title: 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 9 months. 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 24 months, 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.
authors.affiliation: Department of Orthopaedics, Spinal Disorders Surgery, Christian Medical College, Ida Scudder Road, Vellore, Tamil Nadu, 632004, India. svjustin.arockiaraj@gmail.com.
authors.forename: Justin
authors.initials: J
authors.lastname: Arockiaraj
authors.affiliation: Department of Microbiology, Christian Medical College, Ida Scudder Road, Vellore, 632004, India.
authors.forename: Joy S
authors.initials: JS
authors.lastname: Michael
authors.affiliation: Department of Orthopaedics, Spinal Disorders Surgery, Christian Medical College, Ida Scudder Road, Vellore, Tamil Nadu, 632004, India.
authors.forename: Rohit
authors.initials: R
authors.lastname: Amritanand
authors.affiliation: Department of Orthopaedics, Spinal Disorders Surgery, Christian Medical College, Ida Scudder Road, Vellore, Tamil Nadu, 632004, India.
authors.forename: Kenny Samuel
authors.initials: KS
authors.lastname: David
authors.affiliation: Department of Orthopaedics, Spinal Disorders Surgery, Christian Medical College, Ida Scudder Road, Vellore, Tamil Nadu, 632004, India.
authors.forename: Venkatesh
authors.initials: V
authors.lastname: Krishnan
mesh_terms: D015299:Discitis / Q000175:diagnosis* / Q000382:microbiology; D024881:Drug Resistance, Bacterial; D006801:Humans; D058889:Molecular Typing / Q000379:methods*; D009169:Mycobacterium tuberculosis / Q000235:genetics*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014399:Tuberculosis, Spinal / Q000175:diagnosis* / Q000382:microbiology
keywords: Diagnosis; Rifampicin; Treatment; Tuberculosis; Xpert MTB/RIF assay