阴道白假丝酵母菌25SrDNA基因分型与药物敏感性的关系

摘要

Objective To investigate 25S rDNA genotype distribution of vaginal Candida albicans and its relationship with antifungal susceptibility. Methods A total of 954 isolates of Candida albicans were subjected to genotype analysis according to the presence and the size of transposable groupⅠintron in 25S rDNA with PCR; 156 isolates were enrolled to detect their antifungal susceptibility of 5 antifungal agents with the M27-A3 broth microdilution method. Results Totally 876 isolates were determined to be intronless genotype A (91.8%,876/954); 58 (6.1%, 58/954) and 20 isolates (2.1%, 20/954) were intron-containing genotype B and genotype C, respectively. The minimal inhibitory concentrations (MIC) of itraconazole and fluconazole against the intron-containing group were significantly higher than those of the intronless group (0.25 versus 0.125μg/ml, P<0.05;0.25 versus 0.125μg/ml, P<0.01), whereas the MIC of nystatin against the intron-containing group was lower than that of the intronless group (4 versus 8μg/ml, P<0.01). The resistance rate of Candida albicans to itraconazole of the intron-containing group was significantly higher than that of the intronless group [24% (19/78) versus 3% (2/78), P<0.01]. Cross-resistance analysis revealed 5 of the 21 (24%) itraconazole resistant isolates were cross-resistant to fluconazole ,and 5 of the 6 (5/6) fluconazole-resistant strains were cross-resistant to itraconazole. Besides, all the five strains simultaneously resistant to itraconazole and fluconazole belonged to the intron-containing group. Conclusion The presence of the transposable group Ⅰ intron in 25S rDNA of vaginal Candida albicans might be important in affecting itraconazole, fluconazole and nystatin susceptibility.%目的：探讨外阴阴道假丝酵母菌病患者阴道白假丝酵母菌分离株的25S rDNA基因型别分布特征，并分析不同基因型别阴道白假丝酵母菌的药物敏感性。方法根据阴道白假丝酵母菌25S rDNA基因编码区可转座Ⅰ型内含子的有无及大小，通过PCR技术对954株白假丝酵母菌进行基因分型。选取156株白假丝酵母菌，采用M27-A3微量肉汤稀释法测定其对伊曲康唑、氟康唑、咪康唑、克霉唑和制菌霉素5种抗真菌药物的敏感性。结果954株白假丝酵母菌分为3种基因型别，其中A型876株（91.8%，876/954）为不含内含子菌株，B型58株（6.1%，58/954）和C型20株（2.1%，20/954）为含内含子菌株。含内含子的白假丝酵母菌对伊曲康唑和氟康唑的最低抑菌浓度（MIC）值显著高于不含内含子者（伊曲康唑：0.25、0.125μg/ml，P<0.05；氟康唑：0.25、0.125μg/ml，P<0.01），对制霉菌素的MIC值显著低于不含内含子者（分别为4、8μg/ml，P<0.01）。含内含子的白假丝酵母菌对伊曲康唑的耐药率（24%，19/78）显著高于不含内含子者（3%，2/78；P<0.01）。21株伊曲康唑耐药株中有5株（24%，5/21）对氟康唑交叉耐药；6株氟康唑耐药株中有5株（5/6）对伊曲康唑交叉耐药；5株同时对伊曲康唑及氟康唑耐药的菌株均为含内含子菌株。结论25S rDNA基因编码区的可转座Ⅰ型内含子可能与阴道白假丝酵母菌对伊曲康唑、氟康唑及制霉菌素的药物敏感性有关。