Detection of ERG11 mutations in clinical isolates of Candida albicans resistant to fluconazole

Abstract

Objeetive To detect ERG11 gene mutations in clinical isolares of Candida albicans resistant to fluconazole.and discuss their relationship with formation of drug resistance.Methods Clinical specimens were collected.CHROMagar mediuln and amplification of the fragment spanning the conserved sequence of 25S rDNA including some transposable introns.were used to identify subtype Candida albicans isolates.FIuconazole sensitivity was detected in vitro through microdilution and Rosco tablets.The other three fragment of ERG11 gene were amplified and followed by sequencing with resistant type strain ATCC 76615-19 and Candida albicans Darlington strain with two sensitive isolates as controh.Results Fifteen resistant isolates of Candida albicans were found,all of which were type A.Sixteen silent mutations and 11 missense mutations were detected.Mutations in ATCC 76615-19 and Darlington strain were same with what had been reported.In the 2 sensitive strains.G640A(E165K),A945C(E266D)and G1609A/G(V488I)occurred,as well as the other 9 silent mutations.Only G487T(A114S)and T916C(Y257H)existed in each of 14 resistant isolates.In the other one resistant isolate,T541C(Y132H),T495A(D116E),A530C (K128T)and T1493A(F449Y)occurred Mong with 8 silent mutations.Conclusions The occurrence of G487T(A114S)and 1916C(Y257H)in 14 isolates from different sources suggested they may involve in fluconazole resistance.The novel mutation T1493A(F449Y)can appear in resistant isolves of Candida albicans. Key words: Candida albicans; Fluconazole; Drug resistance,fangal; Cytochrome p-450 enzyme system; Oxidoreductages; Fangal proteins; Mutation基金项目:国家自然科学基金资助项目(30471563)