Abstract
BackgroundCandida glabrata has emerged as an important human pathogen associated with systemic and mucosal infections. Here, we describe isolation of two cholesterol-dependent Candida glabrata strains from a candidemia patient which failed to grow on the media devoid of a cholesterol source.MethodsBoth the isolates were recovered from BACTEC Plus Aerobic/F blood culture bottles of a candidemic patient. Since these isolates failed to grow on Sabouraud dextrose agar, Mueller-Hinton agar and RPMI 1640 agar media, their definitive identification required PCR sequencing of the internally transcribed spacer (ITS)1 and ITS2 regions of rDNA and the D1/D2 region sequences within 26S rRNA gene. The cholesterol auxotrophy was determined by their ability to grow on media containing a cholesterol source. The minimum inhibitory concentrations (MICs) to antifungal agents were determined by Etest.ResultsThe identity of the isolates was confirmed by sequencing of the ITS1 and ITS2 regions of rDNA and the D1/D2 region sequences within 26S rRNA gene and also by matrix-assisted laser desorption and ionization–time-of-flight mass spectrometry with 99.9% confidence value. Both the isolates showed good growth only when media were supplemented with cholesterol, oxbile or blood. Additionally, these isolates were resistant to amphotericin B (MIC ≥32 μg/ml), fluconazole (MIC ≥256 μg/ml), voriconazole (MIC ≥32 μg/ml), itraconazole (MIC ≥32 μg/ml), and posaconazole (MIC ≥32 μg/ml), but susceptible to caspofungin (MIC range 0.064 to 0.19 μg/ml).ConclusionThis appears to be the first report on isolation of cholesterol-dependent strains of C. glabrata from a candidemia patient exhibiting resistance to azoles and amphotericin B. Further, the report demonstrates that induction of cholesterol/sterol auxotrophy is associated with resistance to antifungal drugs targeting ergosterol biosynthesis. These observations may have therapeutic implications for the treatment of infections caused by such C. glabrata strains.
Highlights
Candida glabrata has emerged as an important human pathogen associated with systemic and mucosal infections
C. glabrata strains requiring exogenous cholesterol for growth have been recovered from non-blood specimens and were found to be resistant to antifungal drugs that act on ergosterol biosynthesis [11,12]
Two cholesterol-dependent C. glabrata strains isolated from the blood of a candidemic patient are described
Summary
Candida glabrata has emerged as an important human pathogen associated with systemic and mucosal infections. We describe isolation of two cholesterol-dependent Candida glabrata strains from a candidemia patient which failed to grow on the media devoid of a cholesterol source. Candida glabrata has emerged as the second most important yeast associated with mucosal and systemic infections in critically ill patients in some tertiary care hospitals in North America [1]. There are multiple mechanisms that impart resistance against azoles. These include alterations in ERG11 gene that encodes for 14- α-methyl sterol demethylase in ergosterol biosynthesis and/or upregulation of efflux pumps encoded by CgCDR1 and CgCDR2 genes [2,3,4]. We describe the isolation of two C. glabrata strains from bloodstream of a candidemia patient which required exogenous cholesterol/sterol for growth in media that are routinely used in clinical mycology laboratories
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
