| Kyeong Min Lee | 2 Articles |
Objectives
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. Methods 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. Results 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). Conclusion 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>. Citations
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Objectives
<i>Candida glabrata</i> has become one of the most common causes of <i>Candida</i> bloodstream infections worldwide. Some strains of <i>C. glabrata</i> may be intermediately resistant to all azoles. The several possible mechanisms of azole resistance have been reported previously, but the exact resistant mechanism is not clear. In this study, we identified differentially expressed genes (DEGs) of fluconazole-resistant <i>C. glabrata</i> and compared the gene expression of fluconazole-resistant strains with that of fluconazole-susceptible strains to identify gene corresponding to fluconazole resistance. Methods Using antifungal susceptibility test, several <i>C. glabrata</i> strains were selected and used for further study. The expression of <i>CgCDR1</i> and <i>CgCDR2</i> genes was investigated by slot hybridization against fluconazole-susceptible, -resistant, and resistant-induced strains. In addition, <i>ERG3</i> and <i>ERG11</i> genes were sequenced to analyze DNA base substitution. DEGs were identified by reverse transcription-polymerase chain reaction using DEG kit composed of 120 random primers. Results In slot hybridization, <i>CgCDR1</i> gene was expressed more than <i>CgCDR2</i> gene in resistant strains. Though base substitution of <i>ERG11</i> and <i>ERG3</i> genes was observed in several base sequences, just one amino acid change was identified in resistant strain. In the results of reverse transcription-polymerase chain reaction, 44 genes were upregulated and 34 genes were downregulated. Among them, adenosine triphosphate-binding cassette transporter-related genes, fatty acid desaturase, lyase, and hypothetical protein genes were upregulated and aldehyde dehydrogenase, oxidoreductase, and prohibitin-like protein genes were downregulated. Other DEGs were also identified. Conclusion This study showed that <i>CgCDR1</i> gene was more closely related to fluconazole resistance of <i>C. glabrata</i> than <i>CgCDR2</i> gene. In addition, several other genes related with fluconazole resistance of <i>C. glabrata</i> were identified. Citations
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