The use of azole antifungals, including fluconazole, for treatment and/or prophylaxis against infections caused by Candida albicans has resulted in a recent, dramatic increase in Candida strains that are resistant to antifungal drugs. This is true in oral candidiasis in AIDS patients, and has recently been documented in other immune compromised individuals including blood and marrow transplant recipients (BMT). In the past several years, the basic molecular mechanisms of azole resistance have been identified including the overexpression of the target enzyme and two types of efflux pump, and mutation in the target enzyme. Recent data from this laboratory and others has indicated that resistance is a whole cell response in which virulence determinants can have an effect on resistance, and resistance determinants can have an effect on these other virulence factors. This whole cell response includes a heterogeneous resistance (Het-R) phenotype identified in our laboratory, in which certain susceptible isolates are able to form small colonies on agar plates containing fluconazole. This Het-R phenotype may be correlated with the ability to induce true resistance in these strains, and is related to heterogeneous resistance in bacteria. The overall goal of this project is to develop an understanding of the whole cell response of C. albicans to azole antiflingals, including the Het-R phenotype.
The specific aims of this proposal are: 1) to characterize the interactions between resistance and virulence factors of C. albicans, 2) to characterize the transcriptional regulation associated with the whole cell response, and 3) to characterize this Het-R phenotype as a specific whole cell response. Antifungal drug resistance and susceptibility testing has become increasingly important as invasive candidiasis has become a leading cause of nosocomial infections worldwide. The analyses outlined in this proposal will define some of the many responses of a cell to azole antifungal drugs, thus providing us with information critical to the development of effective strategies to prevent, diagnose or treat fungal infections.

Agency
National Institute of Health (NIH)
Institute
National Institute of Dental & Craniofacial Research (NIDCR)
Type
Research Project (R01)
Project #
5R01DE014161-03
Application #
6634713
Study Section
Special Emphasis Panel (ZRG1-AARR-3 (01))
Program Officer
Nokta, Mostafa A
Project Start
2001-04-01
Project End
2005-02-28
Budget Start
2003-03-01
Budget End
2004-02-29
Support Year
3
Fiscal Year
2003
Total Cost
$353,558
Indirect Cost
Name
Seattle Biomedical Research Institute
Department
Type
DUNS #
070967955
City
Seattle
State
WA
Country
United States
Zip Code
98109
Bhattacharya, Somanon; Esquivel, Brooke D; White, Theodore C (2018) Overexpression or Deletion of Ergosterol Biosynthesis Genes Alters Doubling Time, Response to Stress Agents, and Drug Susceptibility in Saccharomyces cerevisiae. MBio 9:
Zavrel, Martin; White, Theodore C (2015) Medically important fungi respond to azole drugs: an update. Future Microbiol 10:1355-73
Esquivel, Brooke D; Smith, Adam R; Zavrel, Martin et al. (2015) Azole drug import into the pathogenic fungus Aspergillus fumigatus. Antimicrob Agents Chemother 59:3390-8
Zavrel, Martin; Hoot, Sam J; White, Theodore C (2013) Comparison of sterol import under aerobic and anaerobic conditions in three fungal species, Candida albicans, Candida glabrata, and Saccharomyces cerevisiae. Eukaryot Cell 12:725-38
Brown, Gordon D; Denning, David W; Gow, Neil A R et al. (2012) Hidden killers: human fungal infections. Sci Transl Med 4:165rv13
Hoot, Samantha J; Smith, Adam R; Brown, Ryan P et al. (2011) An A643V amino acid substitution in Upc2p contributes to azole resistance in well-characterized clinical isolates of Candida albicans. Antimicrob Agents Chemother 55:940-2
Hoot, Samantha J; Brown, Ryan P; Oliver, Brian G et al. (2010) The UPC2 promoter in Candida albicans contains two cis-acting elements that bind directly to Upc2p, resulting in transcriptional autoregulation. Eukaryot Cell 9:1354-62
Mansfield, Bryce E; Oltean, Hanna N; Oliver, Brian G et al. (2010) Azole drugs are imported by facilitated diffusion in Candida albicans and other pathogenic fungi. PLoS Pathog 6:e1001126
Marie, Chelsea; White, Theodore C (2009) Genetic Basis of Antifungal Drug Resistance. Curr Fungal Infect Rep 3:163-169
Richards, Theresa S; Oliver, Brian G; White, Theodore C (2008) Micafungin activity against Candida albicans with diverse azole resistance phenotypes. J Antimicrob Chemother 62:349-55

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