title: Discrepancies in Drug Susceptibility Test for Tuberculosis Patients Resulted from the Mixed Infection and the Testing System.
abstract: To find the potential reasons for the discrepancies in the drug susceptibility test (DST) of M. tuberculosis isolates, twenty paired isolates with disputed drug susceptibilities to isoniazid (INH) were selected according to the MGIT960 testing and Löwenstein-Jensen (L-J) proportion methods. Their MICs were confirmed again by broth microdilution method and by L-J proportion method. The spoligotyping results showed that, of all the 20 paired strains, 11 paired isolates belonged to the Beijing genotype and 6 paired isolates belonged to SIT1634, and that each of the remaining 3 paired isolates had two genotypes, namely, SIT1 and SIT1634. Those 3 paired isolates with different intrapair spoligotypes were further confirmed as mixed infection by the results that those three pairs of isolates with different 12 locus MIRU intrapair types and one pair carried different base pair at codon 315 (AGC versus AAC). Totally mutations in the katG gene were identified in 13 paired isolates. No mutations were found in the regulatory sequences and open reading frames (ORF) of the inhA and ahpC genes in any of the tested isolates. Those results showed that the different test systems and the mixed infection with particular genotypes of M. tuberculosis strains contributed to the drug susceptibility discrepancies.
authors.affiliation: Department of Tuberculosis, Tianjin Haihe Hospital, Tianjin 300350, China ; Tianjin Respiratory Disease Research Institute, Tianjin 300350, China.
authors.forename: Zaoxian
authors.initials: Z
authors.lastname: Mei
authors.affiliation: National Tuberculosis Clinical Laboratory, Beijing Chest Hospital, Capital Medical University, Beijing 101149, China ; Beijing Key Laboratory in Drug Resistant Tuberculosis Research, Beijing Tuberculosis & Thoratic Tumor Research Institute, Beijing 101149, China.
authors.forename: Zhaogang
authors.initials: Z
authors.lastname: Sun
authors.affiliation: Department of Tuberculosis, Tianjin Haihe Hospital, Tianjin 300350, China ; Tianjin Respiratory Disease Research Institute, Tianjin 300350, China.
authors.forename: Dapeng
authors.initials: D
authors.lastname: Bai
authors.affiliation: National Tuberculosis Clinical Laboratory, Beijing Chest Hospital, Capital Medical University, Beijing 101149, China ; Beijing Key Laboratory in Drug Resistant Tuberculosis Research, Beijing Tuberculosis & Thoratic Tumor Research Institute, Beijing 101149, China.
authors.forename: Yuhui
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Department of Tuberculosis, Tianjin Haihe Hospital, Tianjin 300350, China ; Tianjin Respiratory Disease Research Institute, Tianjin 300350, China.
authors.forename: Zhiling
authors.initials: Z
authors.lastname: Li
authors.affiliation: National Tuberculosis Clinical Laboratory, Beijing Chest Hospital, Capital Medical University, Beijing 101149, China ; Beijing Key Laboratory in Drug Resistant Tuberculosis Research, Beijing Tuberculosis & Thoratic Tumor Research Institute, Beijing 101149, China.
authors.forename: Hairong
authors.initials: H
authors.lastname: Huang
authors.affiliation: National Tuberculosis Clinical Laboratory, Beijing Chest Hospital, Capital Medical University, Beijing 101149, China ; Beijing Key Laboratory in Drug Resistant Tuberculosis Research, Beijing Tuberculosis & Thoratic Tumor Research Institute, Beijing 101149, China.
authors.forename: Chuanyou
authors.initials: C
authors.lastname: Li
authors.affiliation: National Tuberculosis Clinical Laboratory, Beijing Chest Hospital, Capital Medical University, Beijing 101149, China ; Beijing Key Laboratory in Drug Resistant Tuberculosis Research, Beijing Tuberculosis & Thoratic Tumor Research Institute, Beijing 101149, China.
authors.forename: Shaofa
authors.initials: S
authors.lastname: Xu
authors.affiliation: Department of Tuberculosis, Tianjin Haihe Hospital, Tianjin 300350, China ; Tianjin Respiratory Disease Research Institute, Tianjin 300350, China.
authors.forename: Li
authors.initials: L
authors.lastname: Li
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D002374:Catalase / Q000235:genetics*; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D006801:Humans; D007538:Isoniazid / Q000008:administration & dosage; D008826:Microbial Sensitivity Tests; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000235:genetics* / Q000472:pathogenicity; D014376:Tuberculosis / Q000188:drug therapy / Q000235:genetics* / Q000382:microbiology / Q000473:pathology
chemical_list: D001426:Bacterial Proteins; D002374:Catalase; C480353:katG protein, Mycobacterium tuberculosis; D007538:Isoniazid