title: Disputed rpoB mutations can frequently cause important rifampicin resistance among new tuberculosis patients.
abstract: METHODS
  Greater Mymensingh area, Bangladesh.
  
  
  OBJECTIVE
  To document among new tuberculosis (TB) patients the proportions and treatment outcomes of silent, non-disputed and disputed (generally missed by rapid drug susceptibility testing [DST]) rpoB mutations, and their detection by commercial molecular assays.
  
  
  METHODS
  Retrospective analysis of rpoB sequences from randomly selected ethanol-preserved diagnostic sputum samples; comparison of sequencing with conventional DST results and standard first-line treatment outcome; retesting of samples with mutations using the Xpert MTB/RIF and GenoType MTBDRplus assays.
  
  
  RESULTS
  Of 1091 samples, 5.8% failed amplification, and six contained other mycobacteria. In 2005 and 2010, respectively 2/500 (0.4%) and 11/522 (2.1%) amplicons showed non-silent mutations. At least 7/13 of these belonged to the disputed group, with 5/7 patients suffering adverse treatment outcome. One silent mutation went undetected by commercial assays. Following routine DST indications, only three cases with a non-silent mutation were eventually detected.
  
  
  CONCLUSIONS
  Disputed rpoB mutations may be responsible for the majority of rifampicin (RMP) resistance among new cases, and lead to adverse outcomes of first-line treatment. Silent mutations do not necessarily cause Xpert or line-probe assay false RMP-resistant results. Molecular RMP DST could greatly simplify resistance surveillance, in addition to offering the best prospects for early and accurate individual diagnosis.
authors.affiliation: Mycobacteriology Unit, Institute of Tropical Medicine, Antwerp, Belgium; International Union Against Tuberculosis and Lung Disease, Paris, France.
authors.forename: A
authors.initials: A
authors.lastname: Van Deun
authors.affiliation: Damien Foundation, Dhaka, Bangladesh.
authors.forename: K J M
authors.initials: KJ
authors.lastname: Aung
authors.affiliation: Damien Foundation, Dhaka, Bangladesh.
authors.forename: A
authors.initials: A
authors.lastname: Hossain
authors.affiliation: Mycobacteriology Unit, Institute of Tropical Medicine, Antwerp, Belgium.
authors.forename: P
authors.initials: P
authors.lastname: de Rijk
authors.affiliation: Mycobacteriology Unit, Institute of Tropical Medicine, Antwerp, Belgium.
authors.forename: M
authors.initials: M
authors.lastname: Gumusboga
authors.affiliation: Mycobacteriology Unit, Institute of Tropical Medicine, Antwerp, Belgium; Department of Biomedical Sciences, Antwerp, Belgium.
authors.forename: L
authors.initials: L
authors.lastname: Rigouts
authors.affiliation: Mycobacteriology Unit, Institute of Tropical Medicine, Antwerp, Belgium; New York University, New York, New York, USA.
authors.forename: B C
authors.initials: BC
authors.lastname: de Jong
mesh_terms: D000995:Antitubercular Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics*; D001459:Bangladesh; D012321:DNA-Directed RNA Polymerases; D024881:Drug Resistance, Bacterial; D006801:Humans; D008826:Microbial Sensitivity Tests; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000235:genetics; D021141:Nucleic Acid Amplification Techniques; D012189:Retrospective Studies; D012293:Rifampin / Q000494:pharmacology*; D013183:Sputum / Q000382:microbiology; D014376:Tuberculosis / Q000188:drug therapy / Q000382:microbiology
chemical_list: D000995:Antitubercular Agents; D001426:Bacterial Proteins; C505805:rpoB protein, Mycobacterium tuberculosis; D012321:DNA-Directed RNA Polymerases; D012293:Rifampin