title: Expression Patterns of ABC Transporter Genes in Fluconazole-Resistant Candida glabrata.
abstract: Clinical management of fungal diseases is compromised by the emergence of antifungal drug resistance in fungi, which leads to elimination of available drug classes as treatment options. An understanding of antifungal resistance at molecular level is, therefore, essential for the development of strategies to combat the resistance. This study presents the assessment of molecular mechanisms associated with fluconazole resistance in clinical Candida glabrata isolates originated from Iran. Taking seven distinct fluconazole-resistant C. glabrata isolates, real-time PCRs were performed to evaluate the alternations in the regulation of the genes involved in drug efflux including CgCDR1, CgCDR2, CgSNQ2, and CgERG11. Gain-of-function (GOF) mutations in CgPDR1 alleles were determined by DNA sequencing. Cross-resistance to fluconazole, itraconazole, and voriconazole was observed in 2.5 % of the isolates. In the present study, six amino acid substitutions were identified in CgPdr1, among which W297R, T588A, and F575L were previously reported, whereas D243N, H576Y, and P915R are novel. CgCDR1 overexpression was observed in 57.1 % of resistant isolates. However, CgCDR2 was not co-expressed with CgCDR1. CgSNQ2 was upregulated in 71.4 % of the cases. CgERG11 overexpression does not seem to be associated with azole resistance, except for isolates that exhibited azole cross-resistance. The pattern of efflux pump gene upregulation was associated with GOF mutations observed in CgPDR1. These results showed that drug efflux mediated by adenosine-5-triphosphate (ATP)-binding cassette transporters, especially CgSNQ2 and CgCDR1, is the predominant mechanism of fluconazole resistance in Iranian isolates of C. glabrata. Since some novel GOF mutations were found here, this study also calls for research aimed at investigating other new GOF mutations to reveal the comprehensive understanding about efflux-mediated resistance to azole antifungal agents.
authors.affiliation: Student Research Committee, Mazandaran University of Medical Sciences, Sari, Iran.
authors.forename: Atefeh Abdollahi
authors.initials: AA
authors.lastname: Gohar
authors.affiliation: Invasive Fungi Research Centre, Mazandaran University of Medical Sciences, Sari, Iran.|Department of Medical Mycology and Parasitology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran.
authors.forename: Hamid
authors.initials: H
authors.lastname: Badali
authors.affiliation: Invasive Fungi Research Centre, Mazandaran University of Medical Sciences, Sari, Iran.|Department of Medical Mycology and Parasitology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran.
authors.forename: Tahereh
authors.initials: T
authors.lastname: Shokohi
authors.affiliation: Student Research Committee, Mazandaran University of Medical Sciences, Sari, Iran.|Iranian Social Security Organization, Mazandaran, Iran.
authors.forename: Mojtaba
authors.initials: M
authors.lastname: Nabili
authors.affiliation: Student Research Committee, Mazandaran University of Medical Sciences, Sari, Iran.|Department of Laboratory Sciences, School of Paramedicine/Infectious and Tropical Diseases Research Centre, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
authors.forename: Nasrin
authors.initials: N
authors.lastname: Amirrajab
authors.affiliation: Invasive Fungi Research Centre, Mazandaran University of Medical Sciences, Sari, Iran. moazeni.maryam@gmail.com.|Department of Medical Mycology and Parasitology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran. moazeni.maryam@gmail.com.
authors.forename: Maryam
authors.initials: M
authors.lastname: Moazeni
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis* / Q000235:genetics; D019943:Amino Acid Substitution; D000935:Antifungal Agents / Q000494:pharmacology*; D041221:Candida glabrata / Q000187:drug effects* / Q000201:enzymology* / Q000302:isolation & purification; D002177:Candidiasis / Q000382:microbiology; D025141:Drug Resistance, Fungal; D015725:Fluconazole / Q000494:pharmacology*; D020869:Gene Expression Profiling; D006801:Humans; D007492:Iran; D017964:Itraconazole / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D020125:Mutation, Missense; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D065819:Voriconazole / Q000494:pharmacology
chemical_list: D018528:ATP-Binding Cassette Transporters; D000935:Antifungal Agents; D017964:Itraconazole; D015725:Fluconazole; D065819:Voriconazole
keywords: Candida glabrata; CgPDR1 mutations; Drug efflux; Fluconazole resistance