Virulence of Clinical Candida Isolates

Abstract

The factors enabling Candida spp. infections are secretion of hydrolytic enzymes, adherence to surfaces, biofilm formation or morphological transition, and fitness attributes. The aim of this study was to investigate the correlation between known extracellular virulence factors and survival of Galleria mellonella larvae infected with clinical Candida. The 25 isolates were tested and the activity of proteinases among 24/24, phospholipases among 7/22, esterases among 14/23, hemolysins among 18/24, and biofilm formation ability among 18/25 isolates was confirmed. Pathogenicity investigation using G. mellonella larvae as host model demonstrated that C. albicans isolates and C. glabrata isolate were the most virulent and C. krusei isolates were avirulent. C. parapsilosis virulence was identified as varied, C. inconspicua were moderately virulent, and one C. palmioleophila isolate was of low virulence and the remaining isolates of this species were moderately virulent. According to our study, virulence of Candida isolates is related to the expression of proteases, hemolysins, and esterases.

Keywords: Candida virulence; Galleria mellonella; virulence factors.

Figure 1

Selected virulence factors of Candida spp.

Figure 2

Survival distribution function of G. mellonella infected with Candida isolates characterized by anidulafungin MIC values of ≤ 0.016 mg/L. The information on which number presented on figure represents what species—is described in Table 1.

Figure 3

Survival distribution of G. mellonella infected with Candida isolates characterized by anidulafungin MIC values between 0.031–0.25 mg/L. The information on which number presented on figure represents what species—is described in Table 1.

Figure 4

Survival distribution of G. mellonella infected with Candida isolates characterized by anidulafungin MIC values ≥ 0.5 mg/L. Information regarding number presented in the figure represents what species is described in Table 1.