An environmental control experiment for contamination of the production and storage of 20% autologous serum eye drops.

Purpose: To investigate the sterility of autologous serum eye drops used for ocular surface diseases. Methods: A total of 100 patients were enrolled. The serum was prepared as follows: 20% serum (20% S), 20% serum with dexamethasone (0.02 mg/ml) (20% S + Dex), and 20% serum with levofloxacin (0.1 mg/ml) (20% S + Lev). Serum samples were collected for normal microbial cultivation at 1, 3, 5, 7, 10, 14, 21, and 28 days. The last samples were also assessed on the 28th day by airtight microbial cultivation. Results: A total of 2400 samples were cultured, and the bacterial contamination rates of 20% S, 20% S+ Dex, and 20% S + Lev group were 4.75%, 3.38%, and 0.88%, respectively, for normal microbial cultivation. There was no significant difference in bacterial contamination among the three groups with times (P = .502). Bacterial contamination of the 20% S + Lev group showed a significant difference in comparison with the 20% S or 20% S + Dex group (P < .05) in two culture methods; however, no significant difference was found between the 20% S and 20% S + Dex group (P = .208). There were two samples positive for fungi in the 20% S and 20% S + Dex group and three samples in the 20% S + Lev group in normal cultivation during 28 days. None of the samples was positive with fungi in airtight cultivation on the 28th day. There was also less bacterial contamination in airtight cultivation than in normal cultivation for the three groups on the 28th day. Conclusions: Our study shows that 20% autologous serum drops can be safely prepared and stored at 4 degrees C in an open system under a strict protocol for at least 28 days, and antimicrobial agents could reduce the risk of contamination.