Analysis Of ERG3 Gene Mutation In Resistance Of Candida

BackgroundIn recent years invasive fungal infections have increased obviously, Candida albicans accountsfor the first number of conditional pathogenic fungi isolated,however,there has been a hugeincreases in the frequency of non-albicans Candida krusei due to the use of antifungal agents.Candida albicans and Candida krusei have increased as a consequence of resistance to azoleantifungal agents.Therefore, researches on the mechanism of resistance in Candida albicans andCandida krusei have been highlighted.ObjectiveTo investigate the etiology features and relevant risk factors of invasive fungal infections fromclinically used abacterial body in hospital. To know the drug of azole antifungal agents ofsensitivity of Candida albicans and Candida krusei . To study the mechanism of azole antifungalagents resistance in clinical isolates of Candida albicans and Candida krusei, may be associatedwith the mutations in gene of ERG3.MethodsThe abacterial body fluid of invasive fungal infections during 2006 to 2010 from the clinicallaboratory of the Second Hospital of Shanxi Medical University were enrolled and analyzed.Theidentification of all isolates were confirmed by CHROMagar、CMA and API 20C AUX.A total of163 clinical isolates of Candida species were collected . So we can get 35 strains of azoleantifungal agents resistent and susceptible of Candida albicans and 20 strains of azole antifungalagents resistent and susceptible of Candida krusei respectively.ERG3 gene was amplified by PCRusing Candida albicans genomic DNA , and compared the DNA sequences of the PCR productsthrough BLAST softwares.Results(1) Most of 163 fungal isolates was Candida albicans(54.61%).Non-albicans Candidaaccounted for 42.94% and Aspergillus spp. was 2.45%. The analysis showed that sex, course ofdisease, temperature, prophylaxisly antifungal drugs using,immunosuppressants using, invasiveexamination and treatment, prognosis, sample originals were the independent risk factors forinvasive fungal infections.(2) Of the 35 Candida albicans, the rate of strains susceptible to 5-flucytosine andamphotericine B was 100%,the rate of strains resistant to itraconazole, voriconazole andfluconazole was 17.14%、11.43%、8.57%. Of the 20 Candida krusei, the rate of strains susceptibleto voriconazole and amphotericine B was 95%,the rate of strains resistant to 5-flucytosine, fluconazole and itraconazole was 20.00%、50.00%、45.00%. Candida albicans and Candida kruseihave the phenomenon of multiple drug resistance.(3) The comparison of ERG3 gene sequences identified mutations at 9 sites in Candidaalbicans strains.A17 of drug-resistant strain harbored 4 misssense mutations and 1 samesensemutations in ERG3,4 misssense mutations including I340L、V374G、P902L、V1076A respectively,the samesense mutation is 1080bp.The other strain harbored 5 samesense mutations, including602bp、795bp、969bp、1080bp、1110bp.ConclusionsMost of 163 fungal isolates was Candida albicans,but non- Candida albicans to rise espicallyCandida krusei.Although Candida albicans have resistance to azole antifungal agents ,but the rateof strains susceptible to itraconazole, fluconazole and voriconazole was 71.43%、85.72%、88.57%,so azole antifungal agents also useful drugs in clinical.The results suggest that missensemutations in ERG3 of Candida albicans have contribute to the mechanism of azole antifungalagents resistance,but the numble and pattern of those mutations have no any regular, thosemutations at the same time or at the different time should not be discounted.