Characterization of Mycoplasma hominis mutations involved in resistance to fluoroquinolones.
Fluoroquinolone-resistant mutants of Mycoplasma hominis were selected in vitro from the PG21 susceptible reference strain either by multistep selection on increasing concentrations of various fluoroquinolones or by one-step selection on agar medium with ofloxacin. The quinolone resistance-determining regions (QRDR) of the structural genes encoding the A and b subunits of DNA gyrase were amplified by PCR, and the nucleotide sequences of eight multistep-selected resistant strains were compared to those of susceptible strain PG21. Four high-level resistant mutants that were selected on norfloxacin or ofloxacin contained a C-to-T transition in the gyrA QRDR, leading to substitution of Ser-83 by Leu in the GyrA protein. Analysis of the sequence of the gyrB QRDR of the eight multistep-selected mutants did not reveal any difference compared to that of the gyrB QRDR of the reference strain M. hominis PG21. Similar analyses of eight one-step-selected mutants did not reveal any base change in the gyrA and gyrB QRDRs. These results suggest that in M. hominis, like in other bacterial species, a gyrA mutation at Ser-83 is associated with fluoroquinolone resistance.
Bebear
C M
CM
Laboratoire de Bactériologie, Université de Bordeaux II, France. cbebear.@labbebear.u-bordeaux2.fr
Bové
J M
JM
Bebear
C
C
Renaudin
J
J
D000595:Amino Acid Sequence; D000890:Anti-Infective Agents / Q000494:pharmacology*; D001483:Base Sequence; D027081:DNA Gyrase; D004250:DNA Topoisomerases, Type II / Q000235:genetics; D004352:Drug Resistance, Microbial / Q000235:genetics; D024841:Fluoroquinolones; D008969:Molecular Sequence Data; D009154:Mutation; D019535:Mycoplasma hominis / Q000235:genetics* / Q000302:isolation & purification; D016133:Polymerase Chain Reaction
D000890:Anti-Infective Agents; D024841:Fluoroquinolones; D027081:DNA Gyrase; D004250:DNA Topoisomerases, Type II