TITLE:
Evaluation of Xpert MTB/RIF Ultra for Diagnosis of Extrapulmonary Tuberculosis: A Retrospective Analysis in a Low-Tuberculosis Prevalence Setting
AUTHORS:
Annalisa Del Giudice, Rossella Perna, Teresa Baldoni, Francesco Scarano, Annunziata De Rosa, Agostina Pontarelli, Mario De Marco, Martha Alicia Falca, Clelia Di Tella, Luigi Atripaldi, Sergio Alfonso Harari, Andrea Bianco, Roberto Parrella
KEYWORDS:
Extrapulmonary Tuberculosis, Molecular Diagnosis, Mycobacterium tuberculosis, Xpert® MTB/RIF Ultra
JOURNAL NAME:
Journal of Tuberculosis Research,
Vol.9 No.3,
September
27,
2021
ABSTRACT: Background: Extrapulmonary tuberculosis (EPTB) remains difficult to diagnose because the
clinical specimens to be examined are often paucibacillary and obtained with difficulty from inaccessible sites. An updated Xpert® MTB/RIF Ultra (Ultra) test
has been designed and licensed to improve sensitivity in the detection of
Mycobacterium tuberculosis complex. The aim of the present study is to evaluate the
performance of Ultra assay for the clinical diagnosis of EPTB in a low tuberculosis prevalence country. Methods: A retrospective analysis was
performed at “A. O dei Colli” of Naples on consecutive extrapulmonary
specimens for EPTB across a three-year period. All different types of
extrapulmonary specimens were tested for EPTB by smear microscopy, culture and
Ultra assay in accordance with relevant guidelines. Results: A total of 606 EPTB samples, 561 culture negative EPTB and 45 culture
positive EPTB were included. Using culture as reference standard, the overall
sensitivities and specificities of Ultra assay were 95.6% (95% CI 84.8 - 99.5) and 97.5% (95% CI 95.8 - 98.6) respectively. Sensitivity and specificity of
Ultra for individual category of specimens were also performed. Conclusion: In a low-tuberculosis
prevalence setting, Ultra assay confirms to have a good performance in the
diagnosis of EPTB for all different extrapulmonary samples.