Rapid Detection of Rifampicin and Isoniazid Resistant Mycobacterium tuberculosis Using Genotype MTBDRplus Assay in Nepal

Abstract

Rapid line probe assay (LPA) can be a practical and rapid alternative to the slow conventional phenotypic drug susceptibility testing (DST) for detection of drug resistant tuberculosis (TB). The purpose of this study is to determine the diagnostic accuracy of Genotype MTBDRplus, LPA for TB, and compare its performance with conventional DST. A total of 54 culture samples were analyzed for DST using both conventional proportion method and MTBDRplus, where conventional DST identified 43 isolates (79.6%) as drug resistant. Among these 43 drug resistant isolates, 30 isolates (69.7%) were found to be multidrug resistant (MDR). Of all observed mutations using MTBDRplus, codon 531 of rpoB gene and codon 315 of katG gene were found to have highest mutational frequency for RIF resistance (64.7%) and INH resistance (96.8%), respectively. In the present study, MTBDRplus assay was shown to have excellent specificity (100%) for both RIF and INH resistance while sensitivity of the assay was little lower with value of 89.4% for RIF resistance and 91.4% for INH resistance. Therefore, the assay can be a rapid, reliable, and promising molecular test for early detection of MDR-TB in Nepal.

Evaluation of FluoroType MTB for direct detection of Mycobacterium tuberculosis complex and GenoType MTBDRplus for determining rifampicin and isoniazid resistance

“…For the GenoType MTBDRplus assay, previous studies have reported the sensitivity, specificity, PPV and NPV values in detecting INH resistance as ranging between 60%-100%, 95.1%-100%, 97.4%-100% and 90.7%-100%, respectively. In addition, this assay's sensitivity, specificity, PPV and NPV values in detecting RIF resistance are in the range of 82.3%-100%, 73.2%-100%, 81%-100% and 98.9%-100%, respectively [16][17][18][19][20][21][22][23][24][25]. When the results were evaluated, this assay seemed to be more sensitive for detecting RIF resistance than INH resistance.…”

Use of Genotype MTBDRplus Assay for Diagnosis of Multidrug-Resistant Tuberculosis in Nepal

“…Genomic DNA of Mycobacterial culture was extracted by incubating the colonies dissolved in 300 μ L of molecular biology grade water for 20 minutes at 95°C in water bath followed by 15 minutes in ultrasonic bath and centrifugation for 5 minutes at 12000 rpm [ 2 ]. Polymerase chain reaction (PCR) and hybridization were performed following manufacturer's recommendations (Hain Lifescience, Nehren, Germany) [ 6 ].…”

“…Tuberculosis is a serious public health problem mainly in developing countries [ 1 ]. More than 95% of the tuberculosis cases and deaths related to tuberculosis occur in poorer countries [ 2 ]. Further, the multidrug-resistant tuberculosis is emerging as a serious threat to tuberculosis control programs in developing countries [ 2 ].…”

“…More than 95% of the tuberculosis cases and deaths related to tuberculosis occur in poorer countries [ 2 ]. Further, the multidrug-resistant tuberculosis is emerging as a serious threat to tuberculosis control programs in developing countries [ 2 ]. According to World Health Organization (WHO) report, in 2012 around 450,000 people developed MDR-TB, among which 170,000 people died [ 3 ].…”

“…According to World Health Organization (WHO) report, in 2012 around 450,000 people developed MDR-TB, among which 170,000 people died [ 3 ]. Nepal is situated between two countries (China and India) with high MDR-TB prevalence [ 2 ]. According to recent drug resistance surveillance in Nepal, 2.6% of new cases and 17.6% of previously treated cases were MDR-TB positive [ 4 ].…”