Phenotypical Differences at the Physiological and Clinical Level between Two Genetically Closely Related Clavispora lusitaniae Strains Isolated from Patients.

The occurrence of non-albicans species within the genus Candida poses a major challenge in the clinical setting. Clavispora lusitaniae, formerly known as Candida lusitaniae, has gained attention due to its potential multidrug resistance, particularly to amphotericin B (AmB). While intrinsic resistance to AmB is rare, secondary resistance may develop during treatment due to phenotypic rearrangement and the reorganization of the cell wall. Although there is evidence of genetic variability within C. lusitaniae, comprehensive genomic studies are lacking. This study examines the physiological differences within Candida species and focuses on the medical implications of this. Using two case reports, significant physiological and resistance differences between two strains of C. lusitaniae are demonstrated, highlighting the need for further research into genetic variability. While one strain showed higher resistance to antifungal drugs and slower growth compared to Strain 2, both strains showed minimal beta-D-glucan production, suggesting alternative pathogenic mechanisms. The study underlines the importance of understanding microbial adaptation and selection mechanisms, especially in the clinical setting, to effectively combat emerging drug resistance. Furthermore, research is needed to clarify the complex interplay between environmental causes, physiological traits, and the mechanisms of drug resistance in C. lusitaniae.