Genotypic Analysis And Drug Susceptibility Tests Of 90 Candida Albicans Isolates Obtained From Clinical Specimens

Candida albicans is one of the normal floras in human bodies. It can be isolated from the samples in oral cavity, skin, intestine, vagina, anus et al, at the same time it is also the most important opportunity pathogen causing Candida infections. With the development of medical science, application of various new drugs, broad spectrum antibiotics, hormones and all kinds of vessels lead to high incidence of deep fungal infections which C.albicans are the leading cause. Therefore, it is of important significance to the diagnosis and genotyping of C. albicans infections in clinical and epidemiological research, the purpose of genotyping includes: (1) to trace the source of C. albicans infection, make clear the route of transmission, avoid prevalence of infection; (2) to determine the reason of repeated infections happened in one patient is either recurrence or re-infection; (3) to clear the relationship between certain strain of C. albicans and some clinical symptoms or diseases and find out the distinct pathogenesis; (4) to understand relationship between the occurrence of C. albicans infections and the genetic factors, as well as host susceptibility; (5) to study the differences between resistant and sensitive strains of C. albicans, particularly the relationships between phenotype and genotypes .In this study, the sensitive and specific polymerase chain reaction (PCR) was applied to amplify the target DNA fragment spanning the region of the transposable groupâ… intron of 25S rDNA of Candida albicans. The size of insertion segments of the intron in the 25S rDNA were detected by agarose gel electrophoresis. Genotype A which is wild type of C. albicans has no intron; genotype B and C contain 379bp of insertion segment, genotype E contains 379bp, 252bp and 341bp, genotype D belongs to C. Dubliniensis. The drug susceptibility tests were performed by ATB Fungus 3 tip to analyze the amphotericin B (AMB), fluconazole (FCA), itraconazole (ITR), 5-fiucytosine (5-FC), and voriconazole (VRC).Three genotypes in 90 strains of C. albicans isolated from clinical specimens have been identified. They are genotype A (44/90, 48.9%), genotype B (33/90, 36.7%) and genotype C (13/90,14.4%). None of 90 isolates presented the drug resistance to AMB. Both genotype B and C are susceptible to 5-FC. 95.5% of isolates genotype A were susceptible to 5-FC while 4.5% is resistant; 93.2% of genotype A, 90.9% of genotype B and 76.9% of genotype C are susceptible to FCA, respectively; 90.8% of genotype A is susceptible to ITR, 81.8% for genotype B and 76.9% for genotype C; 97.7% of genotype A is susceptible to VRC, 96.9% for genotype B and 92.3% for genotype C.C. albicans genotyping by PCR is convenient and rapid method with higher specificity and repeatability. Identifying the distinct drug-resistant spectrum in various genotypes of C. albicans facilitates the analysis of the hospital infections and research on fungal epidemiology and also promotes understanding the relationship between C. albicans infections and their drug resistance. It is helpful for clinical physicians to prescribe anti-fungal agents rationally and effectively monitor and control hospital infections of C. albicans.