耐氟康唑白念珠菌临床株ERG11基因突变检测

目的 筛查耐氟康唑白念珠菌ERG11基因突变,探讨其与耐药的关系.方法 用柯玛嘉显色培养基和25S rDNA转座内含子保守区分型方法,收集鉴定白念珠菌临床株.联用微量稀释法和Rosco药敏纸片扩散法体外测定试验菌株对氟康唑的敏感性.以ERG11序列明确的白念珠菌标准耐药株ATCC 76615-19和达令顿株为质控,以标准敏感株C1b和临床敏感株02928为对照,分3段扩增临床耐药株ERG11基因并测序.结果 获得15株A型白念珠菌临床耐药株.ERG11基因测序共发现16处同义突变和11处错义突变.质控株突变与既往报道一致.敏感株共出现9处同义突变和3处错义突变G640A(E165K)、A945C(E266D)、G1609A/G(V488I).耐药临床株中的14株均出现2处共有的错义突变G487T(A114S)和T916C(Y257H),不伴其他突变;另1株出现8处同义突变和4处错义突变R541C(Y132H)、T495A(D116E)、A530C(K128T)、T1493A(F449Y),其中T1493A(F449Y)未见报道.结论不同来源的白念珠菌临床耐药株集中发生G487T(A114S)和T916C(Y257H)突变,暗示这2处突变极可能参与菌株耐药.耐药株可以发生T1493A(F449Y)突变.

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

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.