title: [Fluoroquinolone resistance determining region mutation in Streptococcus pneumonia isolates].
abstract: OBJECTIVE
  To investigate the relationship between different fluoroquinolone (FQ) resistance of Streptococcus pneumoniae and the mutations of target genes.
  
  
  METHODS
  A total of 232 Streptococcus pneumoniae isolates were collected from 12 teaching hospitals at 9 cities between June and December 2010. The antibacterial activities of 16 antimicrobial agents were determined by agar dilution method. The ciprofloxacin, levofloxacin and moxifloxacin MIC ≥ 1 mg/L isolates were selected to detect the mutations in QRDR (parC, parE, and gyrA genes) through PCR combined sequencing.
  
  
  RESULTS
  The susceptible rates of ciprofloxacin, levofloxacin and moxifloxacin were 53.9% (125/232) , 98.7% (229/232) , 98.7% (229/232) .Forty-three strains were randomly selected to be analyzed, including 19 levofloxacin MIC ≥ 2 mg/L strains and 24 levofloxacin MIC = 1 mg/L strains. The MIC of levofloxacin were 1-2 mg/L, ciprofloxacin were 2 mg/L and moxifloxacin were 0.125-0.250 mg/L when a single mutation in parE occurred. The MIC of levofloxacin were 2 mg/L, ciprofloxacin were 4 mg/L and moxifloxacin were 0.25 mg/L or 0.50 mg/L when mutations in both parE and parC occurred. The MIC of levofloxacin were 16 mg/L, ciprofloxacin were ≥ 16 mg/L and moxifloxacin were 4 mg/L when mutations in both parE and gyrA occurred.
  
  
  CONCLUSIONS
  The single mutation in parE/parC is associated with low level levofloxacin and ciprofloxacin resistance, while double mutations in both parC/parE and gyrA are associated with moxifloxacin resistance.
authors: Department of Clinical Laboratory, Peking University People's Hospital,Beijing 100044, China.
authors: Fei-fei
authors: FF
authors: Zhang
authors: Department of Clinical Laboratory, Peking University People's Hospital,Beijing 100044, China.
authors: Chun-jiang
authors: CJ
authors: Zhao
authors: Department of Clinical Laboratory, Peking University People's Hospital,Beijing 100044, China. Email: whuibj@gmail.com.
authors: Hui
authors: H
authors: Wang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002648:Child; D002675:Child, Preschool; D002939:Ciprofloxacin / Q000494:pharmacology; D027081:DNA Gyrase / Q000235:genetics; D027101:DNA Topoisomerase IV / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D005260:Female; D024841:Fluoroquinolones / Q000494:pharmacology*; D005798:Genes, Bacterial; D006801:Humans; D064704:Levofloxacin / Q000494:pharmacology; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D009154:Mutation; D011008:Pneumococcal Infections / Q000188:drug therapy / Q000382:microbiology; D016133:Polymerase Chain Reaction; D013296:Streptococcus pneumoniae / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones; D002939:Ciprofloxacin; D064704:Levofloxacin; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase