Killing kinetics of anidulafungin,caspofungin and micafungin against Candida parapsilosis species complex: Evaluation of the fungicidal activity

Background

Candida parapsilosis, Candida metapsilosis and Candida orthopsilosis are emerging as relevant causes of candidemia. Moreover, they show differences in their antifungal susceptibility and virulence. The echinocandins are different in terms of in vitro antifungal activity against Candida. Time-kill (TK) curves represent an excellent approach to evaluate the fungicidal activity of antifungal drugs.

Aims

To compare the fungicidal activities of anidulafungin, caspofungin and micafungin against C. parapsilosis species complex by TK curves.

Methods

Antifungal activities of three echinocandins against C. parapsilosis, C. metapsilosis and C. orthopsilosis were studied by TK curves. Drug concentrations assayed were 0.25, 2 and 8 μg/ml. CFU/ml were determined at 0, 2, 4, 6, 24 and 48 h.

Results

Killing activities of echinocandins were species-, isolates- and concentration-dependent. Anidulafungin reached the fungicidad endpoint for 6 out of 7 isolates (86%); it required between 13.34 and 29.67 h to reach this endpoint for the three species studied, but more than 48 h were needed against one isolate of C. orthopsilosis (8 μg/ml). Caspofungin fungicidal endpoint was only achieved with 8 μg/ml against one isolate of C. metapsilosis after 30.12 h (1 out of 7 isolates; 14%). Micafungin fungicidal endpoint was reached in 12.74–28.38 h (8 μg/ml) against one isolate each of C. parapsilosis and C. orthopsilosis, and against both C. metapsilosis isolates (4 out of 7 isolates; 57%).

Conclusions

C. metapsilosis was the most susceptible species to echinocandins, followed by C. orthopsilosis and C. parapsilosis. Anidulafungin was the most active echinocandin against C. parapsilosis complex.