Rapid and reliable MALDI-TOF mass spectrometry identification of Candida non-albicans isolates from bloodstream infections

Abstract

Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) fingerprinting has recently become an effective instrument for rapid microbiological diagnostics and in particular for identification of micro-organisms directly in a positive blood culture. The aim of the study was to evaluate a collection of 82 stored yeast isolates from bloodstream infection, by MALDI-TOF MS; 21 isolates were identified also directly from positive blood cultures and in the presence of other co-infecting micro-organisms. Of the 82 isolates grown on plates, 64 (76%) were correctly identified by the Vitek II system and 82 (100%) by MALDI-TOF MS; when the two methods gave different results, the isolate was identified by PCR. MALDI-TOF MS was unreliable in identifying two isolates (Candida glabrata and Candida parapsilosis) directly from blood culture; however, direct analysis from positive blood culture samples was fast and effective for the identification of yeast, which is of great importance for early and adequate treatment.

Cambios clínicos y epidemiológicos de candidemias en pacientes adultos desde 2000 a 2013

“…Este nuevo recurso permite la correcta identificación de especie superando a Vitek II 17 , y aún es posible esperar mayores beneficios si se usa directamente la sangre de la botella del frasco de hemocultivo logrando identificación en 30 min; con ello se alcanza una concordancia con los métodos tradicionales de 96% para C. albicans y 86% para C. no-albicans 17,18 .…”

Advantages of Using Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry as a Rapid Diagnostic Tool for Identification of Yeasts and Mycobacteria in the Clinical Microbiological Laboratory

“…The use of matrixassisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for the rapid identification of clinical yeast and mycobacterial isolates has been evaluated in some studies (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25). However, there has been a limited number of direct comparison studies focusing on the performance of the two MALDI-TOF systems to rapidly identify yeast and mycobacterial clinical isolates (26)(27)(28).…”

Direct identification of yeasts from blood culture by MALDI-TOF mass spectrometry

“…In their study, Lavergne (2013) and Marinach-Patrice (2010) used the same protocol as ours and were able to rapidly and precisely identify the main Candida species, thus avoiding the need for culture on a specific medium. In a second study carried out by Pulcrano et al (2013), on Candida non-albicans with 0.5% SDS, all 82 strains were identified at the species level with a score greater than 2.…”

“…In our series, only one genus of yeast, Candida, was isolated unlike Yan et al (2011), who found yeasts belonging to two genera: Candida and Cryptococcus. Pulcrano et al (2013) identified yeasts of the genera Saccharomyces and Lodderomyces in addition to the genus Candida.…”

“…Ferroni et al (2010) identified 10 species of C. albicans out of 20 Candida spp. Numerous other species of non-Candida yeasts and Candida nonalbicans were also identified by Pulcrano et al (2013), these being 53 species of C. parapsilosis, 11 species of C. glabrata, 8 species of C. tropicalis, 6 species of Candida guillermondii, 1 species of Lodderomyces elongipsorus and 1 species of Saccharomyces cerevisiae. C. albicans is the species most frequently responsible for invasive candidiasis, although according to Bille et al (2012), other non-albicans species, including C. tropicalis, C. parapsilosis, C. glabrata and C. krusei, are becoming increasingly common.…”