Isolation of cholesterol-dependent, multidrug-resistant Candida glabrata strains from blood cultures of a candidemia patient in Kuwait.

Abstract

BACKGROUND:

Candida 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.

METHODS:

Both 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.

RESULTS:

The 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).

CONCLUSION:

This 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.

• Authors: Ziauddin Khan, Suhail Ahmad, Leena Joseph, Khaled Al-Obaid
• Journal: BMC infectious diseases (BMC Infect Dis) Vol. 14 Pg. 188 (Apr 08 2014) ISSN: 1471-2334 [Electronic] England
• PMID: 24712485 (Publication Type: Journal Article)

Chemical References

• Antifungal Agents
• Cholesterol

Topics

• Antifungal Agents (pharmacology)
• Candida glabrata (drug effects, isolation & purification, metabolism)
• Candidemia (microbiology)
• Cholesterol (metabolism)
• Drug Resistance, Multiple, Fungal
• Humans
• Kuwait
• Microbial Sensitivity Tests