title: Phenotypic changes in ciprofloxacin-resistant Staphylococcus aureus.
abstract: The work described here continues our studies of the effects of subinhibitory concentrations of antibiotics on SOS and DNA repair gene expression in Staphylococcus aureus. Mitomycin C and the new-generation fluoroquinolone moxifloxacin induced expression of SOS response genes (lexA, recA, sosA, and umuC) in a ciprofloxacin-resistant Cip(r)I strain of S. aureus. To examine phenotypic changes in Cip(r) strains mutated in CIP targets (GrlA and/or GyrA), we used Biolog Phenotype MicroArrays. Two other Cip(r) strains mutated in the norA promoter region were used to study the effects of subinhibitory concentrations of DNA-damaging antibiotics on norA expression. We show that mitomycin C and moxifloxacin induced overexpression of the norA gene in Cip(r) strains. Finally, we confirm that subinhibitory concentrations of CIP increase mutation rates in S. aureus.
authors.affiliation: Department of Microbiology and Immunology, University of British Columbia, Life Sciences Institute, 2350 Health Science Mall, Vancouver, BC V6T1Z3, Canada.
authors.forename: Lili R
authors.initials: LR
authors.lastname: Mesak
authors.forename: Julian
authors.initials: J
authors.lastname: Davies
mesh_terms: D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D001372:Aza Compounds / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D002939:Ciprofloxacin / Q000494:pharmacology*; D053843:DNA Mismatch Repair / Q000187:drug effects; D024881:Drug Resistance, Bacterial / Q000235:genetics; D024841:Fluoroquinolones; D015870:Gene Expression / Q000187:drug effects; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D016685:Mitomycin / Q000494:pharmacology; D000077266:Moxifloxacin; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D011804:Quinolines / Q000494:pharmacology; D013014:SOS Response, Genetics / Q000187:drug effects; D013211:Staphylococcus aureus / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism
chemical_list: D000903:Antibiotics, Antineoplastic; D001372:Aza Compounds; D001426:Bacterial Proteins; D002939:Ciprofloxacin; D024841:Fluoroquinolones; D016685:Mitomycin; D000077266:Moxifloxacin; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D011804:Quinolines; C075040:NorA protein, Staphylococcus