Department of Veterinary Medicine, School of Life and Sciences, Pontifícia Universidade Católica do Paraná, 1155 Imaculada Conceição Street, Curitiba, PR, 80215-901, Brazil.
Department of Medical Microbiology, Institute of Microbiology, Faculty of Biology, University of Warsaw, I. Miecznikowa 1, 02-096, Warsaw, Poland.
Acta Vet Scand. 2023 Feb 21;65(1):7. doi: 10.1186/s13028-022-00662-x.
Protothecosis is a rare infectious disease caused by unicellular, achlorophyllous, microalgae of the genus Prototheca, ubiquitously distributed in nature. The algae are emerging pathogens, whose incidence is increasing in both human and animal populations and serious systemic infections related to this pathogen have been increasingly described in humans in recent years. After mastitis in dairy cows, canine protothecosis is the second most prevalent form of the protothecal disease in animals. Here, we report the first case of chronic cutaneous protothecosis due to P. wickerhamii in a dog in Brazil, successfully treated with a long-term therapy with itraconazole in pulse.
Upon clinical examination, exudative nasolabial plaque, ulcered, and painful lesions in central and digital pads and lymphadenitis were observed in a 2-year-old mixed-breed dog, with a 4-month history of cutaneous lesions and contact with sewage water. Histopathological examination revealed intense inflammatory reaction, with numerous spherical to oval, encapsulated structures stained with Periodic Acid Schiff, compatible with Prototheca morphology. Tissue culture on Sabouraud agar revealed yeast-like, greyish-white colonies after 48 h of incubation. The isolate was subjected to mass spectrometry profiling and PCR-sequencing of the mitochondrial cytochrome b (CYTB) gene marker, leading to identification of the pathogen as P. wickerhamii. The dog was initially treated with oral itraconazole at a dosage of 10 mg/kg once daily. After six months, the lesions resolved completely, yet recurred shortly after cessation of therapy. The dog was then treated with terbinafine at a dose of 30 mg/kg, once daily for 3 months, with no success. The resolution of clinical signs, with no recurrence over a 36-months follow-up period, was achieved after 3 months of treatment with itraconazole (20 mg/kg) in pulse intermittently on two consecutive days a week.
This report highlights the refractoriness of skin infections by Prototheca wickerhamii with therapies proposed in the literature and suggests a new treatment option with oral itraconazole in pulse dosing for long-term disease control successfully performed in a dog with skin lesions.
原藻病是一种由单细胞、无叶绿素的微藻原藻属引起的罕见传染病，广泛分布于自然界中。这些藻类是新兴的病原体，其在人类和动物群体中的发病率正在增加，近年来，与这种病原体相关的严重系统性感染在人类中也越来越多地被描述。在奶牛乳腺炎之后，犬原藻病是动物中原藻病的第二大常见形式。在这里，我们报告了巴西首例由 P. wickerhamii 引起的慢性皮肤原藻病，该病例通过伊曲康唑脉冲治疗成功治愈。
在临床检查中，观察到一只 2 岁混血犬有渗出性鼻唇斑块、中央和指垫溃疡和疼痛病变以及淋巴结炎，该犬有 4 个月的皮肤病变病史，并接触过污水。组织病理学检查显示强烈的炎症反应，有许多球形到椭圆形的、被过碘酸希夫染色的、与原藻形态一致的包囊结构。萨布罗琼脂组织培养 48 小时后，显示出酵母样、灰白色的菌落。对分离株进行质谱分析和线粒体细胞色素 b（CYTB）基因标记的 PCR 测序，鉴定病原体为 P. wickerhamii。该犬最初以 10mg/kg 的剂量每天口服伊曲康唑进行治疗。六个月后，病变完全消退，但在停药后不久又复发。然后，该犬以 30mg/kg 的剂量每天口服特比萘芬治疗 3 个月，但没有成功。在伊曲康唑（20mg/kg）脉冲治疗 3 个月后，每周连续两天口服两次，临床症状完全缓解，36 个月随访期间无复发。
本报告强调了原藻属感染皮肤的难治性，以及文献中提出的治疗方法，并提出了一种新的治疗选择，即口服伊曲康唑脉冲治疗，用于控制长期疾病，该方法在一只皮肤病变的犬中成功实施。
