Implementation of the INNO-LiPA Rif. TB® line-probe assay in rapid detection of multidrug-resistant tuberculosis in Latvia

Abstract

In Latvia, 11% of tuberculosis (TB) patients have multidrug-resistant TB (MDR-TB). The INNO-LiPA Rif.TB ® line-probe assay (LPA) detects rifampin (RMP) resistance and may accelerate the time to effective MDRTB treatment. To determine the impact of LPA on time to diagnosis, initiation of treatment, sputum culture conversion and treatment outcome. From October 2004 to September 2006, we performed LPA and drug susceptibility testing (DST) using BACTEC and Löwenstein-Jensen (LJ) media among all individuals at risk for MDR-TB compared to a 2003 cohort of 48 MDR-TB patients detected by BACTEC. In a total of 107 sputum smear-positive individuals at risk for MDR-TB, Mycobacterium tuberculosis was isolated from 85; 23 were RMP-resistant on LJ compared to 22 on LPA (96% sensitivity). There was a significant difference in the mean time between specimen collection and LPA result (10.0 days) and BACTEC DST result (17.0 days, P = 0.0005) in the LPA cohort. The LPA cohort achieved culture conversion a median of 105 days after treatment initiation vs. a median of 88.5 days (P = 0.54) in the BACTEC cohort. There was no difference in the proportion achieving culture conversion (P = 0.54) or in treatment outcome ( P = 0.65). LPA accelerated empiric treatment, but did not reduce the time to culture conversion or improve the rate of culture conversion or treatment outcome.