[Identification of Candida yeasts: Conventional methods and MALDI-TOF MS]

Abstract

Background: Invasive fungal infections are increasing, and Candida yeasts are the main cause. Species other than Candida albicans are becoming more frequent, and some of them may have variable patterns of susceptibility to antifungal agents, making it important to identify them correctly. Conventional identification methods used by most laboratories may present with drawbacks. Mass spectrometry (MALDI-TOF MS) has emerged as an alternative method.

Aims: The aim of this study was to evaluate the concordance of the identification, at species level, by conventional methods (API) and MALDI-TOF MS.

Methods: The following species and number of isolates were studied: Candida parapsilosis (28), Candida glabrata (34), Candida krusei (24), Candida tropicalis (45), Candida guilliermondii (30), C. albicans (28), Candida dubliniensis (6), Candida kefyr (1), and Candida lipolytica (1) from the strain collection of Autonomous City of Buenos Aires Mycology Network (RMCABA). The strains C. parapsilosis 22019, C. glabrata 90030, C. krusei 6258 and C. albicans 68548 from the American Type Culture Collection (ATCC) were also included. Discrepancies were resolved by genotyping.

Results and conclusions: The direct concordance between the conventional identification method and MALDI-TOF MS was 92.5% (186/201).

Keywords: Candida spp.; Identificación de levaduras; MALDI-TOF MS; Yeast identification.