Candida Tropicalis Multilocus Sequence Typing And Its Clinical Significance

Objective:To analysis the relationship between38 strains of C.tropicalis from vulvovaginal candidasis by Using the MLST method;to compare the susceptibility of C.tropicalis to common antifungal agents in vitro,to examine the secretion of lipase,phospholipase and hemolytic of C.tropicalis andthe expression of common resistance genes in C.tropicalis.Methoes: We Sequenced the 6 alleles of C.tropicalis,compared them with C.tropicalis MLST database and obtained diploid sequence types(DST).We Grouped the DST by using e BRUST software and constructed the phylogenetic tree by using UPGMA method.Antifungal susceptibility test was detected in 38 strains of C.tropicalis by using broth dilution method.The lipase,phospholipase and hemolytic of C.Tropicalis were deteceted by using plate test.The expression level of CDR1,CDR2,ERG11 and ERG family(include ERG1、ERG3、ERG6、ERG9 and ERG11)were detected byusing real time fluorescent quantitative polymerase chain reaction.Result:We obtained 30 DSTs and 18 cladesfrom 38 strains of C.tropicalis,of which 14 new DSTs,11 new alleles and 27 DSTs are singleton.The minimum inhibitory concentration of Anidulafungin,caspofungin,micafungin and fluconazole,miconazole and amphotericin B,sulconazole,oriconazole,itraconazole,clotrimazole,terconazole,flucytosine,terbinafine and nystatin for C.Tropicalis were :0.030μg/ml、0.015μg/ml、0.500μg/ml、1.000μg/ml、2.000μg/ml、0.125μg/ml、0.250μg/ml、0.250μg/ml、0.250μg/ml、0.250μg/ml、256.000μg/ml and 4.000μg/ml,respectively.ll the strains were able to produce esterase and hemolysin,the positive rate were 100%,the positive rate of phospholipase activity was 76.3%.In the experiment of resistance genes,the smaller △CT value,the higher the amount of gene expression.The antifungal resistance genes expression levels in clade11 and clade14 strains were higher than other clades.Conclusion:The variation of multilocus sequence typing of C.tropicalis was larger and the genetic distance between strains was far.C.tropicalis is generally resistant to terbinafine,C.tropicalis were sensitive to most of the commonly used antifungal agents,and there are very few resistant strains.The geometric ratios of C.tropicalis to 14 common antifungal agents were higher than those of C.albicans.All strains were able to produce esterase and hemolytic activity,and most of the strainsshowed positive phospholipase activity.In this study,the high expression of resistance genes did not cause drug resistance.