Performance of the GenoType® MTBDRPlus assay in routine settings: a multicenter study

Former Soviet Union countries including the Baltic States (Latvia, Lithuania, and Estonia) are hot spots for an emerging epidemic of drug resistant tuberculosis (TB). As a part of the development of a co-ordinated network of centers for diagnostic trials across Eastern Europe we conducted a retrospective multicenter analysis of the performance of the GenoType® MTBDR Plus assay for TB identification and susceptibility to isoniazid (INH) and rifampicin (RIF) in routine settings. A total of 1,045 primary samples, 1045 TB cultures derived from these specimens and 306 separate M. tuberculosis isolates tested in 2007–2010 at four participating sites (Tartu, Estonia; Riga, Latvia; Vilnius, Lithuania; and Samara, Russian Federation) were included in the analysis. The pooled sensitivity and specificity values for RIF and INH were 95.3% and 95.5%, 89.9 and 87.1%, respectively; there were no statistically significant variations in performance across sites. The proportion of multidrug resistant (MDR) strains in the collections ranged from 21.8% (in Estonia) to 55.9% (in Russia). In a routine non-trial context, the assay reliably detected both rifampicin and isoniazid resistance. The absence of statistically significant differences between sites suggested that the comparable performance obtained using these assays has helped demonstrate the formation of a successful diagnostic trial network.