Effect of Xpert MTB/RIF on the treatment of multi-drug-resistant or rifampicin-resistant tuberculosis screened out from re-treatment pulmonary tuberculosis patients, a prospective cohort study.

Background: Re-treatment pulmonary tuberculosis (PTB) has a high risk of being multi-drug-or rifampicin-resistant tuberculosis (MDR/RR-TB). The Xpert MTB/RIF assay possesses high efficacy for the evaluation of rifampicin resistance. The aim of the present study was to assess the benefit of the Xpert MTB/ RIF assay in the screening and treatment of MDR/RR-TB in re-treatment PTB patients. Methods: Patients with suspected re-treatment PTB were prospectively enrolled and divided into Xpert MTB/RIF and mycobacterial tuberculosis (MTB) culture groups. No Xpert MTB/RIF assay was carried out in the MTB culture group. The diagnostic performance and turn-around time (TAT) of MDR/RRTB detection and the culture results of MDR/RR-TB patients following two-month chemotherapy in two groups were calculated and compared. Results: Using phenotypic DST as a reference standard, the positive predictive value of Xpert MTB/RIF for the detection of RR-TB and MDR-TB among re-treatment PTB patients was 90.72% and 77.32%, respectively. The Xpert MTB/RIF group had a significantly shorter interval for the initiation of anti-MDR/RR-TB treatment {1 [1-1] vs. 52 [47-57] days, P<0.0001}; and following two-month chemotherapy, the percentage of positive culture MDR/RR-TB patients in the Xpert MTB/RIF group was significantly reduced (24.18% vs. 50%, P=0.0003). Conclusions: Xpert MTB/RIF can accurately screen MDR/RR-TB among re-treatment PTB patients, reducing both the turn-around time for therapy initiation and the percentage of positive culture MDR/RR-TB patients following two-month chemotherapy. This is not only beneficial for treatment but also for reducing MDR-TB transmission. We recommend that re-treatment PTB patients receive anti-RR/TB chemotherapy following a positive RFP resistance result in the Xpert MTB/RIF assay.