Rapid and reliable identification of intact Candida clinical isolates using MALDI-TOF ICMS

Abstract

The significant increase in the frequency of candidiasis wide world has promoted the study and development of fast and reliable techniques aimed at the replacement of traditional methods used for identification and typing of Candida clinical isolates. Matrix Assisted Laser Desorption/Ionisation Time-Of-Flight lntact Cell Mass Spectrometry (MALDI-TOF ICMS) has been applied as current method for Candida identification in clinical laboratories. This method is reported as suitable fur routine identification in clinical laboratories and fast and reliable for identification of pathogenic yeasts. The main aim of this study was to compare MALDI-TOF ICMS performance with the classical phenotypic approach and molecular analyses to identify Candida species from clinical cases. Forty clinical Candida isolates preserved in URM Culture Collection fur I to 52 years were identified by morphological and biochemical analysis as Candida albicans (20), C. krusei (05), C. parapsilosis (11) and C. tropicalis (04). These identifications were compared with the discriminative capability of the new phenotypic approaches using MALDI-TOF ICMS. MALDI-TOF ICMS data demonstrated 15% discordance when compared with morphological and biochemical analyses. The discordant isolates were analysed by ITS sequencing which corroborated the MALDI-TOF ICMS identifications. Five Candida krusei isolates were renamed Issatchenkia orientalis by MALDI-TOF ICMS SARAMISTM database, which is their teleomorphic name. ln conclusion MALDI-TOF ICMS represents a rapid and reliable method of identifying Candida and also presents clear benefits when compared with the performance of existing daily routine methods applied at health centres and hospitals. Research leading to these results received funding from the European Community's Seventh Framework Program (FP7, 2007-2013), Research lnfrastructures Action, under grant agreement No. FP7-228310 (EMbaRC project). Thanks are also due to Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES, Brazil) for funding support.