Usefulness of Chromogenic Media in the Identification of Candida spp. Yeasts Compared to Mass Spectrometry.

Abstract

Yeasts of the Candida genus are part of the normal human microbiota but can cause infections (candidiasis) under certain conditions. While Candida albicans remains the most common etiological agent, the prevalence of non-albicans Candida species-such as C. glabrata, C. tropicalis, C. krusei, C. parapsilosis, C. kefyr, C. lusitaniae, and the emerging multidrug-resistant C. auris-has been increasing. Effective treatment of candidiasis requires rapid and accurate identification of the causative species, particularly due to species-specific antifungal agent resistance patterns. The aim of this study was to evaluate the usefulness of five chromogenic media for the differentiation of Candida species: BD CHROMagar Candida (Becton Dickinson), CHROM ID Candida (bioMérieux), CHROMAgar Candida Plus (CHROMAgar France, Biomaxima), CHROMAgar Candida Plus (GRASO Biotech), and Brilliance Candida Agar (OXOID). A total of 175 strains from the following species were tested: C. albicans, C. parapsilosis, C. dubliniensis, C. lusitaniae, C. tropicalis, C. glabrata, C. kefyr, C. krusei, and C. auris. Species identification was confirmed by MALDI-TOF mass spectrometry using the MALDI Biotyper system (Bruker). Colony morphology, especially color characteristics, was assessed on each medium. The morphological features of most Candida species were consistent with the manufacturer's descriptions and allowed for presumptive species-level identification. However, some species showed reproducible but previously undescribed morphological traits, including variations in colony shade. Notably, C. auris could not be reliably identified using BD, bioMérieux, or OXOID media. In conclusion, while chromogenic media are a helpful preliminary diagnostic tool, subtle differences in colony coloration can complicate interpretation. Diagnostic caution is recommended, and confirmatory methods such as MALDI-TOF remain essential for reliable identification, especially for emerging or less common Candida species.