Analysis by PCR and direct DNA sequencing of gyrA mutations associated with fluoroquinolone resistance in Enterococcus faecalis.
A region of gyrA, the gene encoding subunit A of DNA gyrase, that is known to be associated with resistance was amplified and sequenced from 16 Enterococcus faecalis and Enterococcus faecium isolates. Six ciprofloxacin-resistant clinical isolates (MICs of ciprofloxacin, 32 to 64 micrograms/ml) and one multistep resistant laboratory mutant of E. faecalis (MIC of ciprofloxacin, 128 micrograms/ml) contained a change from serine to arginine or to isoleucine at codon 83 or a change from glutamic acid to lysine or to glycine at codon 87 (Escherichia coli GyrA coordinates); these changes have been associated with fluoroquinolone resistance in other species. No difference in the region studied was found in two ciprofloxacin-resistant E. faecium isolates (MICs, 32 micrograms/ml) or in four laboratory derived, spontaneous ciprofloxacin-resistant mutants of E. faecalis (MICs, 8 to 16 micrograms/ml), suggesting that other mechanisms may be responsible for fluoroquinolone resistance in some enterococci.
Korten
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V
Center for Infectious Diseases, University of Texas Medical School, Houston 77030.
Huang
W M
WM
Murray
B E
BE
D000595:Amino Acid Sequence; 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*; D004352:Drug Resistance, Microbial / Q000235:genetics; D013293:Enterococcus faecalis / Q000187:drug effects* / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009154:Mutation; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA / Q000379:methods; D012689:Sequence Homology, Nucleic Acid
D000890:Anti-Infective Agents; D004269:DNA, Bacterial; D002939:Ciprofloxacin; D027081:DNA Gyrase; D004250:DNA Topoisomerases, Type II