Rapid Identification of Clinically Relevant Members of the Genus Exophiala by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry and Description of Two Novel Species, Exophiala campbellii and Exophiala lavatrina

Abstract

is a ubiquitous pleomorphic genus comprising at least 40 species, many of which have been associated with superficial, visceral, or systemic infections in humans, other mammals, or cold-blooded animals. In this study, we investigated the potential of matrix-assisted laser desorption-ionization time of flight mass spectrometry (MALDI-TOF MS) for the identification of species. A total of 89 isolates (including 50 human and 4 animal clinical isolates) stored in the National Collection of Pathogenic Fungi were identified by PCR amplification and sequencing of internal transcribed spacer region 1. Eighty-three of the isolates corresponded to 16 known species within The remaining six isolates are shown by phylogenetic analyses based on four loci to represent two novel species. Four isolates from domestic bathrooms which form a sister species with are described here as sp. nov. The remaining two isolates, both from subcutaneous infections, are distantly related to and are described here as sp. nov. The triazoles and terbinafine exhibited low MICs against all isolates MALDI-TOF MS successfully distinguished all 18 species and identified all isolates after appropriate reference spectra were created and added to commercial databases. Intraspecific mean log scores ranged from 1.786 to 2.584 and were consistently significantly higher than interspecific scores (1.193 to 1.624), with the exception of and , for which there was considerable log score overlap. In summary, MALDI-TOF MS allows the rapid and accurate identification of a wide range of clinically relevant species.

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

“…In the past few decades, several case reports have been published on invasive fungal infections caused by melanized fungi . However, extensive multicentric studies containing a large number of clinical isolates identified by MALDI was only published by Singh et al .…”

“…Multiple studies have reported an MALDI‐TOF MS‐based identification of bacteria, yeast, and hyaline fungi . However, only a few studies have reported a MALDI‐based identification of melanized fungi due to the lack of a standardized protein extraction protocol and a limited database availability . In addition, the present Bruker database contains very few entries of melanized fungi.…”

Rapid and Robust Identification of the Agents of Black-Grain Mycetoma by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

“…A variety of previous reports have highlighted the importance of supplementing the commercial databases supplied with the various MALDI-TOF platforms with appropriate reference MALDI-TOF spectra in order to improve identification success (29)(30)(31)(32). Since none of the 10 known species included in the test panel employed here were represented in the latest Bruker MSP database, appropriate reference spectra were generated and added to the commercial database.…”

“…Indeed, we recently demonstrated that MALDI-TOF MS could reliably discriminate between a wide variety of clinical and environmental Exophiala species (32). However, in all cases identification accuracy is limited by the availability of appropriate reference MALDI-TOF spectra in the commercial databases supplied with the various MALDI-TOF platforms (29)(30)(31)(32). Here we evaluated whether MALDI-TOF MS could be used to differentiate a variety of filamentous fungi implicated in black-grain eumycetoma and related subcutaneous clinical syndromes.…”

A Novel Exophiala Species Associated With Disseminated Granulomatous Inflammation in a Captive Eastern Hellbender (Cryptobranchus alleganiensis alleganiensis)

“…The ITS sequences of representative Exophiala species and relatives were obtained from GenBank based on BLASTn searches and on the datasets of Yong et al (12) and Borman et al (13). The sequences were assembled and aligned using MUSCLE (14) as implemented in Sequencher version 5.4.6-Build 46289 (Gene Codes Corp., MI USA) and refined visually using SE-AL (15).…”