The role of Xpert MTB/RIF assay in the diagnosis of tubercular spondylodiscitis.

Abstract

This study aims to assess the accuracy of the Xpert MTB/RIF assay in the diagnosis of tubercular spondylodiscitis and to identify its role in detecting Rifampicin resistance in patients with infective spondylodiscitis. A retrospective study including 348 patients suspected to have infective spondylodiscitis was done. Tissue/pus samples obtained were sent for culture, histopathology and Xpert MTB/RIF assay. All patients who were confirmed to have tubercular spondylodiscitis and those patients who were suspected on clinico-radiological basis were also treated with anti-tuberculous chemotherapy for a period of 9months. The efficacy of the Xpert MTB/RIF assay was assessed in terms of sensitivity and specificity when compared to culture, histopathology, and Composite reference standard (CRS). During this study period of 24months, a total of 348 patients were treated for infective spondylodiscitis. 254 patients were treated for tuberculosis following a smear positivity, culture positivity, and histopathology report or empirically based on clinico-radiological findings. The sensitivity and specificity of the Xpert MTB/RIF assay when compared to culture were 88.4 and 63.7%, respectively. When compared to both culture and histopathology reports it was 80.9 and 80.6%. The sensitivity and specificity of the Xpert MTB/RIF assay when compared to composite reference standard were 71.2 and 100%, respectively. The sensitivity of the assay to detect Rifampicin resistance was 100%. The prevalence of Rifampicin resistance was 5.1%. This study recommends Xpert MTB/RIF assay for early detection of Mycobacterium tubercular spondylodiscitis and Rifampicin resistance.