title: Resistance reversal induced by a combination of fluconazole and tacrolimus (FK506) in Candida glabrata.
abstract: There is an increasing concern about Candida glabrata due to its high isolation frequency in candidiasis recently and notorious drug resistance to fluconazole. Drug combination is one effective approach to counteract drug resistance. This study aimed to test whether a combination of fluconazole and tacrolimus (FK506) had a synergistic effect on C. glabrata, and to seek the potential mechanisms underlying the synergistic effects. In vitro effects of fluconazole and FK506 against C. glabrata with different susceptibilities were investigated by a chequerboard method and a time-kill curve method. The mechanistic studies against the resistant C. glabrata were performed from two aspects: quantification of expression levels of fluconazole resistance genes (ERG11, CDR1, PDH1 and SNQ2) by real-time quantitative PCR and functional assays of drug efflux pumps. The addition of FK506 resulted in a decrease in the MIC of fluconazole from 32 to 8 µg ml(-1) against the dose-dependent susceptible C. glabrata, and from 256 to 16 µg ml(-1) against the resistant C. glabrata, respectively. The synergy was further confirmed by the time-kill assay. The expression levels of the ERG11 and SNQ2 genes were significantly downregulated after exposure to the drug combination, whereas that of the CDR1 gene was significantly upregulated, and no significant change in expression of PDH1 gene was observed. Flow cytometric assays showed that FK506 reduced the efflux of fluconazole. Tacrolimus enhanced the susceptibility of fluconazole against resistant C. glabrata by reducing the expression levels of the ERG11 and SNQ2 genes and inhibiting fluconazole efflux.
authors.affiliation: Department of Pharmacy, Shandong Tumor Hospital, Jinan, 250117, PR China.|School of Pharmaceutical Sciences, Shandong University, Jinan, 250012, Shandong Province, PR China.
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.affiliation: Department of Pharmacy, Zibo Central Hospital, Zibo, 255000, Shandong Province, PR China.
authors.forename: Zuozhong
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Department of Respiratory Medicine, Qianfoshan Hospital Affiliated to Shandong University, Jinan, 250014, Shandong Province, PR China.
authors.forename: Caiqing
authors.initials: C
authors.lastname: Zhang
authors.affiliation: School of Pharmaceutical Sciences, Shandong University, Jinan, 250012, Shandong Province, PR China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Department of Pharmacy, Jinan Central Hospital Affiliated to Shandong University, Jinan, 250013, Shandong Province, PR China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Pharmacy, Qianfoshan Hospital Affiliated to Shandong University, Jinan, 250014, Shandong Province, PR China.
authors.forename: Shujuan
authors.initials: S
authors.lastname: Sun
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D001692:Biological Transport / Q000187:drug effects; D041221:Candida glabrata / Q000187:drug effects*; D025141:Drug Resistance, Fungal; D004357:Drug Synergism; D005434:Flow Cytometry; D015725:Fluconazole / Q000494:pharmacology*; D005656:Fungal Proteins / Q000096:biosynthesis / Q000235:genetics; D020869:Gene Expression Profiling; D006801:Humans; D008826:Microbial Sensitivity Tests; D012331:RNA, Fungal / Q000032:analysis / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D016559:Tacrolimus / Q000494:pharmacology*
chemical_list: D000935:Antifungal Agents; D005656:Fungal Proteins; D012331:RNA, Fungal; D015725:Fluconazole; D016559:Tacrolimus