Comparison of E,E-Farnesol Secretion and the Clinical Characteristics of Candida albicans Bloodstream Isolates from Different Multilocus Sequence Typing Clades

Using multilocus sequence typing (MLST), Candida albicans can be subdivided into 18 different clades. Farnesol, a quorum-sensing molecule secreted by C. albicans, is thought to play an important role in the development of C. albicans biofilms and is also a virulence factor. This study evaluated whether C. albicans bloodstream infection (BSI) strains belonging to different MLST clades secrete different levels of E,E-farnesol (FOH) and whether they have different clinical characteristics. In total, 149 C. albicans BSI isolates from ten Korean hospitals belonging to clades 18 (n = 28), 4 (n = 23), 1 (n = 22), 12 (n = 17), and other clades (n = 59) were assessed. For each isolate, the FOH level in 24-hour biofilms was determined in filtered (0.45 μm) culture supernatant using high-performance liquid chromatography. Marked differences in FOH secretion from biofilms (0.10-6.99 μM) were observed among the 149 BSI isolates. Clade 18 isolates secreted significantly more FOH than did non-clade 18 isolates (mean ± SEM; 2.66 ± 0.22 vs. 1.69 ± 0.10 μM; P < 0.001). Patients with isolates belonging to clade 18 had a lower mean severity of illness than other patients, as measured using the "acute physiology and chronic health evaluation" (APACHE) III score (14.4 ± 1.1 vs. 18.0 ± 0.7; P < 0.05). This study provides evidence that C. albicans BSI isolates belonging to the most prevalent MLST clade (clade 18) in Korea are characterized by increased levels of FOH secretion and less severe illness.