25S rDNA genotype and antifungal susceptibility of vaginal Candida albicans / 中华妇产科杂志

ABSTRACT

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.