title: Molecular epidemiology of fluoroquinolone resistance in invasive clinical isolates of Streptococcus pneumoniae in Seville.
abstract: BACKGROUND
  Due to the emergence of drug-resistant pneumococcal isolates, new fluoroquinolones have been recommended for the treatment of pneumococcal infections. The purpose of this study was to establish surveillance, and to conduct molecular characterization, of fluoroquinolone-resistant Streptococcus pneumoniae in Seville.
  
  
  METHODS
  Norfloxacin-resistant S. pneumoniae isolates were characterized by quinolone resistance-determining region (QRDR) substitutions, reserpine-sensitive efflux, serotype and by pulsed-field gel electrophoresis (PFGE) patterns.
  
  
  RESULTS
  Fourteen isolates (5.1%) showed an MIC>16 μg/ml to norfloxacin. Eight of 10 adult isolates were susceptible to levofloxacin. The 4 infant isolates with norfloxacin MIC>16 μg/ml were susceptible to levofloxacin. Seven of these 12 low-level-resistant isolates had mutations in ParC, while mutations both in ParC and GyrA genes were only detected in one of the two high-level-resistant isolates. All the isolates without QRDR substitutions that remained norfloxacin-resistant were positive for reserpine-inhibited efflux. The serotyping and PFGE revealed significant heterogeneity. We obtained 9 different profiles, 3 of which had two isolates each. Two of the isolates with the same pulsotype were from the same patient. The first isolate showed a mutation in the QRDR of ParC, and the second one had an additional GyrA mutation.
  
  
  CONCLUSIONS
  In our study a levofloxacin resistance rate of 0.7% was found among invasive isolates. Although resistance level is low, surveillance is necessary, especially to prevent cases of in vivo resistance development as reported.
authors.affiliation: Microbiology Department, University of Seville, Spain. pat_ira@hotmail.com
authors.forename: Patricia
authors.initials: P
authors.lastname: Iraurgui
authors.forename: María José
authors.initials: MJ
authors.lastname: Torres
authors.forename: Javier
authors.initials: J
authors.lastname: Aznar
mesh_terms: D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D001692:Biological Transport / Q000187:drug effects; D027081:DNA Gyrase / Q000235:genetics; D004252:DNA Mutational Analysis; D027101:DNA Topoisomerase IV / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D024841:Fluoroquinolones / Q000494:pharmacology*; D006801:Humans; D007223:Infant; D007589:Job Syndrome / Q000382:microbiology; D064704:Levofloxacin; D008297:Male; D008826:Microbial Sensitivity Tests; D009643:Norfloxacin / Q000494:pharmacology; D015242:Ofloxacin / Q000494:pharmacology; D011008:Pneumococcal Infections / Q000453:epidemiology / Q000382:microbiology*; D012110:Reserpine / Q000494:pharmacology; D012703:Serotyping; D013030:Spain / Q000453:epidemiology; D013296:Streptococcus pneumoniae / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D024841:Fluoroquinolones; D064704:Levofloxacin; D012110:Reserpine; D015242:Ofloxacin; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase; D009643:Norfloxacin