Genetic Dissection of Azole Resistance Mechanisms in Candida albicans and Their Validation in a Mouse Model of Disseminated Infection
| Autor: | Alix T. Coste, Donna M. MacCallum, Dominique Sanglard, Frank C. Odds, Mette D. Jacobsen, Françoise Ischer |
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| Rok vydání: | 2010 |
| Předmět: |
Antifungal Agents
Genes Fungal Microbial Sensitivity Tests Drug resistance In Vitro Techniques Biology medicine.disease_cause Microbiology Fungal Proteins Mice Drug Resistance Fungal Candida albicans medicine Animals Humans Experimental Therapeutics Pharmacology (medical) Allele DNA Fungal Fluconazole DNA Primers Pharmacology chemistry.chemical_classification Genetics Mice Inbred BALB C Mutation Base Sequence Candidiasis Fungal genetics Membrane Transport Proteins biology.organism_classification Corpus albicans Disease Models Animal Infectious Diseases chemistry Azole Female Genetic Engineering medicine.drug |
| Zdroj: | Antimicrobial Agents and Chemotherapy. 54:1476-1483 |
| ISSN: | 1098-6596 0066-4804 |
| DOI: | 10.1128/aac.01645-09 |
| Popis: | Principal mechanisms of resistance to azole antifungals include the upregulation of multidrug transporters and the modification of the target enzyme, a cytochrome P450 (Erg11) involved in the 14α-demethylation of ergosterol. These mechanisms are often combined in azole-resistant Candida albicans isolates recovered from patients. However, the precise contributions of individual mechanisms to C. albicans resistance to specific azoles have been difficult to establish because of the technical difficulties in the genetic manipulation of this diploid species. Recent advances have made genetic manipulations easier, and we therefore undertook the genetic dissection of resistance mechanisms in an azole-resistant clinical isolate. This isolate (DSY296) upregulates the multidrug transporter genes CDR1 and CDR2 and has acquired a G464S substitution in both ERG11 alleles. In DSY296, inactivation of TAC1 , a transcription factor containing a gain-of-function mutation, followed by sequential replacement of ERG11 mutant alleles with wild-type alleles, restored azole susceptibility to the levels measured for a parent azole-susceptible isolate (DSY294). These sequential genetic manipulations not only demonstrated that these two resistance mechanisms were those responsible for the development of resistance in DSY296 but also indicated that the quantitative level of resistance as measured in vitro by MIC determinations was a function of the number of genetic resistance mechanisms operating in any strain. The engineered strains were also tested for their responses to fluconazole treatment in a novel 3-day model of invasive C. albicans infection of mice. Fifty percent effective doses (ED 50 s) of fluconazole were highest for DSY296 and decreased proportionally with the sequential removal of each resistance mechanism. However, while the fold differences in ED 50 were proportional to the fold differences in MICs, their magnitude was lower than that measured in vitro and depended on the specific resistance mechanism operating. |
| Databáze: | OpenAIRE |
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