Assessment of Bacterial and Fungal Contamination in Preservative-Free Multi-Dose Cyclosporine Eye Drops

Purpose: This study investigated the bacterial and fungal contamination of preservative-free, multidose cyclosporine (PFMD-Cyc) bottles. Methods: One hundred PFMD-Cyc eye drops administered by different patients for a minimum of 3 weeks were analyzed. The caps and first and second drops from the bottles underwent microbiological testing using sheep blood agar, chocolate agar, Sabouraud dextrose agar, and Brucella broth media. Conjunctival cultures were obtained from patients whose bottles were contaminated. The residual drug inside the contaminated bottles was examined by drilling the bottles' underside. Results: Microbial contamination was detected in 47% (n = 47) of the samples, with both poly- and monomicrobial growth. Fifty-nine species (25 gram-positive and 11 gram-negative bacteria, 15 yeasts, and 8 molds) were identified in the contaminated bottles. The most prevalent microorganisms were Staphylococcus epidermidis (n = 11), Candida parapsilosis (n = 7), and Fusarium spp. (n = 4). Conjunctival cultures from 4 patients revealed the same pathogens identified in the contaminated bottle, including Serratia marcescens, Klebsiella aerogenes, Staphylococcus aureus, and Candida parapsilosis. Conclusions: In addition to bacteria, a particularly high level of fungal contamination was detected. Conjunctival microorganisms were also detected in select samples. Patients should be advised to practice proper hand hygiene before administering eye drops. Moreover, meticulous attention to the storage conditions of medications during treatment is essential. Furthermore, research into fungal contamination of ophthalmical solutions, particularly immunosuppressive eye drops, is warranted.