Yücesoy Mine, Marol Serhat
Dokuz Eylül University, Faculty of Medicine, Department of Microbiology and Clinical Microbiology, Izmir, Turkey.
Ann Clin Microbiol Antimicrob. 2003 Oct 29;2:8. doi: 10.1186/1476-0711-2-8.
The importance of identifying the pathogenic fungi rapidly has encouraged the development of differential media for the presumptive identification of yeasts. In this study two differential media, CHROMagar Candida and bismuth sulphite glucose glycine yeast agar, were evaluated for the presumptive identification of yeast species.
A total number of 270 yeast strains including 169 Candida albicans, 33 C. tropicalis, 24 C. glabrata, 18 C. parapsilosis, 12 C. krusei, 5 Trichosporon spp., 4 C. kefyr, 2 C. lusitaniae, 1 Saccharomyces cerevisiae and 1 Geotrichum candidum were included. The strains were first identified by germ tube test, morphological characteristics on cornmeal tween 80 agar and Vitek 32 and API 20 C AUX systems. In parallel, they were also streaked onto CHROMagar Candida and bismuth sulphite glucose glycine yeast agar plates. The results were read according to the color, morphology of the colonies and the existance of halo around them after 48 hours of incubation at 37 degrees C.
The sensitivity and specificity values for C. albicans strains were found to be 99.4, 100% for CHROMagar Candida and 87.0, 75.2% for BiGGY agar, respectively. The sensitivity of CHROMagar Candida to identify C. tropicalis, C. glabrata and C. krusei ranged between 90.9 and 100% while the specificity was 100%. The sensitivity rates for BiGGY agar were 66.6 and 100% while the specificity values were found to be 95.4 and 100% for C. tropicalis and C. krusei, respectively.
It can be concluded that the use of CHROMagar Candida is an easy and reliable method for the presumptive identification of most commonly isolated Candida species especially C. albicans, C. tropicalis and C. krusei. The lower sensitivity and specificity of BiGGY agar to identify commonly isolated Candida species potentially limits the clinical usefulness of this agar.
快速鉴定致病真菌的重要性推动了用于酵母初步鉴定的鉴别培养基的发展。在本研究中，对两种鉴别培养基——科玛嘉念珠菌显色培养基（CHROMagar Candida）和亚硫酸铋葡萄糖甘氨酸酵母琼脂（bismuth sulphite glucose glycine yeast agar，BiGGY琼脂）进行了评估，以用于酵母菌种的初步鉴定。
共纳入270株酵母菌株，包括169株白色念珠菌、33株热带念珠菌、24株光滑念珠菌、18株近平滑念珠菌、12株克柔念珠菌、5株丝孢酵母属菌种、4株解脂念珠菌、2株葡萄牙念珠菌、1株酿酒酵母和1株白地霉。首先通过芽管试验、玉米粉吐温80琼脂上的形态学特征以及Vitek 32和API 20 C AUX系统对这些菌株进行鉴定。同时，将它们划线接种于科玛嘉念珠菌显色培养基平板和亚硫酸铋葡萄糖甘氨酸酵母琼脂平板上。在37℃孵育48小时后，根据菌落的颜色、形态以及菌落周围晕圈的存在情况读取结果。
发现科玛嘉念珠菌显色培养基对白色念珠菌菌株的敏感性和特异性值分别为99.4%、100%，而BiGGY琼脂的敏感性和特异性值分别为87.0%、75.2%。科玛嘉念珠菌显色培养基鉴定热带念珠菌、光滑念珠菌和克柔念珠菌的敏感性在90.9%至100%之间，而特异性为100%。BiGGY琼脂对热带念珠菌和克柔念珠菌的敏感性率分别为66.6%和100%，而特异性值分别为95.4%和100%。
可以得出结论，使用科玛嘉念珠菌显色培养基是一种简单可靠的方法，可用于初步鉴定最常见分离出的念珠菌菌种，尤其是白色念珠菌、热带念珠菌和克柔念珠菌。BiGGY琼脂鉴定常见分离出的念珠菌菌种时较低的敏感性和特异性可能限制了该琼脂在临床上的实用性。
