Antimycotic efficacy and safety of a new cold corneal storage medium by time–kill and toxicity studies

Purpose: To evaluate a new corneal cold storage medium including an antimycotic tablet (Kerasave, AL.CHI.MI.A. S.r.l.).

Methods: Kerasave and tryptone soy broth (control) were inoculated with 10 and 10 colony-forming units (CFU)/mL of 6 Candida isolates (Candida albicans [n = 4], Candida tropicalis [n = 1], and Candida glabrata [n = 1]). Minimum inhibitory concentrations (MICs) were determined using amphotericin B Etest strips. Sterile porcine corneas contaminated with 10 CFU/mL of each isolate were incubated in Kerasave and control at 4°C. Growth rate and Log10 reduction at 4°C at different time intervals were determined for liquid samples and tissue homogenates. Kerasave biocompatibility was assessed according to ISO 10993-5 and ISO 10993-10.

Results: No C. albicans or C. tropicalis colonies were recovered from Kerasave inoculated with 10 CFU/mL after incubation for 3 days at 4°C. C. glabrata was inhibited but not killed after 3 days at 4°C. Four of the 6 strains contaminated with 10 CFU/mL demonstrated a significant ≥ 3 Log10 reduction in media and tissue homogenates within 5 days as compared to controls (p < 0.01). Amphotericin B MICs ranged from 0.19 to 0.38 μg/mL for C. albicans (n = 3) and C. tropicalis (n = 1). C. glabrata showed reduced susceptibility (0.5 μg/mL) and 1 C. albicans was resistant to amphotericin B (≥ 1 μg/mL). Kerasave was not cytotoxic, irritating, or sensitizing according to the ISO standards.

Conclusions: Kerasave showed high antifungal efficacy against susceptible fungal strains at 4°C in the presence and absence of corneal tissue. Resistant strains to amphotericin B were not eliminated by Kerasave. Kerasave is not cytotoxic, irritating, or sensitizing.