were 84.91% (95% confidence interval [CI] 72.41%-93.25%) and 86.72% (95% CI 83.94%-89.17%) and for RIF resistance detection were 60.00% (95% CI 32.29%-83.66%) and 94.74% (95% CI 73.97%-99.87%), respectively. Among culture-positive cases, the sensitivity of Xpert MTB/RIF assay was 94.12% in smear positive and 80.56% in smear-negative cases. Xpert MTB/RIF showed maximum sensitivity of MTB detection from lymph node specimens (100% [95% CI 54.07%-100.00%]) and other body fluids (100% [95% CI 15.81%-100.00%]). CONCLUSION: The present study establishes Xpert MTB/RIF assay as a promising tool in the rapid diagnosis of EPTB and detection of RIF resistance.