Abstract
Purpose::
This study aimed to characterize mutations in gyrA, gyrB, parC and parE of S. epidermidis isolates and to correlate the effects of mutations or combinations of mutations within these genes with fluoroquinolone MICs.
Methods::
One-hundred and forty isolates were collected from the conjunctival sac of 140 eyes of 130 patients who were scheduled for intraocular surgery at National Tokyo Medical Center. MICs for levofloxacin, gatifloxacin, moxifloxacin and oxacllin were determined by the agar dilution method. The nucleotide sequence of quinolone resistance-determining regions was characterized using the amplified gyrA, gyrB, parC and parE gene of those strains by PCR method. All isolates were screened for the presence of the mecA genes by PCR.
Results::
The MIC values (microgram/ml) ranged from 0.1 to 25 for levofloxacin, 0.05 to 12.5 for gatifloxacin and < or = 0.025 to 12.5 for moxifloxacin. All isolates could be categorized in five types based on fluoroquinolone and oxacllin susceptibility. Both qinolone-resistant MSSE and MRSE had mutations in either or both the gyrA (located at codons 84 and 88) and parC (located at codons 80 and 84) genes.
Conclusions::
The simultaneous presence of gyrA and parC alterations was associated with a high level of fluoroquinolone resistance in the clinical isolates of S. epidermidis.
Keywords: antibiotics/antifungals/antiparasitics • gene/expression