Characterizing Candida Species with Distinctive “Feet”-forming Colony Morphology

Background: Candida infections are a major cause of morbidity and mortality worldwide, with non-albicans Candida (NAC) species becoming more prevalent.Conventional methods for Candida identification, such as microscopic morphology, germ tube tests, and growth on specific agars, have limitations.The distinctive "feet" appearance of Candida colonies has been proposed as a diagnostic feature for Candida albicans.The study aimed to characterize Candida species exhibiting distinctive feet-forming colony morphology. Materials and methods:In this observational study, 200 yeast isolates obtained from various clinical sources were initially identified using conventional phenotypic methods and subsequently confirmed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS).The presence of "feet" morphology was assessed on chocolate and blood agar after CO 2 incubation.Results: Among the 200 isolates, C. tropicalis was the most prevalent (40%), followed by C. albicans (25.5%).Colony extensions or "feet" were observed in 86.27% of C. albicans isolates on chocolate agar and 80.39% on blood agar.For C. tropicalis, "feet" were observed in 76.25% of isolates on chocolate agar and 72.5% on blood agar.No other Candida species showed this morphology. Conclusion:The "feet" morphology is not exclusive to C. albicans and should not be used as the sole criterion for its identification.When used alongside conventional tests, it can aid in accurately and rapidly diagnosing both C. albicans and NAC species, improving clinical outcomes.