| Yeong Seon Lee | 6 Articles |
<b>Objectives</b><br/>
The proteomic analysis of voriconazole resistant <i>Candida glabrata</i> strain has not yet been investigated. In this study, differentially expressed proteins of intracellular and membrane fraction from voriconazole-susceptible, susceptible dose-dependent (S-DD), resistant <i>C. glabrata</i> strains were compared with each other and several proteins were identified.<br/><b>Methods</b><br/>
The proteins of intracellular and membrane were isolated by disrupting cells with glass bead and centrifugation from voriconazole susceptible, S-DD, and resistant <i>C. glabrata</i> strains. The abundance of expressed proteins was compared using two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis and proteins showing continuous twofold or more increase or reduction of expression in resistant strains compared to susceptible and S-DD strain were analyzed by liquid chromatography/mass spectrometry-mass spectrometry method.<br/><b>Results</b><br/>
Of 34 intracellular proteins, 15 proteins showed expression increase or reduction (twofold or more). The identified proteins included regulation, energy production, carbohydrate transport, amino acid transport, and various metabolism related proteins. The increase of expression of heat shock protein 70 was found. Among membrane proteins, 12, 31 proteins showed expression increase or decrease in the order of susceptible, S-DD, and resistant strains. This expression included carbohydrate metabolism, amino acid synthesis, and response to stress-related proteins. In membrane fractions, the change of expression of 10 heat shock proteins was observed, and 9 heat shock protein 70 (Hsp70) showed the reduction of expression.<br/><b>Conclusion</b><br/>
The expression of Hsp70 protein in membrane fraction is related to voriconazole resistant <i>C. glabrata</i> strains.
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<b>Objectives</b><br/>
To investigate the biofilm-forming related factors against MRSA bloodstream isolates and evaluates their clinical features and treatment outcomes by biofilm production.<br/><b>Methods</b><br/>
We collected 126 consecutive methicillin-resistant <i>Staphylococcus aureus</i> (MRSA) causing blood stream infections (BSIs) at 10 tertiary hospitals from 2007 to 2009. We investigated biofilm-forming ability using a microtiter plate assay, and molecular characteristics including multilocus sequence typing, staphylococcal cassette chromosome mec and accessory gene regulator types. We compared the clinical characteristics and outcomes of patients infected with biofilm-forming and non-biofilm-forming MRSA isolates.<br/><b>Results</b><br/>
Of the 126 samples, 86 (68.3%), including 5 strong level (OD<sub>570</sub> ≥ 1.0) and 81 weak level (0.2 ≤ OD<sub>570</sub> < 1.0), had biofilm-forming capacity. Detection of fibronectinbinding protein in biofilm-forming strains was significantly higher than biofilm non-forming ones (<i>p</i> = 0.001) and three enterotoxin genes (sec-seg-sei) islands had a high frequency regardless of biofilm production. However, biofilm-forming strains were more likely to be multidrug resistant (three or more non-β-lactam antibiotics) than biofilm non-forming ones [79.2% vs. 59.2%, <i>p</i> = 0.015, odds ratio (OR) 2.629, 95% confidence interval (CI) 1.92–5.81]. Clinical features of patients with BSIs caused by biofilm-forming MRSA strains were more likely to be hospital onset [77.9% vs. 60.0%, <i>p</i> = 0.024, OR 2.434, 95% CI 1.11–5.33) and more frequently occurred in patients with use of invasive devices [85.7% vs. 61.2%, <i>p</i> = 0.002, OR 3.879, 95% CI 1.61–8.97]. The other clinical features were compared with the clinical outcomes of the two groups and were not significant (<i>p</i> > 0.05).<br/><b>Conclusion</b><br/>
Biofilm-forming MRSA strains showed higher frequency of <i>fnbB</i> gene than biofilm non-forming ones and more incidence rates on particular genotypes. And, their patient's features were not significantly different between two groups in this study, except for several clinical factors.
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<b>Objectives</b><br/>
<i>Candida glabrata</i> is one of the most common causes of <i>Candida</i> bloodstream infections worldwide. Some isolates of <i>C glabrata </i>may be intermediately resistant to azoles, with some strains developing resistance during therapy or prophylaxis with fluconazole. In this study, we used a proteomic approach to identify differentially expressed proteins between fluconazoleresistant and -susceptible strains.<br/><b>Methods</b><br/>
Membrane and cellular proteins were extracted from fluconazolesusceptible and fluconazole-resistant <i>C glabrata </i>strains. Differentially expressed proteins were compared using two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis. Proteins with >1.5-fold difference in expression were identified by liquid chromatography tandem mass spectrometry (LC-MS/MS).<br/><b>Results</b><br/>
A total of 65 proteins were differentially expressed in the cellular and membrane fractions. Among the 39 cellular proteins, 11 were upregulated and 28 were downregulated in fluconazole-resistant strains in comparison with fluconazole-susceptible strains. In the membrane fraction, a total of 26 proteins were found, of which 19 were upregulated and seven were downregulated. A total of 31 proteins were identified by LC-MS/MS that are involved in glycolysis, carbohydrate transport, energy transfer, and other metabolic pathways. Heat shock proteins were identified in various spots.<br/><b>Conclusion</b><br/>
Heat shock and stress response proteins were upregulated in the membrane fraction of the fluconazole-resistant <i>C glabrata </i>strain. Compared with susceptible strains, fluconazole-resistant strains showed increased expression of membrane proteins and decreased expression of cellular proteins.
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<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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<b>Objectives</b><br/>
<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.<br/><b>Methods</b><br/>
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.<br/><b>Results</b><br/>
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.<br/><b>Conclusion</b><br/>
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.
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