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KMID : 0981820090290020127
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Korean Journal of Laboratory Medicine
2009 Volume.29 No. 2 p.127 ~ p.134
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Species-Specific Differences in Rhodamine 6G Accumulation of Candida Isolates Detected by Flow Cytometric Analysis
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Moon Chang-Jin
Shin Myung-Geun
Kee Seung-Jung
Shin Jong-Hee
Suh Soon-Pal
Ryang Dong-Wook
Kim Da-Woon
Kim Soo-Hyun
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Abstract
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Background : Fluorescent dye Rhodamine 6G (R6G) is a substrate of multidrug resistance pumps and its accumulation is reduced in some azole-resistant Candida isolates with the upregulation of multidrug efflux transporter genes. Despite reports on species-specific differences in azole susceptibility in various Candida species, only a few studies have been reported on the R6G accumulation among clinical isolates of Candida species. In this study, we compared R6G accumulation between six different Candida species.
Methods : The intracellular accumulation of R6G and minimal inhibitory concentrations (MICs) of three triazole agents were investigated in 48 strains of six Candida species (14 C. albicans, 9 C. tropicalis, 8 C. glabrata, 8 C. krusei, 7 C. parapsilosis, and 2 C.haemulonii ). R6G accumulation was measured by using flow cytometry and the geometric mean of the fluorescence intensity (GMF) was used to compare the accumulation between the Candida isolates.
Results : The GMF values for the C. tropicalis, C. albicans, C. krusei, C. parapsilosis, and C. glabrata isolates were 167.3±18.5, 126.9±6.6, 88.5±18.5, 50.8±7.0, and 38.1±3.9, respectively. C. glabrata had a significantly lower mean GMF than all the other Candida species (P<0.05). While some Candida strains with trailing growth phenomenon and increased fluconazole MIC did not have a reduced GMF, three Candida strains with increased MICs to all three triazole agents had a reduced GMF.
Conclusions : This study found species-specific differences in R6G accumulation in Candida. In addition, the intracellular R6G accumulation can be used to investigate the drug efflux mechanism in azole-resistant Candida strains.
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KEYWORD
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Candida, Flow cytometry, Rhodamine 6G, Azole resistance, Mechanism
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