title: Discordance between Xpert MTB/RIF assay and Bactec MGIT 960 Culture System for detection of rifampin-resistant Mycobacterium tuberculosis isolates in a country with a low tuberculosis (TB) incidence.
abstract: Among 452 samples that were positive by the Xpert MTB/RIF (Xpert) assay and MGIT 960 system (MGIT), 440 and 10 Mycobacterium tuberculosis samples were detected as rifampin susceptible and rifampin resistant, respectively. Two isolates that were rifampin susceptible by the MGIT system were rifampin resistant by the Xpert assay. rpoB sequencing identified a silent (CTG521TTG) mutation in one isolate and a missense (GAC516TAC) mutation in another. The detection of rifampin resistance is imperfect with both the Xpert assay and MGIT system. Any discordant rifampin resistance results should be confirmed by sequencing of the rpoB gene.
authors.affiliation: Department of Microbiology, Faculty of Medicine, Kuwait University, Safat, Kuwait Kuwait National TB Reference Laboratory, Shuwaikh, Kuwait.
authors.forename: Eiman
authors.initials: E
authors.lastname: Mokaddas
authors.affiliation: Department of Microbiology, Faculty of Medicine, Kuwait University, Safat, Kuwait suhail_ah@hsc.edu.kw.
authors.forename: Suhail
authors.initials: S
authors.lastname: Ahmad
authors.affiliation: Kuwait National TB Reference Laboratory, Shuwaikh, Kuwait.
authors.forename: Hanaa S
authors.initials: HS
authors.lastname: Eldeen
authors.affiliation: Department of Microbiology, Faculty of Medicine, Kuwait University, Safat, Kuwait.
authors.forename: Noura
authors.initials: N
authors.lastname: Al-Mutairi
mesh_terms: D000995:Antitubercular Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001431:Bacteriological Techniques / Q000379:methods*; D012321:DNA-Directed RNA Polymerases; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D007730:Kuwait / Q000453:epidemiology; D008969:Molecular Sequence Data; D012293:Rifampin / Q000494:pharmacology*; D018088:Tuberculosis, Multidrug-Resistant / Q000453:epidemiology / Q000382:microbiology*
chemical_list: D000995:Antitubercular Agents; D001426:Bacterial Proteins; C505805:rpoB protein, Mycobacterium tuberculosis; D012321:DNA-Directed RNA Polymerases; D012293:Rifampin