Abstract：
Dimorphism is known among the etiologic agents of endemic mycoses as well as in filamentous Mucorales. Under appropriate thermal conditions, mononuclear yeast forms alternate with multi-nucleate hyphae. Here, we describe a dimorphic mucoralean fungus obtained from the sputum of a patient with Burkitt lymphoma and ongoing graft-versus-host reactions. The fungus is described as Mucor germinans sp. nov. Laboratory studies were performed to simulate temperature-dependent dimorphism, with two environmental strains Mucor circinelloides and Mucor kunryangriensis as controls. Both strains could be induced to form multinucleate arthrospores and subsequent yeast-like cells in vitro. Multilateral yeast cells emerge in all three Mucor species at elevated temperatures. This morphological transformation appears to occur at body temperature since the yeast-like cells were observed in the lungs of our immunocompromised patient. The microscopic appearance of the yeast-like cells in the clinical samples is easily confused with that of Paracoccidioides. The ecological role of yeast forms in Mucorales is discussed.IMPORTANCEMucormycosis is a devastating disease with high morbidity and mortality in susceptible patients. Accurate diagnosis is required for timely clinical management since antifungal susceptibility differs between species. Irregular hyphal elements are usually taken as the hallmark of mucormycosis, but here, we show that some species may also produce yeast-like cells, potentially being mistaken for Candida or Paracoccidioides. We demonstrate that the dimorphic transition is common in Mucor species and can be driven by many factors. The multi-nucleate yeast-like cells provide an effective parameter to distinguish mucoralean infections from similar yeast-like species in clinical samples.
摘要：
在地方性真菌病和丝状Mucorales的病因学中，已知双态性。在适当的热条件下，单核酵母与多核菌丝交替形成。这里,我们描述了从Burkitt淋巴瘤和持续移植物抗宿主反应患者的痰中获得的二态粘液真菌。该真菌被描述为毛霉。11月。进行了实验室研究以模拟温度依赖性双态，以两个环境菌株为对照。两种菌株都可以在体外诱导形成多核的关节孢子和随后的酵母样细胞。在升高的温度下，所有三种Mucor物种中都出现了多边酵母细胞。由于在我们的免疫受损患者的肺中观察到酵母样细胞，因此这种形态转化似乎发生在体温下。临床样品中酵母样细胞的微观外观很容易与副球菌的外观相混淆。讨论了酵母形式在Mucorales中的生态作用。重要头孢霉菌病是一种在易感患者中具有高发病率和死亡率的破坏性疾病。由于不同物种之间的抗真菌药物敏感性不同，因此需要准确的诊断才能及时进行临床治疗。不规则菌丝元素通常被视为毛霉菌病的标志，但在这里,我们发现一些物种也可能产生酵母样细胞，可能被误认为念珠菌或副球菌。我们证明了二态转变在Mucor物种中很常见，并且可以由许多因素驱动。多核酵母样细胞提供了有效的参数来区分临床样品中的粘液菌感染与相似的酵母样物种。
