This study demonstrated that caspofungin used at MIC was not sufficient to reduce C. albicans biofilms, but it suggested an activity on C. parapsilosis biofilms depending on their maturation age. This study also indicated that caspofungin used at 2 mg/L could be a good candidate in the prevention of candidiasis associated with silicone medical devices. Our results also suggested that fluconazole resistance of yeasts did not affect caspofungin activity.

This study demonstrated the anti-adherent activity of caspofungin but indicated a reduced effect in the case of in vitro fluconazole resistance. These results indicated a possible relationship between the efficiency of caspofungin to inhibit the first step of the development of C. albicans biofilm and the resistance of C. albicans to fluconazole in vitro.

A 95 kDa metallopeptidase of Candida albicans could be involved in the process of dissemination of the yeast. Matrix metalloproteases (MMPs) are also responsible for collagen breakdown in inflammatory and malignant processes. We tested six compounds on the C. albicans enzyme. Doxycycline, gentamicin, cefalothin, galardin, and elaidic and oleic acids are known for their capacity to inhibit some MMPs. Amongst these agents, only oleic acid was able to markedly inhibit the purified metallopeptidase at very low concentrations. Moreover, this fatty acid inhibited the secretion of the enzyme in the culture medium without altering the yeast viability.

Among potential virulence factors of Candida albicans, enzymes seem to play an important role. Many studies concern the secreted aspartic proteinases (saps), and the degradation of some components of the subendothelial extracellular matrix by the isoenzyme sap2 has been proved. Nevertheless, other proteolytic enzymes could be involved in the pathogenicity of the yeast. We studied the degradation of four constitutive proteins of the extracellular matrix: type I and IV collagens, laminin and fibronectin, by a 95-kDa metallopeptidase, localised in the cell wall of C. albicans. Each of these constituents was incubated with the purified enzyme and its degradation products analysed by an electrophoretic method. We observed that type I collagen and fibronectin were totally degraded by the enzyme whereas type IV collagen and laminin were only partially degraded. The C. albicans metallopeptidase may play a role in the degradation of the subendothelial extracellular matrix components. This enzyme could facilitate the migration of the yeast in the tissues after crossing the endothelial layer, allowing the fungal invasion of target organs.

This study investigates the influence of treatment of plastic and extracellular matrix (ECM) proteins with chlorhexidine or benzalkonium chloride on subsequent adherence of Candida albicans. Three concentrations were tested for each antiseptic: (i) chlorhexidine, MIC (6.25-12.5 mg/L), 80 x MIC and 800 x MIC; and (ii) benzalkonium chloride, MIC (3.12 mg/L), 40 x MIC and 1600 x MIC. Chlorhexidine and benzalkonium chloride activities were correlated with the tested concentrations. Antiseptics used at MIC were unable to modify the adherence to plastic or ECM proteins. Chlorhexidine (80 x MIC) induced a decrease in plastic adherence of 31% of the 15 strains used and an increase in ECM protein adherence of 13% of strains. Benzalkonium chloride (40 x MIC) induced a decrease in adherence to ECM proteins or plastic of 13-27% of strains. Our results indicated that the treatment with 1600 x MIC benzalkonium chloride could induce the opposite effect on adherence, depending on the surface: 60% of the strains showed an increase in their adherence to ECM proteins, whereas 93% of the strains showed a decrease in their adherence to plastic. A similar phenomenon was observed after treatment with 800 x MIC chlorhexidine: 60% of the strains showed an increase in their adherence to ECM proteins, whereas 67% showed a decrease in adherence to plastic. Treatment of medical devices with at least 5000 mg/L of chlorhexidine or benzalkonium chloride could therefore reduce C. albicans adherence to plastic surfaces, but would be unable to prevent fungal adherence to ECM proteins.