Comparison of Real-time PCR Fluorescence Melting Curve Analysis and Xpert MTB/RIF for Detection of Rifampicin Resistant Mycobacterium Tuberculosis from Patients with Extra-Pulmonary Tuberculosis

Abstract

Objective: Compare the real-time fluorescent Polymerase Chain Reaction (PCR) melting curve analysis (MCA) with Xpert MTB/RIF for detection of rifampicin resistant Mycobacterium tuberculosis (RRTB) from extra-pulmonary tuberculosis (EPTB). Methods: The medical records of patients with EPTB were reviewed and collected from February 2017 to February 2019. The samples were tested by drug susceptibility tests. Taking the rifampicin resistance (RR) result of proportional method as the gold standard, the sensitivity, specificity and coincidence rate of MCA and Xpert method to detect RR was calculated. Results: There were 134 samples enrolled in this study including 75 males and 59 females. The results of RR were consistent with MCA and Xpert methods in 123 cases. 106 cases were consistent with results of the proportional method detection. Taking the proportional method as the standard, the sensitivity, specificity, positive predictive value, negative predictive value and coincidence rate of Xpert method to detect RR were 95.2%, 83.7%, 72.7%, 97.5%, 87.3%; the MCA method were 90.5%, 73.9%, 61.3%, 94.4% and 79.1% respectively. There were significant differences on the detection of RIF sensitivity in the different types of patients detected by two methods (P<0.01). Conclusion: Xpert and MCA had high sensitivity and specificity in detecting surgical specimens of patients with EPTB and were suitable for early and rapid detection of RRTB from EPTB.