| Sunok Park | 1 Article |
<b>Objectives</b><br/>
This study investigated the fluoroquinolone-resistant mechanism of 56 clinical cases of <i>A baumannii</i> infection from 23 non-tertiary hospitals, collected between 2004 and 2006.<br/><b>Methods</b><br/>
Susceptibility testing was performed by broth microdilution and Epsilometer test. Analyses of quinolone resistance-determining region (QRDR) were done by sequencing. The activity of the efflux pump was measured using inhibitors.<br/><b>Results</b><br/>
The sequences from selected 56 isolates were divided into seven groups (I-VII) on the basis of mutations in <i>gyrA</i> (S83L), <i>parC</i> (S80L, S80W and S84K) and <i>gyrB</i> (containing the novel mutations E679D, D644Y and A677V). The 27 isolates with triple mutations in <i>gyrA, gyrB</i> and <i>parC</i> (groups IV-VII) showed higher levels of resistance to ciprofloxacin (minimal inhibitory concentration [MIC] of 16-256 μg/mL) than the 26 isolates with double mutations in <i>gyrA</i> and <i>parC</i> (groups II and III, MIC of 8-64 μ g/mL; <i>p</i> < 0.05). Alterations in the efflux pump were observed in four isolates with the <i>parC</i> S80L mutation (group II) or E84K mutation (group VII), but no effect was observed in an isolate with the <i>parC</i> S80 W mutation (group III).<br/><b>Conclusion</b><br/>
These results suggest that triple mutations in clinical isolates of <i>A baumannii</i> contribute to the development of high levels of resistance to fluoroquinolones and that mutations in <i>parC</i> S80L or E84K (groups II and VII) may contribute to alterations in efflux pump activity in <i>A baumannii</i>.
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