Evaluation of the Genotype(R) MTBDRplus assay as a tool for drug resistance surveys

L Rigouts, AS Hoza, P De Rijk, G Torrea, TM Chonde, D Basra, M Zignol, F van Leth, SM Egwaga, A Van Deun

    Research output: Contribution to journalA1: Web of Science-article

    Abstract

    SETTING: A national tuberculosis (TB) drug resistance survey in Tanzania. OBJECTIVE: To compare the performance of the Genotype(R) MTBDRplus line-probe assay (LPA) on smear-positive sputum specimens with conventional culture and isoniazid (INH) plus rifampicin (RMP) drug susceptibility testing (DST). DESIGN: Mycobacterium tuberculosis isolates tested at the Tanzanian Central TB Reference Laboratory (CTRL) were submitted for quality assurance of phenotypic DST to its supranational reference laboratory (SRL), together with ethanol-preserved sputum specimens for LPA DST. RESULTS: Only 321 samples could be tested using LPA; of these, three were identified as being non-tuberculous mycobacteria using CTRL DST. Both tests had 269 sets with interpretable results. CTRL DST yielded almost the same number of interpretable results as LPA, with 90% concordance (kappa = 0.612, P < 0.001). Five (1.9%) multidrug-resistant (MDR) strains, 46 (17.1%) resistant to INH only and 0 RMP only, were found by CTRL DST. For the LPA, these results were respectively 5 (1.9%), 26 (9.7%) and 2 (0.7%). With SRL DST as the gold standard, LPA was more accurate than CTRL DST for RMP, but missed almost half the INH-resistant samples. CONCLUSION: LPA applied directly on ethanol-preserved sputum specimens was similar to phenotypic DST in terms of yield of interpretable results. Although probably more accurate for RMP and MDR-TB, it appears to seriously underestimate INH resistance. Considering speed, easy and safe specimen transportation and low infrastructure requirements, LPA DST from sputum can be recommended for surveys in resource-poor settings.
    Original languageEnglish
    JournalInternational Journal of Tuberculosis and Lung Disease
    Volume15
    Issue number7
    Pages (from-to)959-965
    ISSN1027-3719
    DOIs
    Publication statusPublished - 2011

    Keywords

    • B780-tropical-medicine
    • Bacterial diseases
    • Tuberculosis
    • Mycobacterium tuberculosis
    • Drug susceptibility
    • Drug resistance
    • Isoniazid
    • Rifampicin
    • Testing
    • Multidrug resistance
    • Comparison
    • Performance
    • Rapid diagnostic tests
    • Assays
    • Smear-positive
    • Sputum
    • Line probe assay
    • Laboratory techniques and procedures

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