title: Extensively and pre-extensively drug resistant tuberculosis in clinical isolates of multi-drug resistant tuberculosis using classical second line drugs (levofloxacin and amikacin).
abstract: OBJECTIVE
  To find out the frequency of Extensively Drug Resistant (XDR) and pre-XDR tuberculosis in clinical isolates of Multi-Drug Resistant (MDR) Tuberculosis (TB) by determining the susceptibilities against Levofloxacin and Amikacin (classical second line antituberculosis drugs).
  
  
  METHODS
  Adescriptive cross-sectional study.
  
  
  METHODS
  Microbiology Department, Armed Forces Institute of Pathology (AFIP), Rawalpindi, from September 2011 to August 2013.
  
  
  METHODS
  Amikacin (AK) and Levofloxacin (LEVO) were obtained in chemically pure form from Sigma (Taufkirchen, Germany). The breakpoint concentration used for AK was 1.0 µg/ml and for LEVO 2.0 µg/ml. Mycobacterial Growth Indicator Tube (MGIT) 960 system was used to carry out drug susceptibility testing as per recommended protocol.
  
  
  RESULTS
  A total of 3 MDR-TB isolates (3%) turned out to be XDR-TB based upon simultaneous resistance to injectable second line antituberculosis drug AK and one of the fluoro-quinolones (LEVO). A total of 24 MDR-TB isolates (24%) were found to be pre-XDR based upon resistance to LEVO alone. Treatment status record of patients with XDR and pre-XDRTB isolates revealed that majority of patients had received fluoroquinolones (FQs) during the course of treatment.
  
  
  CONCLUSIONS
  XDR-TB has started to emerge in MDR-TB isolates in our set up. The worrying sign is the high frequency of pre-XDR tuberculosis. Urgent steps need to be taken to stem the tide of pre-XDR-TB in our population. It is thus recommended to develop facilities to carry out drug susceptibility testing to monitor the status of pre-XDR and XDR-TB in our population.
authors.affiliation: Department of Microbiology, PNS Shifa, Karachi.
authors.forename: Irfan Ali
authors.initials: IA
authors.lastname: Mirza
authors.affiliation: Department of Microbiology, Rai Medical College, Sargodha.
authors.forename: Farooq Ahmad
authors.initials: FA
authors.lastname: Khan
authors.affiliation: Department of Microbiology, Baqai Medical University, Karachi.
authors.forename: Khursheed Ali
authors.initials: KA
authors.lastname: Khan
authors.affiliation: Department of Microbiology, Combined Military Hospital, Quetta.
authors.forename: Luqman
authors.initials: L
authors.lastname: Satti
authors.affiliation: Department of Microbiology, Armed Forces Institute of Pathology (AFIP), Rawalpindi.
authors.forename: Tahir
authors.initials: T
authors.lastname: Ghafoor
authors.affiliation: Department of Microbiology, Armed Forces Institute of Pathology (AFIP), Rawalpindi.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Fayyaz
mesh_terms: D000583:Amikacin / Q000627:therapeutic use*; D000995:Antitubercular Agents / Q000627:therapeutic use*; D003430:Cross-Sectional Studies; D054908:Extensively Drug-Resistant Tuberculosis / Q000175:diagnosis / Q000188:drug therapy*; D005260:Female; D006801:Humans; D064704:Levofloxacin / Q000627:therapeutic use*; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000302:isolation & purification; D055815:Young Adult
chemical_list: D000995:Antitubercular Agents; D064704:Levofloxacin; D000583:Amikacin