Invasive fungal infections due to Candida species are a major cause of morbidity and mortality. Timely diagnosis and appropriate antifungal therapy are critical for patient management. Unfortunately, there are relatively few drug classes available for therapy and they are being compromised by drug resistance. The echinocandins are important antifungal agents for the treatment of patients with Candida infections. However, therapeutic failures are increasingly being reported especially with C. glabrata, which is a leading cause of disseminated candidiasis. Of the major Candida species, echinocandin resistance remains relatively uncommon. Yet, this is not the case for C. glabrata, where resistance now exceeds 13% in certain high-risk centers. It is well- established that clinical echinocandin drug resistance resulting in therapeutic failure is due to amino acid substitutions in highly conserved hot-spot regions of the Fks subunits of glucan synthase. There is a critical need to understand the cellular factors underlying the emergence of Fks-mediated echinocandin resistance. The novel hypothesis being explored in this proposal is that echinocandin resistance in C. glabrata is promoted by cellular factors that stabilize cells in response to drug by creating an unanticipated drug tolerant cell population, which ultimately escapes drug action by the formation of characteristic fks mutations. This hypothesis is supported by pharmacodynamic studies in mice indicating that echinocandin drug therapy at a standard dosage (human equivalent) results in drug tolerant or persistent cell populations. Such behavior is inconsistent with echinocandin drugs as presumed fungicidal agents. Rather, the in vivo data suggests that the echinocandin drugs behave as fungistatic agents at a standard dosage. It is hypothesized that in vivo cells become temporally drug- tolerant by inducing a variety of cellular compensatory mechanisms in response to cell wall stress due to echinocandin action. Cellular and genetic factors promote selection of drug resistant variants with mutations in FKS genes from high burden populations of drug tolerant persistor cells. To better understand echinocandin resistance in C. glabrata, a range of cellular factors will be examined in in vitro and in vivo models for their role in emergence of Fks-mediated echinocandin resistance. Specifically, the importance of compensatory cell wall stress responses, decreased DNA repair, azole resistance, serum, and potential novel genes/pathways will be evaluated using appropriate mutants, along with known inhibitors of these pathways. This work will exploit engineered isogenic mutant strains and a unique collection of serial genetically-matched susceptible and fks-resistant clinical isolates of C. glabrata. These latter isolates will be profiled for changes in the genome and transcriptome for the first time to assess the importance of known mechanisms and elucidate potential new genetic incites underlying resistance emergence. Our detailed molecular studies of echinocandin resistance with clinical isolates over the past decade provide a strong foundation to better understand the molecular basis underlying the emergence of echinocandin resistance in C. glabrata. It is anticipated that this information will provide important new insights and potential intervention strategies to overcome and/or prevent the emergence of echinocandin resistance.

Public Health Relevance

Invasive fungal infections are a significant cause of morbidity and mortality in immunocompromised patients, and treatment options are limited. The echinocandins are an important antifungal class for primary therapy but emerging resistance threatens their effectiveness. A greater understanding of factors contributing to resistance emergence is important to develop new strategies to overcome and/or prevent drug resistance.

National Institute of Health (NIH)
Research Project (R01)
Project #
Application #
Study Section
Drug Discovery and Mechanisms of Antimicrobial Resistance Study Section (DDR)
Program Officer
Duncan, Rory A
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Rutgers University
Internal Medicine/Medicine
Schools of Medicine
United States
Zip Code
Zhao, Yanan; Nagasaki, Yoji; Kordalewska, Milena et al. (2016) Rapid detection of FKS-associated echinocandin resistance in Candida glabrata. Antimicrob Agents Chemother :
Healey, Kelley R; Zhao, Yanan; Perez, Winder B et al. (2016) Prevalent mutator genotype identified in fungal pathogen Candida glabrata promotes multi-drug resistance. Nat Commun 7:11128
Huang, Wei; Liao, Guojian; Baker, Gregory M et al. (2016) Lipid Flippase Subunit Cdc50 Mediates Drug Resistance and Virulence in Cryptococcus neoformans. MBio 7:
Domán, Marianna; Kovács, Renátó; Perlin, David S et al. (2015) Dose escalation studies with caspofungin against Candida glabrata. J Med Microbiol 64:998-1007
Perlin, David S (2015) Echinocandin Resistance in Candida. Clin Infect Dis 61 Suppl 6:S612-7
Dudiuk, Catiana; Gamarra, Soledad; Jimenez-Ortigosa, Cristina et al. (2015) Quick Detection of FKS1 Mutations Responsible for Clinical Echinocandin Resistance in Candida albicans. J Clin Microbiol 53:2037-41
Perlin, David S (2015) Mechanisms of echinocandin antifungal drug resistance. Ann N Y Acad Sci 1354:1-11
Jensen, Rasmus Hare; Astvad, Karen Marie Thyssen; Silva, Luis Vale et al. (2015) Stepwise emergence of azole, echinocandin and amphotericin B multidrug resistance in vivo in Candida albicans orchestrated by multiple genetic alterations. J Antimicrob Chemother 70:2551-5
Cowen, Leah E; Sanglard, Dominique; Howard, Susan J et al. (2015) Mechanisms of Antifungal Drug Resistance. Cold Spring Harb Perspect Med 5:a019752
Espinel-Ingroff, A; Alvarez-Fernandez, M; Cantón, E et al. (2015) Multicenter study of epidemiological cutoff values and detection of resistance in Candida spp. to anidulafungin, caspofungin, and micafungin using the Sensititre YeastOne colorimetric method. Antimicrob Agents Chemother 59:6725-32

Showing the most recent 10 out of 15 publications