Enhanced detection of Pythium insidiosum via lipid profiling with matrix-assisted laser desorption ionization time of flight mass spectrometry

Abstract

Pythiosis is a severe disease in humans and animals globally, caused by the pathogenic oomycete Pythium insidiosum. Early and accurate detection is crucial for effective treatment, but traditional diagnostic methods have limitations. This study presents an alternative approach using Matrix-Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS) for lipid profiling to efficiently identify P. insidiosum. The study involved extracting microbial lipid components using optimized chloroform: methanol biphasic method and creating a lipid profile database with samples from 30 P. insidiosum isolates and 50 various fungi. The methodology was validated on 25 blinded samples for assay detection performance. Unique lipid profiles allowed species-specific identification with high efficiency: scores ≥ 2.682 indicated P. insidiosum, scores ≤ 2.512 suggested fungi, and scores in between pointed to other oomycetes. The assay demonstrated sensitivity, specificity, and accuracy of 100%, 80%, and 88%, respectively, for detecting P. insidiosum. The limited detection specificity was due to false positive samples from closely related Pythium species, which are not a significant clinical concern. The findings show that MALDI-TOF MS lipid profiling can efficiently identify P. insidiosum, offering significant advantages in sample preparation, stability, and reproducibility over protein profile-based methods. This study marks the first instance of lipid profiles being reported for P. insidiosum, paving the way for clinical use in improving accurate detection and facilitating timely treatment interventions.