In vitro natamycin susceptibility of ocular isolates of Fusarium and Aspergillus species: comparison of commercially formulated natamycin eye drops to pharmaceutical-grade powder.

The Clinical and Laboratory Standards Institute susceptibility method prohibits the use of pharmacy preparations, but obtaining pure powders is difficult. The activity of natamycin against isolates of Aspergillus and Fusarium species isolated from keratitis was assessed by using both powder and pharmacy eye drop preparations. Eye drop preparations may be a viable option for testing natamycin activity.