Enzymatic characterization of clinical and environmental Cryptococcus neoformans strains isolated in Italy

Cryptococcus neoformans is an encapsulated yeast causing mainly opportunistic infections.The virulence factors involved in cryptococcosis pathogenesis include the presence and the size of thepolysaccharide capsule, the production of melanin by phenoloxidase, the growth at 37◦C and the enzymesecretion like proteinase, phospholipase and urease. Many other enzymes are secreted by C. neoformansbut their role in the fungus virulence is not yet known. In order to investigate this topic, we compared the phospholipase production between 205 strains from patients and 32 from bird droppings, and we examined its relationship to phenoloxidase production. We further characterized the strains by determining the activity of 19 different extracellular enzymes. The higher phospholipase production in the clinical isolates group confirms the possible role of this enzyme in the cryptococcosis pathogenesis. The extracellular activities of the enzymes acidphosphatase, alfa-glucosidase and leucine arylamidase, tested by means of the API ZYM commercial kit,suggest their possible role as virulence factors in Cryptococcus infections.