Evaluation of the Genotype® MTBDRplus assay as a tool for drug resistance surveys

L. Rigouts, A.S. Hoza, P. De Rijk, G. Torrea, T.M. Chonde, D. Basra, M. Zignol, F. Van Leth, S.M. Egwaga, A. Van Deun

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

SETTING: A national tuberculosis (TB) drug resistance survey in Tanzania. OBJECTIVE: To compare the performance of the Genotype® 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 (κ = 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. © 2011 The Union.
Original languageEnglish
Pages (from-to)959-965
JournalInternational journal of tuberculosis and lung disease
Volume15
Issue number7
DOIs
Publication statusPublished - Jul 2011
Externally publishedYes

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