念珠菌与黑色素的相关性研究

Relationship between Candidas and melanin

目的念珠菌在深部真菌感染中占第2位。文中观察临床分离念珠菌的产黑素情况。方法收集临床分离的念珠菌菌株360株,用3种产黑素培养基(咖啡酸玉米吐温、多巴和基本培养基)于35℃培养,观察培养基变色情况,并以新生隐球菌作阳性对照,通过透射电子显微镜及电子自旋共振波谱仪进一步观察。结果新生隐球菌在3种产黑培养基上均显色,第5天时,白念珠菌标准株SC5314开始变为棕褐色。360株临床念珠菌第10天时,12株在多巴培养基上变为棕褐色,15株在基本培养基上变棕褐色。透射电镜下隐球菌可看到在细胞壁的外层有一高电子密度层,白念珠菌SC5314和产色素的临床念珠菌细胞壁外层无电子致密层;白念珠菌产黑最明显,波谱仪下未检测到信号。结论仅凭产色培养基观察念珠菌是否产黑色素可靠度尚有欠缺,需结合透射电镜和电子自旋共振波谱仪进一步验证。

Objective Candidas rank as the second factor of deep fungal infection .This study aimed to investigate the rela-tionship between Candidas and melanin by screening clinically isolated melanin -producing Candidas . Methods We incubated 360 strains of clinically isolated Candidas with caffeic acid , DOPA agar , and minimal medium at a temperature of 35℃, with Cryptococcus neoformans as the positive control .We observed the changes in the culture media using transmission electron microscopy （TEM） and electron spin resonance （ ESR） spectroscopy . Results Cryptococcus neoforman produced pigmentation in all the three types of medi -um.At 5 days, a standard strain of Candida albicans SC 5314 turned dark brown in the DOPA agar and minimal medium and , at 10 days, 12 and 15 of the 360 Candida strains turned dark brown in the DOPA agar and minimal medium , respectively, which were not shown to be melanin by TEM and ESR spectroscopy . Conclusion Culture media are not reliable enough for the identification of mel-anin-producing Candidas , and the observations need to be further verified by TEM and ESR spectroscopy .