Accuracy of Xpert(®) MTB/RIF assay compared with AdvanSure™ TB/NTM real-time PCR using bronchoscopy specimens

The performance of Xpert(®) MTB/RIF assay, an automated nucleic acid amplification test (NAAT) that was developed for the detection of tuberculosis (TB), has been evaluated in various clinical settings. However, few studies have compared Xpert with other NAATs, especially its performance using lower respiratory tract specimens (LRTS).

To compare the practical diagnostic performance of the Xpert assay with that of the AdvanSure™ TB/NTM RT-PCR kit in the detection of pulmonary TB (PTB), using LRTS obtained through bronchoscopy.

Of 249 patients included, 105 had culture-confirmed PTB. Using culture as reference, the overall sensitivity of Xpert and AdvanSure was respectively 92.4% and 83.8%. When acid-fast bacilli smear results were taken into consideration, the sensitivity of Xpert for smear-positive and smear-negative LRTS was respectively 100% and 88.9%, while that of the AdvanSure was 100% and 76.4%. Xpert showed better results than AdvanSure in terms of sensitivity in smear-negative LRTS (P = 0.012), but no difference in smear-positive LRTS.

Xpert may be advantageous in the detection of PTB using LRTS, particularly in low microbiological burden settings.