Characterization of sparfloxacin-resistant mutants of Staphylococcus aureus obtained in vitro.
A sparfloxacin-susceptible clinical isolate of Staphylococcus aureus was grown in increased concentrations of sparfoxacin. The presence of mutations in gyrA, gyrB, grlA and grlB genes was analyzed. The primary point mutation was located in the gyrA gene (Glu-88 to Lys). Two further mutation steps appeared in the amino acid change Ser-80 to Tyr in GrlA. No mutations occurred in the gyrB or grlB genes. Efflux pumps involved in the increase of resistance were also found to affect norfloxacin and ciprofloxacin. This effect may be related to NorA. An overexpression of NorA, may be associated with the increase of the MIC of norfloxacin from 32 mg/l to >200 mg/l in the final mutant. The MICs levels of sparfloxacin were affected by unknown mechanism.
Ruiz
J
J
Laboratori de Microbiologia, Instituto de Infecciones e Inmunologia, IDIBAPS, Hospital Clinic, School of Medicine, University of Barcelona, Villarroel 170, 08036, Barcelona, Spain.
Sierra
J M
JM
De Anta
M T
MT
Vila
J
J
D000890:Anti-Infective Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D027081:DNA Gyrase / Q000235:genetics*; D027101:DNA Topoisomerase IV / Q000235:genetics*; D024881:Drug Resistance, Bacterial / Q000235:genetics; D024841:Fluoroquinolones; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D017354:Point Mutation; D017422:Sequence Analysis, DNA; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics / Q000254:growth & development
D000890:Anti-Infective Agents; D001426:Bacterial Proteins; D027081:DNA Gyrase; D027101:DNA Topoisomerase IV; D024841:Fluoroquinolones; D027425:ATP-Binding Cassette, Sub-Family C Proteins; C075040:NorA protein, Staphylococcus; C061363:sparfloxacin