侵袭性白色假丝酵母菌院内传播的分子机制研究

Molecular mechanism of nosocomial transmission of invasive Candida albicans

目的调查北京朝阳医院2000-2010年侵袭性白色假丝酵母菌感染的流行病学特点,研究侵袭性白色假丝酵母菌的遗传多样化和基因型分布,探讨其院内传播的分子机制。方法对82株侵袭性白色假丝酵母菌进行菌种收集统计;采用科玛嘉显色培养基(Chromagar)结合VITEK-2Compact YST卡进行菌种初筛鉴定;PCR扩增其CAI区微卫星序列;应用CAI区SSCP图谱和GeneScan相结合对侵袭性白色假丝酵母菌进行基因型的比较分析;药敏试验采用ATB FUNGUS 3系统和E-test对5种抗真菌药物进行MIC值测定。结果 2000-2010年朝阳医院血流感染病原菌共2320株,检出侵袭性假丝酵母菌148株,占6.4%,其中白色假丝酵母菌检出61株占41.22%,为假丝酵母菌属感染的首位;无菌体液病原菌4093株,检出侵袭性假丝酵母菌属253株,占6.2%,白色假丝酵母菌最多150株,占59.29%;临床独立来源的侵袭性白色假丝酵母菌82株,基于微卫星片段CAI区共有38种基因型;6例患者不同来源标本分离的白色假丝酵母菌基因型完全相同;侵袭性白色假丝酵母菌感染中ICU最高占52.44%,值得重视;侵袭性白色假丝酵母菌对5-氟胞嘧啶、两性霉素B、伏立康唑、泊沙康唑的敏感率均为100.00%;氟康唑为97.56%。结论白色假丝酵母菌仍然占侵袭性假丝酵母菌感染的首位,基因分型显示侵袭性白色假丝酵母菌呈多态性分布,发生侵袭的菌株基因型与定植的基因型有关。

OBJECTIVE To investigate epidemiological characteristics,diversity and genotyping distribution of invasive Candida albicans from 2000 to 2010 in Beijing Chaoyang Hospital,to investigate molecular mechanisms of nosocomial transmission of invasive C.albicans.METHODS A total of 82 strains of invasive C.albicans were collected,the identification of the strains was performed by Chromagar agar with vitek 2 compact YST card;the microsatellite sequences in stable genes CAI were amplified and genotyped by single-strand conformation polymorphisms（SSCP） of C.albicans’ microsatellite CAI combined with the GeneScan data for invasive C.albicans genotype comparative analysis.The determination of MIC of 5 drugs（5-fluorocytosine,amphotericin B,fluconazole,itraconazole,voriconazole） was performed by ATB FUNGUS 3 system.RESULTS From Jan 2000 to Dec 2010,of 2320 strains of pathogens causing bloodstream infections,there were 148（6.4%） strains of invasive Candida,among which C.albicans accounted for 41.22%（61 strains）,ranking the first place;a total of 4093 strains of pathogens were isolated from sterile fluids,among which invasive Candida were 253 strains（6.2%）,C.albicans accounted for 59.29%（150 strains）;of 82 independent strains,38 distinct CAI genotypes were identified by GeneScan analysis;the genotypes of C.albicans isolated from various specimens from 6 patients showed exactly the same;the invasive C.albicans infection was the most common in ICU,which was worthy of attention;the drug susceptibility testing results showed that the drug susceptibility rates of invasive Candida albicans to 5-fluorocytosine,amphotericin B,voriconazole,and posaconazole were all 100.00%,fluconazole 97.56%.CONCLUSION C.albicans infection remains the first place among invasive Candida infections,the genotyping indicates that invasive C.albicans is polymorphic,and the genotype of the invasive C.albicans are associated with that of the colonized isolates.