title: 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: Exophialais 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 ofExophialaspecies. 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 withinExophiala/RhinocladiellaThe remaining six isolates are shown by phylogenetic analyses based on four loci to represent two novelExophialaspecies. Four isolates from domestic bathrooms which form a sister species withExophiala lecanii-corniare described here asExophiala lavatrinasp. nov. The remaining two isolates, both from subcutaneous infections, are distantly related toExophiala oligospermaand are described here asExophiala campbelliisp. nov. The triazoles and terbinafine exhibited low MICs against allExophialaisolatesin vitroMALDI-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 ofE. lecanii-corniandE. lavatrina, 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 relevantExophialaspecies.
authors.affiliation: PHE UK National Mycology Reference Laboratory, Bristol, United Kingdom Andy.Borman@uhBristol.nhs.uk.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Borman
authors.affiliation: PHE UK National Mycology Reference Laboratory, Bristol, United Kingdom.
authors.forename: Mark
authors.initials: M
authors.lastname: Fraser
authors.affiliation: PHE UK National Mycology Reference Laboratory, Bristol, United Kingdom.
authors.forename: Adrien
authors.initials: A
authors.lastname: Szekely
authors.affiliation: School of Biological Sciences, University of Bristol, Bristol, United Kingdom.
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Larcombe
authors.affiliation: PHE UK National Mycology Reference Laboratory, Bristol, United Kingdom.
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Johnson
mesh_terms: D000818:Animals; D000935:Antifungal Agents / Q000494:pharmacology; D001393:Azoles / Q000494:pharmacology; D016000:Cluster Analysis; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000737:chemistry / Q000235:genetics; D004783:Environmental Microbiology; D005093:Exophiala / Q000737:chemistry / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D008826:Microbial Sensitivity Tests; D009181:Mycoses / Q000382:microbiology; D009281:Naphthalenes / Q000494:pharmacology; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D000077291:Terbinafine
chemical_list: D000935:Antifungal Agents; D001393:Azoles; D004271:DNA, Fungal; D021903:DNA, Ribosomal Spacer; D009281:Naphthalenes; D000077291:Terbinafine
keywords: DNA sequencing; Exophiala campbellii; Exophiala lavatrina; Exophiala species; MALDI-TOF; antifungal susceptibility; mass spectrometry; multigene phylogeny