title: Performance of Cepheid ® Xpert MTB/RIF ® and TB-Biochip ® MDR in two regions of Russia with a high prevalence of drug-resistant tuberculosis.
abstract: The purpose of this study was to assess the performance of Cepheid® Xpert MTB/RIF® ("Xpert") and TB-Biochip® MDR ("TB-Biochip"). Sputum specimens from adults with presumptive tuberculosis (TB) were homogenized and split for: (1) direct Xpert and microscopy, and (2) concentration for Xpert, microscopy, culture [Lowenstein-Jensen (LJ) solid media and Mycobacteria Growth Indicator Tube® (MGIT)], indirect drug susceptibility testing (DST) using the absolute concentration method and MGIT, and TB-Biochip. In total, 109 of 238 (45.8 %) specimens were culture-positive for Mycobacterium tuberculosis complex (MTBC), and, of these, 67 isolates were rifampicin resistant (RIF-R) by phenotypic DST and 64/67 (95.5 %) were isoniazid resistant (INH-R). Compared to culture of the same specimen, a single direct Xpert was more sensitive for detecting MTBC [95.3 %, 95 % confidence interval (CI), 90.0-98.3 %] than direct (59.6 %, 95 % CI, 50.2-68.5 %) or concentrated smear (85.3 %, 95 % CI, 77.7-91.1 %) or LJ culture (80.8 %, 95 % CI, 72.4-87.5 %); the specificity was 86.0 % (95 % CI, 78.9-91.3 %). Compared with MGIT DST, Xpert correctly identified 98.2 % (95 % CI, 91.5-99.9 %) of RIF-R and 95.5 % (95 % CI, 85.8-99.2 %) of RIF-susceptible (RIF-S) specimens. In a subset of 104 specimens, the sensitivity of TB-Biochip for MTBC detection compared to culture was 97.3 % (95 % CI, 91.0-99.5 %); the specificity was 78.1 % (95 % CI, 61.5-89.9 %). TB-Biochip correctly identified 100 % (95 % CI, 94.2-100 %) of RIF-R, 94.7 % (95 % CI, 76.7-99.7 %) of RIF-S, 98.2 % (95 % CI, 91.4-99.9 %) of INH-R, and 78.6 % (95 % CI, 52.1-94.2 %) of INH-S specimens compared to MGIT DST. Xpert and Biochip were similar in accuracy for detecting MTBC and RIF resistance compared to conventional culture methods.
authors.affiliation: The U.S. Centers for Disease Control and Prevention, CDC, Atlanta, GA 30333, USA.
authors.forename: E V
authors.initials: EV
authors.lastname: Kurbatova
authors.forename: D A
authors.initials: DA
authors.lastname: Kaminski
authors.forename: V V
authors.initials: VV
authors.lastname: Erokhin
authors.forename: G V
authors.initials: GV
authors.lastname: Volchenkov
authors.forename: S N
authors.initials: SN
authors.lastname: Andreevskaya
authors.forename: L N
authors.initials: LN
authors.lastname: Chernousova
authors.forename: O V
authors.initials: OV
authors.lastname: Demikhova
authors.forename: J V
authors.initials: JV
authors.lastname: Ershova
authors.forename: N V
authors.initials: NV
authors.lastname: Kaunetis
authors.forename: T A
authors.initials: TA
authors.lastname: Kuznetsova
authors.forename: E E
authors.initials: EE
authors.lastname: Larionova
authors.forename: T G
authors.initials: TG
authors.lastname: Smirnova
authors.forename: T R
authors.initials: TR
authors.lastname: Somova
authors.forename: I A
authors.initials: IA
authors.lastname: Vasilieva
authors.forename: A V
authors.initials: AV
authors.lastname: Vorobieva
authors.forename: S S
authors.initials: SS
authors.lastname: Zolkina
authors.forename: J P
authors.initials: JP
authors.lastname: Cegielski
mesh_terms: D000328:Adult; D001431:Bacteriological Techniques / Q000379:methods; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D015995:Prevalence; D015203:Reproducibility of Results; D012426:Russia / Q000453:epidemiology; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology; D018088:Tuberculosis, Multidrug-Resistant / Q000175:diagnosis* / Q000453:epidemiology