Kidd Sarah E, Sandoval-Denis Marcelo, Malik Richard, Hagen Ferry, Rodrigues Anderson M
National Mycology Reference Centre, Microbiology and Infectious Diseases, SA Pathology, Adelaide, SA 5000, Australia.
School of Biological Sciences, University of Adelaide, Adelaide, SA 5000, Australia.
Med Mycol. 2025 Apr 2;63(4). doi: 10.1093/mmy/myaf034.
Sporothrix species (Ascomycota, Ophiostomatales) are dimorphic fungi with diverse ecological niches, ranging from mammalian, plant, and insect pathogens to fungicolous organisms. Here, we describe Sporothrix davidellisii (CBS 147636T), a novel pathogenic species within the S. pallida complex isolated from a case of feline sporotrichosis in Melbourne, Australia. Phylogenetic analyses based on ITS, β-tubulin (BT2), calmodulin (CAL), and translation elongation factor 1-α (EF1-α) sequences confirmed its distinctiveness, with ITS sequence identity to its closest relative (S. chilensis) not exceeding 97.6%. The assembled genome is 39.02 Mb (eight contigs) with a 27.2 kb mitochondrial genome and a total of 12,631 predicted genes. Genetic diversity analyses revealed moderate nucleotide variation in the ITS region (π = 0.055), greater diversity in BT2 (π = 0.098), and CAL (π = 0.118), supporting its status as a unique species. Morphological studies revealed distinctive characteristics differentiating S. davidellisii from its nearest relatives, including elongated clavate sympodial conidia and sessile conidia. Notably, S. davidellisii exhibits yeast-like growth at 37°C, forming ellipsoid to ovoid budding cells in liquid media, although cigar-shaped yeasts, characteristic of highly virulent Sporothrix species, are rarely observed. This ability to transition to a yeast-like form, combined with its high-temperature tolerance (growth up to 40°C), underscores its opportunistic pathogenic potential. The pathogenic role of S. davidellisii highlights the importance of monitoring atypical Sporothrix infections in feline hosts, which may serve as environmental sentinels for emerging fungal pathogens. These findings expand the taxonomy of Sporothrix, contributing to our understanding of the evolutionary complexity and zoonotic potential of species within the S. pallida complex.
孢子丝菌属（子囊菌门，长喙壳目）是具有多种生态位的双态真菌，从哺乳动物、植物和昆虫病原体到真菌寄生生物。在此，我们描述了大卫孢子丝菌（CBS 147636T），这是从澳大利亚墨尔本一例猫孢子丝菌病病例中分离出的苍白孢子丝菌复合体中的一个新的致病物种。基于内转录间隔区（ITS）、β-微管蛋白（BT2）、钙调蛋白（CAL）和翻译延伸因子1-α（EF1-α）序列的系统发育分析证实了其独特性，其与最亲近的亲属（智利孢子丝菌）的ITS序列同一性不超过97.6%。组装的基因组为39.02 Mb（8个重叠群），线粒体基因组为27.2 kb，共预测有12,631个基因。遗传多样性分析显示，ITS区域的核苷酸变异适中（π = 0.055），BT2（π = 0.098）和CAL（π = 0.118）的多样性更大，支持了其作为独特物种的地位。形态学研究揭示了大卫孢子丝菌与其最亲近亲属的不同特征，包括细长棒状的合轴分生孢子和无柄分生孢子。值得注意的是，大卫孢子丝菌在37°C时呈现酵母样生长，在液体培养基中形成椭圆形至卵形的芽殖细胞，尽管很少观察到高毒力孢子丝菌物种特有的雪茄形酵母。这种转变为酵母样形态的能力，加上其高温耐受性（生长温度可达40°C），突出了其机会性致病潜力。大卫孢子丝菌的致病作用凸显了监测猫宿主中非典型孢子丝菌感染的重要性，猫宿主可能作为新出现真菌病原体的环境哨兵。这些发现扩展了孢子丝菌的分类学，有助于我们理解苍白孢子丝菌复合体中物种的进化复杂性和人畜共患病潜力。
