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Genotype MTBDRplus for detection of rifampin and isoniacid resistance in clinical specimens of M. tuberculosis

Abstract number: R2497

Causse M., Ruiz P., Gutierrez J., Casal M.

Objective: The present study sought to evaluate the use of the new Genotype MTBDRplus assay (Hain Lifescience GmbH, Nehren, Germany) directly from positive clinical specimens, comparing the results with those obtained by conventional phenotypic resistance studies.

Methods: 59 bacilloscopy-positive sputum samples from patients with suspected tuberculosis were subjected to the new Genotype MTBDRplus assay. This technique is based on DNA-strip technology, consisting of a multiplex PCR in combination with reverse hybridisation using nitrocellulose strips for detecting mutations related with Rifampin (RIF) and Isoniacid (INH) resistance comparing the result with those obtained phenotypically in Bactec MGIT 960.

Result: Of the 59 M. tuberculosis strains tested, 9 were phenotypically sensitive to INH and RMP, and displayed no resistance-linked mutations. Among the 50 sputum specimens showing some form of phenotypic resistance, 13 displayed RMP resistance, 14 INH resistance and 23 Multi-drug resistance (MDR). All of the phenotypically RIF resistances were detected by the test and only two of the INH resistant strains could not be detected. Sensitivity for RIF resistance is 100% in our study and 94.5% for INH.

Conclusions: The new Genotype MTBDRplus assay is a valid technique for detecting resistance to RMP and INH, providing within 6–8 hours a result that enables a more effective orientation of patient treatment.

Since the detection of resistance-related mutations did not cover 100% of possible cases of resistance, use of this new assay does not obviate the need for conventional phenotypic resistance testing.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Barcelona, Spain
Presentation type:
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