In Vitro Determination of Hydrolytic Enzymes and Echinocandin Susceptibility in Mexican Clinical Isolates of Candida glabrata Sensu Stricto

Abstract

Background: Candida glabrata is an opportunistic yeast that has emerged as a cause of human fungal disease, and is a complex of three closely related species. Until now, there is not enough information about its virulence attributes. Moreover, its resistance to echinocandins has been documented, which is a cause of clinical concern. Objectives: The objective of this study was to evaluate the in vitro production of aspartyl proteinase, phospholipase, esterase, hemolysin, DNase, and coagulase in a subset of 107 Mexican clinical isolates of C. glabrata sensu stricto, as well as to determinate its echinocandin susceptibility. Methods: The enzymatic determinations were carried out in plate assays using specific substrates, excepting coagulase, which was determined by the classic tube test. Antifungal susceptibility testing was determined in accordance with the CLSI broth microdilution method. Results: Aspartyl proteinase, hemolysin, and phospholipase were detected in 100%, 95%, and 79% of isolates, respectively. Blood isolates were associated with a very strong activity of aspartyl proteinase and hemolysin, and those recovered from vaginal swabs were associated with very strong production of aspartyl proteinase, phospholipase, and hemolysin. All isolates were susceptible to echinocandins, except one bloodstream isolate, which was resistant to echinocandins. Conclusions: A very strong activity of aspartyl proteinase and hemolysin was particularly associated with both, bloodstream, and vaginal swab isolates. Echinocandin resistance was rare.