国内首见真皮毛孢子菌引起皮肤感染一例

Cutaneous infection caused by Trichosporon dermatis： first case report in China

目的 报道1例真皮毛孢子菌引起的皮肤感染.方法 取皮损作直接镜检、真菌培养和组织病理学检查,分离菌株行DNA序列分析、API 20C AUX试剂盒检测、明胶液化试验、温度试验和体外药敏试验.结果 70岁男性患者,右内踝植物刺伤后出现肿块、溃疡9个月.皮损直接镜检阴性,组织病理显示真皮内菌丝和孢子.沙氏葡萄糖琼脂培养基培养出奶黄色酵母样菌落,微量培养可见假菌丝、真菌丝、关节孢子和芽生孢子,API 20C AUX试剂盒检测结果提示为土生念珠菌,DNA序列分析属于真皮毛孢子菌.菌株不能液化明胶,可在25～40 ℃环境下生长,对两性霉素B、伊曲康唑、伏立康唑、制霉菌素敏感.伊曲康唑治疗4个月后皮损完全愈合.结论 根据其形态学特点和DNA序列分析,菌株被鉴定为真皮毛孢子菌.伊曲康唑治疗有效.

Objective To report a case of cutaneous infection due to Trichosporon dermatis. Methods Lesional discharge and tissue were obtained and subjected to microscopic examination, fungal culture and histopathology, respectively. The fungal isolate was then identified with DNA sequence analysis, API 20C AUX system, gelatin liquefaction test, thermal tolerance test. Antifungal susceptibility test was also performed for the fungus. Results A 70-year-old male presented with a 9-month history of ulcerated swelling of the right medial malleolus after plant puncture. Direct microscopic examination of lesional discharge showed no fungal elements, but histopathological biopsy revealed hyphae and spores in the dermis. Yellowish white yeast-like colony grew on Sabouraud dextrose agar （SDA）. Slide culture showed pseudohyphae, true hyphae, arthroconidia and blastoconidia. The isolate was identified as Candida humicola by API 20C AUX system, but as T. dermatis by DNA sequence analysis. The strain was unable to liquefy gelatin, could grow at 25 ℃ to 40 ℃, and was sensitive to amphotericin B, itraconazole, voriconazole and nystatin. The skin lesion completely subsided after 4-month treatment with oral itraconazole. Conclusions The isolate is identified as T. dermatis according to morphological features and DNA sequence, which is sensitive to itraconazole.