Validation of the GenoType<sup>® </sup>MTBDR<it>plus </it>assay for detection of MDR-TB in a public health laboratory in Thailand

<p>Abstract</p> <p>Background</p> <p>Over the past several years, new diagnostic techniques have been developed to allow for the rapid detection of multidrug resistant tuberculosis. The GenoType<sup>® </sup>MTBDR<it>plus </it>test is a deoxyribon...

Full description

Bibliographic Details
Main Authors: Podewils Laura, Sinthuwattanawibool Chalinthorn, Anek-vorapong Rapeepun, McCarthy Kimberly, Ngamlert Keerataya, Promsarin Busakorn, Varma Jay K
Format: Article
Language:English
Published: BMC 2010-05-01
Series:BMC Infectious Diseases
Online Access:http://www.biomedcentral.com/1471-2334/10/123
Description
Summary:<p>Abstract</p> <p>Background</p> <p>Over the past several years, new diagnostic techniques have been developed to allow for the rapid detection of multidrug resistant tuberculosis. The GenoType<sup>® </sup>MTBDR<it>plus </it>test is a deoxyribonucleic acid (DNA) strip assay which uses polymerase chain reaction (PCR) and hybridization to detect genetic mutations in the genes that confer isoniazid (INH) and rifampn (RIF) resistance. This assay has demonstrated good performance and a rapid time to results, making this a promising tool to accelerate MDR-TB diagnosis and improve MDR-TB control. Validation of rapid tests for MDR-TB detection in different settings is needed to ensure acceptable performance, particularly in Asia, which has the largest number of MDR-TB cases in the world but only one previous report, in Vietnam, about the performance of the GenoType<sup>® </sup>MDR<it>plus </it>assay. Thailand is ranked 18<sup>th </sup>of 22 "high-burden" TB countries in the world, and there is evidence to suggest that rates of MDR-TB are increasing in Thailand. We compared the performance of the GenoType<sup>® </sup>MTBDR<it>plus </it>assay to Mycobacterial Growth Indicator Tube for Antimycobacterial Susceptibility Testing (MGIT AST) for detection INH resistance, RIF resistance, and MDR-TB in stored acid-fast bacilli (AFB)-positive sputum specimens and isolates at a Public TB laboratory in Bangkok, Thailand.</p> <p>Methods</p> <p>50 stored isolates and 164 stored AFB-positive sputum specimens were tested using both the MGIT AST and the GenoType<sup>® </sup>MTBDR<it>plus </it>assay.</p> <p>Results</p> <p>The GenoType<sup>® </sup>MTBDR<it>plus </it>assay had a sensitivity of 95.3%, 100%, and 94.4% for INH resistance, RIF resistance, and MDR-TB, respectively. The difference in sensitivity between sputum specimens (93%) and isolates (100%) for INH resistance was not statistically significant (p = 0.08). Specificity was 100% for all resistance patterns and for both specimens and isolates. The laboratory processing time was a median of 25 days for MGIT AST and 5 days for the GenoType<sup>® </sup>MTBDR<it>plus </it>(p < 0.01).</p> <p>Conclusion</p> <p>The GenoType<sup>® </sup>MTBDR<it>plus </it>assay has been validated as a rapid and reliable first-line diagnostic test on AFB-positive sputum or MTB isolates for INH resistance, RIF resistance, and MDR-TB in Bangkok, Thailand. Further studies are needed to evaluate its impact on treatment outcome and the feasibility and cost associated with widespread implementation.</p>
ISSN:1471-2334