MALDI-TOF MS-Based Identification of Melanized Fungi is Faster and Reliable After the Expansion of In-House Database.

Abstract

Invasive fungal infections caused by melanized fungi are a growing concern. Rapid and reliable identification plays an important role in optimizing therapy. Matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS)-based identification has emerged as a faster and more accurate diagnostic technique. However, lack of a protein extraction protocol and limited database restricts the identification of melanized fungi by MALDI-TOF MS. The study is designed to standardize protein extraction protocol, to enrich the existing, and to create an in-house database for the rapid identification of melanized fungi. In this study, 59 sequence-confirmed, melanized fungi were used to expand and to create an in-house database using a modified protein extraction protocol. A total of 117 clinical isolates are further used to validate the created database. Using existing Bruker database, only 29(24.8%) out of 117 moulds could be identified. However, all the isolates are identified accurately by supplementing the Bruker database with the created in-house database. MALDI-TOF MS takes significantly lesser time for identification compared to DNA sequencing. An expanded database with modified protein extraction protocol can reduce significant time to identify melanized fungi by MALDI-TOF MS.