This laboratory study evaluated the efficacy of amphotericin B against Fusarium solani and Aspergillus fumigatus in the corneal storage medium Optisol-GS.
Study design
Scientists prepared 10 vials of Optisol-GS and divided them into 4 groups: 2 positive controls (supplemented with amphotericin B and one each inoculated with F. solani or A. fumigatus), 2 negative controls (no amphotericin B or fungus), 3 supplemented with amphotericin B and inoculated with A. fumigatus and 3 supplemented with amphotericin B and inoculated with F. solani. A concentration of 0.255 μg/mL amphotericin B was used in all experiments.
Each vial was refrigerated at 4°C, and 1-ml samples were removed on days 2, 7 and 14. Samples were plated onto Sabouraud agar plates, incubated at 36°C for 48 hours, after which fungal colony counts were performed.
Outcomes
The average reduction in the growth of F. solani in the amphotericin B-supplemented vials was 44% on day 2, 79% on day 7, and 80% on day 14 when compared with the controls.
By contrast, the average reduction in the growth of A. fumigatus in the amphotericin B-supplemented vials was 40% on day 2 and 14% on day 7 when compared with the controls. Both amphotericin B-supplemented and control vials showed minimal fungal growth of A. fumigatus on day 14.
Limitations
This study was limited by its small sample size and laboratory environment that does not mimic the real-world warming and processing of tissue.
Clinical significance
While most prior reports have only examined the impact of amphotericin B supplementation against Candida, this study expands our knowledge of its use against other fungal organisms seen in post-keratoplasty patients such as Aspergillus and Fusarium. This data suggests that this concentration of amphotericin B is effective in reducing Aspergillus and Fusarium growth. Awareness of fungal infections in post-keratoplasty patients, particularly in the setting of endothelial keratoplasty, is of paramount concern to corneal surgeons.