Abstract:

Objective To investigate Xpert MTB/RIF assay for the rapid determination of Mycobacterium tuberculosis （MTB） and rifampin resistance. Methods A total of 616 sputum or bronchoalveolar lavage fluid （BALF） samples from patients with pulmonary tuberculosis and suspected with pulmonary tuberculosis in Anhui Provincial Chest Hospital were collected from April 2015 to December 2015．Diagnostic performance of Xpert MTB/RIF assay,liquid culturing and acid-fast staining smear microscopy was evaluated,according to gold standard for statistical analysis. Results The sensitivities for MTB determination were 39.61%（225/568）,36.44%（207/568）and 17.78%（101/568）for Xpert MTB/RIF assay,liquid culturing and acid-fast staining smear microscopy. There was a consistency for sensitivities between Xpert MTB/RIF assay and liquid culturing（χ²=1.21,P>0.05）,and the sensitivity of Xpert MTB/RIF assay was higher than that of acid-fast staining smear microscopy（χ²=66.15,P<0.05）. For rifampin resistance determinatin,the rifampin resistance rate by Xpert MTB/RIF assay was 19.40%（39/201）,the sensitivity and specificity were 94.59% （35/37） and 97.56% （160/164） , and there was no statistical significance compared with liquid culturing（χ²= 0.167,P>0.05）. All cultures being positive for rifampin resistance gene were performed for sequencing as the gold standard of rpoB resistance gene determination. For Xpert MTB / RIF assay,the main rifampin resistance locus was Probe E（58.98%,23/39）. S531L and L533P were main in sequencing（62.16%,23/37）. The 2 methods had the same mutation locus （χ²=0.081,P>0.05）. Conclusions Xpert MTB/RIF assay can be used for the rapid determination of MTB and rifampin resistance.

Key words: Mycobacterium tuberculosis, Rifampin, Drug resistance, Xpert MTB / RIF assay