title: Molecular mechanisms associated with Fluconazole resistance in clinical Candida albicans isolates from India.
abstract: Resistance to azole antifungals is a significant problem in Candida albicans. An understanding of resistance at molecular level is essential for the development of strategies to tackle resistance and rationale design of newer antifungals and target-based molecular approaches. This study presents the first evaluation of molecular mechanisms associated with fluconazole resistance in clinical C.albicans isolates from India. Target site (ERG11) alterations were determined by DNA sequencing, whereas real-time PCRs were performed to quantify target and efflux pump genes (CDR1, CDR2, MDR1) in 87 [Fluconazole susceptible (n = 30), susceptible-dose dependent (n = 30) and resistant (n = 27)] C.albicans isolates. Cross-resistance to fluconazole, ketoconazole and itraconazole was observed in 74.1% isolates. Six amino acid substitutions were identified, including 4 (E116D, F145L, E226D, I437V) previously reported ones and 2 (P406L, Q474H) new ones. CDR1 over-expression was seen in 77.7% resistant isolates. CDR2 was exclusively expressed with CDR1 and their concomitant over-expression was associated with azole cross-resistance. MDR1 and ERG11 over-expression did not seem to be associated with resistance. Our results show that drug efflux mediated by Adenosine-5'-triphosphate (ATP)-binding cassette transporters, especially CDR1 is the predominant mechanism of fluconazole resistance and azole cross-resistance in C. albicans and indicate the need for research directed towards developing strategies to tackle efflux mediated resistance to salvage azoles.
authors.affiliation: National AIDS Research Institute, Pune, Maharashtra, India.
authors.forename: Arati
authors.initials: A
authors.lastname: Mane
authors.affiliation: National AIDS Research Institute, Pune, Maharashtra, India.
authors.forename: Pallavi
authors.initials: P
authors.lastname: Vidhate
authors.affiliation: National AIDS Research Institute, Pune, Maharashtra, India.
authors.forename: Chanchal
authors.initials: C
authors.lastname: Kusro
authors.affiliation: Savitribai Phule Pune University (Formerly University of Pune), Bioinformatics Centre, Pune, Maharashtra, India.
authors.forename: Vaishali
authors.initials: V
authors.lastname: Waman
authors.affiliation: National AIDS Research Institute, Pune, Maharashtra, India.
authors.forename: Vandana
authors.initials: V
authors.lastname: Saxena
authors.affiliation: Savitribai Phule Pune University (Formerly University of Pune), Bioinformatics Centre, Pune, Maharashtra, India.
authors.forename: Urmila
authors.initials: U
authors.lastname: Kulkarni-Kale
authors.affiliation: National AIDS Research Institute, Pune, Maharashtra, India.
authors.forename: Arun
authors.initials: A
authors.lastname: Risbud
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D000935:Antifungal Agents / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D002177:Candidiasis / Q000188:drug therapy / Q000382:microbiology*; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics* / Q000378:metabolism; D004271:DNA, Fungal / Q000302:isolation & purification; D025141:Drug Resistance, Fungal / Q000235:genetics*; D015725:Fluconazole / Q000494:pharmacology*; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism*; D005800:Genes, Fungal; D006801:Humans; D007194:India; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
chemical_list: D018528:ATP-Binding Cassette Transporters; D000935:Antifungal Agents; C094693:CDR1 protein, Candida albicans; D004271:DNA, Fungal; D005656:Fungal Proteins; D026901:Membrane Transport Proteins; C465525:cytochrome P-450 CYP51, Candida albicans; D015725:Fluconazole; D003577:Cytochrome P-450 Enzyme System
keywords: Candida albicans; ERG11 mutations; Fluconazole resistance; drug efflux