title: Occurrence of single-point gyrA mutations among ciprofloxacin-susceptible Escherichia coli isolates causing urinary tract infections in Latin America.
abstract: To detect if isolates susceptible to quinolones already carry mutations in the gyrA and parC genes, we selected 12 ciprofloxacin-susceptible Escherichia coli strains collected from patients with urinary tract infections in Latin America in 1998, as part of ongoing SENTRY Antimicrobial Surveillance Program. The isolates studied exhibited minimal inhibitory concentrations (MICs) for ciprofloxacin between < or = 0.015 microg/mL and 0.5 microg/mL. The molecular characterization of quinolone resistance was determinated by amplification of the gyrA and parC by PCR followed by sequencing of the respective amplicons. We observed that E. coli isolates exhibiting MIC, < or = 0.06 microg/mL for ciprofloxacin did not show mutations in either topoisomerase. On the other hand, all isolates with MIC between 0.12 microg/mL and 0.5 microg/mL demonstrated single mutation in the gyrA gene. The most frequent mutation occurred at position 83, where the amino acid serine was replaced by leucine. No mutations in the parC gene were observed. To preserve the potency and prevent the development of resistance, we suggest that quinolone usage should be rational, especially in the treatment of urinary tract infections, and in the prophylaxis of immunosupressed patient populations.
authors.affiliation: Department of Pathology, University of Iowa College of Medicine, Iowa City 52242, USA. galesa@mail.medadmin.uiowa.edu
authors.forename: A C
authors.initials: AC
authors.lastname: Gales
authors.forename: K A
authors.initials: KA
authors.lastname: Gordon
authors.forename: W W
authors.initials: WW
authors.lastname: Wilke
authors.forename: M A
authors.initials: MA
authors.lastname: Pfaller
authors.forename: R N
authors.initials: RN
authors.lastname: Jones
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology*; D001483:Base Sequence; D002939:Ciprofloxacin / Q000494:pharmacology*; D027081:DNA Gyrase; D004250:DNA Topoisomerases, Type II / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics*; D004305:Dose-Response Relationship, Drug; D004352:Drug Resistance, Microbial / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics*; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D006801:Humans; D015994:Incidence; D007843:Latin America / Q000453:epidemiology; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D011159:Population Surveillance; D014552:Urinary Tract Infections / Q000453:epidemiology / Q000382:microbiology*
chemical_list: D000890:Anti-Infective Agents; D004269:DNA, Bacterial; D002939:Ciprofloxacin; D027081:DNA Gyrase; D004250:DNA Topoisomerases, Type II