Veterinary Diagnostic Laboratory, College of Veterinary Medicine, Michigan State University, Michigan, USA.
Faculty of Pharmacy, Federal University of Minas Gerais, Minas Gerais, Brazil.
J Med Microbiol. 2019 Apr;68(4):574-584. doi: 10.1099/jmm.0.000941. Epub 2019 Feb 8.
Pythiosis is an infection of humans and other animals caused by the fungal-like pathogen Pythium insidiosum. This pathogen causes life-threatening infection in the infected hosts. Culture, histopathology, serology and molecular tools are used to diagnose its infections. Successful management of pythiosis is directly linked to an early diagnosis. Thus, a rapid identification of putative cultures developing submerged sparsely septate hyphae is of extreme importance. However, few laboratories are familiar with the culture identification of this unique pathogen and its differential diagnosis with similar filamentous fungi.
We have evaluated the use of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF) on 53 isolates of P. insidiosum collected from cases of human and animal pythiosis in the USA and around the world. To assess the specificity of the approach, 18 pathogenic and saprotrophic filamentous fungal and fungal-like microbes were also tested.
MALDI-TOF in-house spectra correctly identified the 53 P. insidiosum isolates (score range 1.93-2.51). MALDI-TOF based identification within P. insidiosum isolates showed protein spectra variation between geographical diverse isolates. A mass spectrometry approach was able to discriminate P. insidiosum from the 18 filamentous fungal and fungal-like microbes in this study, including four Pythium spp. and Phytopythium litorale plant pathogenic species.
The data showed MALDI-TOF could be used for the accurate and rapid culture identification of P. insidiosum in the clinical laboratory.
Pythiosis 是一种由真菌样病原体 Pythium insidiosum 引起的人类和其他动物的感染。这种病原体在受感染的宿主中引起危及生命的感染。目前使用培养、组织病理学、血清学和分子工具来诊断其感染。成功管理 Pythiosis 直接与早期诊断相关。因此，快速识别可能出现的、生长稀疏有隔菌丝的潜在培养物至关重要。然而，很少有实验室熟悉这种独特病原体的培养鉴定及其与类似丝状真菌的差异诊断。
我们评估了基质辅助激光解吸电离飞行时间质谱（MALDI-TOF）在从美国和世界各地人类和动物 Pythiosis 病例中收集的 53 株 P. insidiosum 分离株中的应用。为了评估该方法的特异性，还测试了 18 种致病性和腐生性丝状真菌和真菌样微生物。
MALDI-TOF 内部谱正确识别了 53 株 P. insidiosum 分离株（评分范围 1.93-2.51）。MALDI-TOF 基于鉴定的 P. insidiosum 分离株显示出地理多样性分离株之间蛋白质谱的变化。该质谱方法能够将 P. insidiosum 与本研究中的 18 种丝状真菌和真菌样微生物区分开来，包括 4 种 Pythium spp. 和 Phytopythium litorale 植物病原种。
数据表明 MALDI-TOF 可用于临床实验室中 P. insidiosum 的准确、快速培养鉴定。
