Evaluation of the GenoType® MTBDRplus assay and identification of a rare mutation for improving MDR-TB detection
DESIGN: Using MTBDRplus, drug susceptibility testing (DST) and DNA sequencing, 237 Mycobacterium tuberculosis strains were tested.
RESULTS: The sensitivity of MTBDRplus was 75.0% (126/168) for isoniazid (INH) resistant strains, and 93.5% (157/168) for rifampicin (RMP) resistant strains. It correlated well with sequencing, with 94.9% and 99.6% agreement for each strain category and 100% specificity for all categories. The two most common rpoB mutations were S531L (53.6%, 90/168) and D516G (17.3%, 29/168) in RMP-resistant strains. INH resistance was dominated by the katG 315 locus (S to T, N, R, I) mutation (73.7%, 124/168), and a rare katG mutation, S315N (6.5%, 11/168), not covered by MTBDRplus was identified. The mutation combination inhA−15/inhA−8 and katG315 (34 strains) was characteristically displayed in MDR-TB strains (23.5%), but not in INH-monoresistant strains.
CONCLUSIONS: Although Genotype MTBDRplus is a rapid and reliable molecular test for detecting MDR-TB, a significant proportion of strains in China contain a rare katG S315N mutation that would be missed by the assay. Further improvements may be achieved by incorporating this mutation into the assay to increase sensitivity in detecting INH resistance in China.
Document Type: Research Article
Affiliations: 1: Department of Infectious Diseases, Huashan Hospital, Fudan University, Shanghai, China 2: Department of Infectious Diseases, Huashan Hospital, Fudan University, Shanghai, China; Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, USA 3: Chongqing Pulmonary Hospital, Chongqing, China 4: Department of Infectious Diseases, Huashan Hospital, Fudan University, Shanghai, China; Institutes of Biomedical Sciences, Fudan University, Shanghai, China
Publication date: 01 April 2012
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