title: Comparison of TaqMan(®) Array Card and MYCOTB(TM) with conventional phenotypic susceptibility testing in MDR-TB.
abstract: Although phenotypic drug susceptibility testing (DST) is endorsed as the standard for second-line drug testing of Mycobacterium tuberculosis, it is slow and laborious.
  
  
  
  We evaluated the accuracy of two faster, easier methodologies that provide results for multiple drugs: a genotypic TaqMan(®) Array Card (TAC) and the Sensititre(®) MYCOTB(TM) plate. Both methods were tested at three central laboratories in Bangladesh, Tanzania, and Thailand with 212 multidrug-resistant tuberculosis (MDR-TB) isolates and compared with the laboratories' phenotypic method in use.
  
  
  
  The overall accuracy for ethambutol, streptomycin, amikacin, kanamycin, ofloxacin, and moxifloxacin vs. the phenotypic standard was 87% for TAC (range 70-99) and 88% for the MYCOTB plate (range 76-98). To adjudicate discordances, we re-defined the standard as the consensus of the three methods, against which the TAC and MYCOTB plate yielded 94-95% accuracy, while the phenotypic result yielded 93%. Some isolates with genotypic mutations and high minimum inhibitory concentration (MIC) were phenotypically susceptible, and some isolates without mutations and low MIC were phenotypically resistant, questioning the phenotypic standard.
  
  
  
  In our view, the TAC, the MYCOTB plate, and the conventional phenotypic method have similar performance for second-line drugs; however, the former methods offer speed, throughput, and quantitative DST information.
authors.affiliation: Department of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: S
authors.initials: S
authors.lastname: Foongladda
authors.affiliation: International Center for Diarrheal Diseases and Research, Dhaka, Bangladesh.
authors.forename: S
authors.initials: S
authors.lastname: Banu
authors.affiliation: Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, Virginia, USA.
authors.forename: S
authors.initials: S
authors.lastname: Pholwat
authors.affiliation: Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, Virginia, USA.
authors.forename: J
authors.initials: J
authors.lastname: Gratz
authors.affiliation: Department of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: S
authors.initials: S
authors.lastname: O-Thong
authors.affiliation: Department of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: N
authors.initials: N
authors.lastname: Nakkerd
authors.affiliation: Department of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: R
authors.initials: R
authors.lastname: Chinli
authors.affiliation: International Center for Diarrheal Diseases and Research, Dhaka, Bangladesh.
authors.forename: S S
authors.initials: SS
authors.lastname: Ferdous
authors.affiliation: International Center for Diarrheal Diseases and Research, Dhaka, Bangladesh.
authors.forename: S M M
authors.initials: SM
authors.lastname: Rahman
authors.affiliation: International Center for Diarrheal Diseases and Research, Dhaka, Bangladesh.
authors.forename: A
authors.initials: A
authors.lastname: Rahman
authors.affiliation: International Center for Diarrheal Diseases and Research, Dhaka, Bangladesh.
authors.forename: S
authors.initials: S
authors.lastname: Ahmed
authors.affiliation: Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, Virginia, USA.
authors.forename: S
authors.initials: S
authors.lastname: Heysell
authors.affiliation: Kilimanjaro Clinical Research Institute, Moshi, Tanzania.
authors.forename: M
authors.initials: M
authors.lastname: Sariko
authors.affiliation: Kilimanjaro Clinical Research Institute, Moshi, Tanzania.
authors.forename: G
authors.initials: G
authors.lastname: Kibiki
authors.affiliation: Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, Virginia, USA.
authors.forename: E
authors.initials: E
authors.lastname: Houpt
mesh_terms: D001459:Bangladesh; D004252:DNA Mutational Analysis / Q000379:methods*; D005838:Genotype; D057166:High-Throughput Screening Assays; D006801:Humans; D008826:Microbial Sensitivity Tests; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D011237:Predictive Value of Tests; D060888:Real-Time Polymerase Chain Reaction; D015203:Reproducibility of Results; D013636:Tanzania; D013785:Thailand; D013997:Time Factors; D018088:Tuberculosis, Multidrug-Resistant / Q000175:diagnosis* / Q000188:drug therapy / Q000382:microbiology; D057188:Workflow