Journal article
Mechanisms and Frequency of Resistance to Premafloxacin in Staphylococcus aureus: Novel Mutations Suggest Novel Drug-Target Interactions
Antimicrobial agents and chemotherapy, Vol.44(12), pp.3344-3350
12/2000
DOI: 10.1128/AAC.44.12.3344-3350.2000
PMCID: PMC90203
PMID: 11083638
Abstract
Premafloxacin is a novel 8-methoxy fluoroquinolone with enhanced activity against
Staphylococcus aureus
. We found premafloxacin to be 32-fold more active than ciprofloxacin against wild-type
S. aureus
. Single mutations in either subunit of topoisomerase IV caused a four- to eightfold increase in the MICs of both quinolones. A double mutation (
gyrA
and either
grlA
or
grlB
) caused a 32-fold increase in the MIC of premafloxacin, while the MIC of ciprofloxacin increased 128-fold. Premafloxacin appeared to be a poor substrate for NorA, with NorA overexpression causing an increase of twofold or less in the MIC of premafloxacin in comparison to a fourfold increase in the MIC of ciprofloxacin. The frequency of selection of resistant mutants was 6.4 × 10
−10
to 4.0 × 10
−7
at twofold the MIC of premafloxacin, 2 to 4 log
10
less than that with ciprofloxacin. Single-step mutants could not be selected at higher concentrations of premafloxacin. In five single-step mutants, only one previously described uncommon mutation (Ala116Glu), and four novel mutations (Arg43Cys, Asp69Tyr, Ala176Thr, and Pro157Leu), three of which were outside the quinolone resistance-determining region (QRDR) were found. Genetic linkage studies, in which incross of
grlA
+
and outcross of mutations were performed, showed a high correlation between the mutations and the resistance phenotypes, and allelic exchange experiments confirmed the role of the novel mutations in
grlA
in resistance. Our results suggest that although topoisomerase IV is the primary target of premafloxacin, premafloxacin appears to interact with topoisomerase IV in a manner different from that of other quinolones and that the range of the QRDR of
grlA
should be expanded.
Details
- Title: Subtitle
- Mechanisms and Frequency of Resistance to Premafloxacin in Staphylococcus aureus: Novel Mutations Suggest Novel Drug-Target Interactions
- Creators
- Dilek Ince - Infectious Disease Division and Medical Services, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114-2696David C Hooper - Infectious Disease Division and Medical Services, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114-2696
- Resource Type
- Journal article
- Publication Details
- Antimicrobial agents and chemotherapy, Vol.44(12), pp.3344-3350
- DOI
- 10.1128/AAC.44.12.3344-3350.2000
- PMID
- 11083638
- PMCID
- PMC90203
- NLM abbreviation
- Antimicrob Agents Chemother
- ISSN
- 0066-4804
- eISSN
- 1098-6596
- Publisher
- American Society for Microbiology
- Language
- English
- Date published
- 12/2000
- Academic Unit
- Infectious Diseases; Internal Medicine
- Record Identifier
- 9984094479802771
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