Study On The Induction Of Drug-resistant Strains To Fluconazole Or Amphoterincin B In Vitro And Corresponding Molecular Mechanisms In The Candida Parapsilosis And The Candida Tropicalis

Objective:To test drug susceptibility of candidas against fluconazole oramphoterincin B, induce the fluconazole or amphoterincin B resistant strains of thecandida parapsilosis and the candida tropicalis in vitro and test the expressions of thedrug-resistant genes and discuss the Corresponding molecular mechanisms.Method: Fluconazole or amphoterincin B susceptibility was evaluated by a standardbroth microdilution method. Then we induced the resistant strains with fluconazole oramphoterincin B in vitro. The drug-resistant gene expression levels of the wild strainsand the resistant strains were measured by real-time fluorescence quantitative PCR.Result:The wild strains have CYP51A、CYP51B、CDR1、CDR2、MDR1、MDR2、Yap1、Shol mRNA expression at low level in the candida parapsilosis and the candidatropicalis.But the mRNA expression level of the CYP51A、CYP51B、CDR1、CDR2、MDR1、MDR2、Yap1、Shol was higher in the induced amphoterincin B resistant strainsthan the wild strains(P<0.05). The mRNA expression level of the CYP51A、CDR1、CDR2、MDR1、Yap1、Shol was higher in the induced fluconazole resistant strains thanthe wild strains(P<0.05).But the expression of Cyp51B and MDR2experienced nosignificant change during the induction of fluconazole resistant strains (P>0.05).Conclusion：The excessive expression of the CYP51A、CYP51B、CDR1、CDR2、MDR1、 MDR2、 Yap1、 Shol mRNA was associated with the resistance toamphoterincin B in the candida parapsilosis and the candida tropicalis strains. Theexcessive expression of the CYP51A、CDR1、CDR2、MDR1、Yap1、Shol mRNA wasassociated with the resistance to fluconazole in the candida parapsilosis and thecandida tropicalis strains. Aftering the contacting fluconazole or amphoterincin B fora long time the candida parapsilosis and the candida tropicalis can induce the keyenzyme gene in the synthesis of ergosterol，the efflux pump genes and the signaltransducing related genes expression leading to the resistance to the fluconazole or amphoterincin B.