title: Outcomes of pulmonary MDR-TB: impacts of fluoroquinolone resistance and linezolid treatment.
abstract: OBJECTIVE
  Fluoroquinolones (FQs) are the most important second-line drugs for MDR-TB treatment. Therapeutic options for FQ-resistant (FQ-R) MDR/XDR-TB are very limited. The purpose of the present study was to determine treatment outcomes and risk factors associated with unfavourable outcomes of MDR/XDR-TB, focusing on the impacts of FQ-R status and linezolid treatment.
  
  
  METHODS
  This was a retrospective cohort study of 337 MDR-TB patients, including 144 (42.7%) FQ-R MDR/XDR-TB cases. Treatment outcomes were evaluated according to WHO 2013 recommendations.
  
  
  RESULTS
  Later-generation FQs such as levofloxacin or moxifloxacin were given to 331 (98.2%) patients. Overall, favourable outcomes were achieved in 272 (80.7%) patients. FQ-R second-line injectable drug-susceptible MDR [adjusted OR (aOR) 4.299, 95% CI 1.239-14.916, P = 0.015] and XDR status (aOR 6.294, 95% CI 1.204-32.909, P = 0.024) were independently associated with unfavourable outcomes. However, FQ-susceptible (FQ-S) second-line injectable drug-resistant MDR status was not associated with unfavourable outcomes (aOR 1.814, 95% CI 0.314-10.485, P = 0.999). Favourable treatment outcomes were more frequent in FQ-R MDR/XDR-TB patients who received linezolid (82.8%) compared with those who did not receive linezolid (58.1%, P = 0.002). When FQ-R MDR/XDR-TB treatment without linezolid was used as a reference, the addition of linezolid was associated with favourable outcomes (aOR 4.081, 95% CI 1.237-13.460, P = 0.017), comparable to those for FQ-S MDR-TB (aOR 4.341, 95% CI 1.470-12.822, P = 0.005).
  
  
  CONCLUSIONS
  Later-generation FQs could improve treatment outcomes of patients with MDR-TB. Linezolid should be considered for inclusion in FQ-R MDR/XDR-TB treatment regimens.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Byeong-Ho
authors.initials: BH
authors.lastname: Jeong
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Kyeongman
authors.initials: K
authors.lastname: Jeon
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Hye Yun
authors.initials: HY
authors.lastname: Park
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: O Jung
authors.initials: OJ
authors.lastname: Kwon
authors.affiliation: Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Kyung Soo
authors.initials: KS
authors.lastname: Lee
authors.affiliation: Department of Thoracic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Hong Kwan
authors.initials: HK
authors.lastname: Kim
authors.affiliation: Department of Thoracic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Yong Soo
authors.initials: YS
authors.lastname: Choi
authors.affiliation: Department of Thoracic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Jhingook
authors.initials: J
authors.lastname: Kim
authors.affiliation: Department of Laboratory Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Hee Jae
authors.initials: HJ
authors.lastname: Huh
authors.affiliation: Department of Laboratory Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Nam Yong
authors.initials: NY
authors.lastname: Lee
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea wjkoh@skku.edu.
authors.forename: Won-Jung
authors.initials: WJ
authors.lastname: Koh
mesh_terms: D000328:Adult; D000995:Antitubercular Agents / Q000494:pharmacology* / Q000627:therapeutic use*; D015331:Cohort Studies; D024901:Drug Resistance, Multiple, Bacterial; D005260:Female; D024841:Fluoroquinolones / Q000494:pharmacology*; D006801:Humans; D000069349:Linezolid / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D016896:Treatment Outcome; D018088:Tuberculosis, Multidrug-Resistant / Q000188:drug therapy*
chemical_list: D000995:Antitubercular Agents; D024841:Fluoroquinolones; D000069349:Linezolid