Evaluation of the CombiChip Mycobacteria Drug-Resistance detection DNA chip for identifying mutations associated with resistance to isoniazid and rifampin in Mycobacterium tuberculosis.
ABSTRACT The CombiChip Mycobacteriatrade mark Drug-Resistance Detection DNA chip, recently developed by GeneIn (Pusan, South Korea), is an oligonucleotide microchip coupled with polymerase chain reaction for the detection of mutations associated with resistance to isoniazid (INH) and rifampin (RIF). This oligonucleotide chip was compared with DNA sequencing and phenotypic drug susceptibility testing with 69 INH- and/or RIF-resistant and 27 all tested drug-susceptible Mycobacterium tuberculosis isolates. Two selected codons (the katG codon 315 and inhA15) allowed identification of 84.1% of INH-resistant isolates and 100% of RIF resistance were detected by screening for 7 codons: rpoB511, rpoB513, rpoB516, rpoB522, rpoB526, rpoB531, and rpoB533. The overall specificity of this oligonucleotide chip for detecting INH and RIF resistance were 100 and 95.3%, respectively. This level of sensitivity and specificity is concordant with that from the determination of M. tuberculosis drug resistance by DNA sequencing. This oligonucleotide chip is a rapid and reliable genotypic method capable of detecting multiple mutations associated with INH and RIF resistance simultaneously in a single microchip slide.
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ABSTRACT: To rapidly detect rifampicin (RIF), isoniazid (INH) and multidrug resistance (MDR) in Mycobacterium tuberculosis isolates, a new system (BluePoint MtbDR, Bio Concept Inc., Taichung, Taiwan) including an oligonucleotide array and an automatic reader was evaluated. The array simultaneously identifies M. tuberculosis and predominant mutations in the rpoB, katG and inhA upstream regulatory region (inhA-r) genes. The system was assessed with 324 clinical M. tuberculosis isolates, including 210 MDR, 41 RIF mono-resistant, 34 INH mono-resistant and 39 fully susceptible isolates. The results were compared with those obtained using the GenoType MTBDRplus test, drug-resistant gene sequencing and conventional drug susceptibility testing. The detection limit of the array was 25 pg DNA. The array and the GenoType MTBDRplus test detected 179 (85.2%) and 182 (86.7%) MDR M. tuberculosis strains, respectively. The sensitivities of the array for detecting RIF and INH resistance were 98.4% and 87.7%, respectively, whereas the sensitivities of the GenoType MTBDRplus test for detecting RIF and INH resistance were 98.8% and 88.9%, respectively. No significant difference was found between the tests with respect to their sensitivities to detect MDR (p=0.66), RIF resistance (p=0.69) or INH resistance (p=0.68). The discrepancies were mainly attributed to rare mutations in inhA-r, which were not included in the array. The array can directly reveal transmission-associated mutations, which are useful for epidemiological investigations. The turnaround time of the array test was 6-7 h. This study confirms the feasibility of this system for rapid and accurate diagnosis of INH and RIF resistance in M. tuberculosis. This article is protected by copyright. All rights reserved.Clinical Microbiology and Infection 12/2013; · 4.58 Impact Factor
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ABSTRACT: RK. Tuberculosis and Molecular Diagnosis. WebmedCentral BIOTECHNOLOGY 2013;4(2):WMC003992 Copyright: This is an open-access article distributed under the terms of the Creative Commons Attribution License(CC-BY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.04/2013;
Article: Tuberculosis and Molecular Diagnosis[Show abstract] [Hide abstract]
ABSTRACT: The incidence of Tuberculosis varies considerably around the world and most Mycobacterial infections in developing nations are still being caused by Mycobacterium tuberculosis members. A quick and correct diagnosis is of great importance because of the high morbidity. Unfortunately, conventional bacteriological methods are time consuming, their sensitivity is low, and so treatment occasionally becomes empirical. PCR method has high specificity in identifying M. tuberculosis in various specimens. Molecular diagnostic tools for Tuberculosis (TB) have evolved quickly with new innovations which can provide unprecedented opportunities for the rapid, sensitive and specific diagnosis of M. tuberculosis in clinical specimens and the status of its drug sensitivity. Microscopy and culture methods can not be replaced but the molecular assays can be applied in parallel with any new molecular tests for the diagnosis of TB. For extra pulmonary specimens, the use of the amplification methods is advocated, since rapid and accurate laboratory diagnosis is critical. Customization of the diagnostic usefulness of a molecular assay, according to the ease, reliability and need for health care sector is of immense value in a modern clinical Mycobacteriology laboratory.Biotechnology (Reading, Mass.) 02/2013; 2013;4(2).