每日一题_2023.07.06

A 38-year-old man presented with a 9-month history of a mildly itchy rash in his groin. The rash had been previously diagnosed as tinea cruris, but it had not improved with topical antifungal treatment. On physical examination, well-circumscribed, reddish-brown plaques were visualized in the inguinal folds when the patient elevated his genitals (left image). No scaling or satellite lesions were present. A potassium hydroxide preparation of skin scrapings was negative. Under a Wood’s lamp, the rash showed coral-red fluorescence (right image). What is the most likely causative organism?

38岁的男性患者出现了9个月的阴囊区轻度瘙痒的皮疹。该皮疹先前被诊断为股癣，但使用局部抗真菌治疗后并未见好转。在体格检查中，当患者抬起生殖器时，可以看到腹股沟皱襞处有界的红褐色斑块（左图）。没有出现脱屑或卫星损害。皮肤刮片的氢氧化钾制备检查结果为阴性。在伍德灯下，该皮疹显示珊瑚红色荧光（右图）。最可能的致病微生物是什么？

A. Candida albicans 白色念珠菌

B. Corynebacterium minutissimum 微小棒状杆菌

C. Malassezia furfur 糠秕马拉色菌

D. Pseudomonas aeruginosa 铜绿假单胞菌

E. Trichophyton mentagrophytes 须癣毛癣菌

答案解析：

在皮肤刮片的细菌培养中生长出微小棒状杆菌，并被诊断为腹股沟红斑。红斑是由微小隐球菌引起的一种浅表细菌性皮肤感染。典型表现在交错区或指间区。它可能被误认为是浅表的真菌皮肤感染，但它可以通过其红棕色和最小的鳞屑与皮肤癣菌病区别。由于细菌产生的卟啉引起特征性的珊瑚红色荧光，Wood的灯检查有助于诊断。

正确答案：B