Human Serum Potentiates the Expression of Genes Associated with Antifungal Drug Resistance in C. albicans Biofilms on Central Venous Catheters
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Candida albicans is a major agent of fungaemias and frequently causes systemic disease through seeded, blood stream dissemination. These infections, particularly common in hospitalized patients with central venous catheters (CVCs), appear to persevere due to biofilm reservoirs of the yeast that tend to develop on the device. Although it is known that candidal biofilms are intrinsically resistant to antifungals compared with their planktonic counterparts, there is a paucity of data on the expression of antifungal drug resistance genes (DRGs) in candidal biofilms in CVC reservoirs. Furthermore, notwithstanding the fact that CVCs are constantly bathed in human serum, there are no studies on the effect of the latter on the DRG expression in candidal biofilms. Hence, we developed in vitro biofilms of three different C. albicans strains on silicone CVC discs immersed in human serum and evaluated the temporal expression of nine antifungal DRGs. In an attempt to evaluate the effect of hyphal elements on DRG expression, we incorporated a hyphal mutant (HM) and its wild-type (WT) counterpart, as well as a fresh clinical isolate in the studies. Human serum significantly up-regulated DRG transcripts in Candida biofilms on CVCs, at different stages of biofilm growth, while the WT strain over-expressed more DRGs than the HM strain. Here, we report, for the first time, that both human serum and the hyphal elements of the yeast have a profound modulatory effect on DRG expression in C. albicans biofilms on CVCs.
KeywordsSerum Drug resistance genes C. albicans biofilms Central venous catheters
The authors are grateful to Mr. Shadow Yeung for statistical advice and Dr. Y H Samaranayake for his help with the manuscript writing. We thank Professor N. A. R. Gow (The University of Aberdeen, UK) for providing C. albicans SC5314 strain and its hyphal mutant HLC54). Two of the authors (M. H and S. V) would like to acknowledge the kind support of the Research Centre, College of Applied Medical Sciences and Deanship of Scientific Research at King Saud University.
Conflict of interest
No potential conflicts of interest were disclosed.
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