Abstract
Purpose: :
To compare the efficacy of commercial contact lens disinfecting solutions against two isolates of Acanthamoeba.
Methods: :
Selected Acanthamoeba isolates (HK17191 and FLA22) were grown on non-nutrient amoeba saline agar streaked with live E. coli as prey. Blocks of agar (approximately 2mm x 2mm) were cut out of the E. coli streak, each containing about 50 trophozoites and cysts. The blocks were placed in 1mL multipurpose solution (MPS) held in a 48 well tissue culture plate. For each test solution three replicates were inoculated. The MPS solutions tested were Ultra Care, Opti-free, Aquify, Renu, and Complete. An amoeba saline control was carried out for each time interval per test solution. Cells were tested for viability after MPS exposure periods of 3, 6, and 24 hours. At the end of each exposure period the agar blocks were removed from the MPS solution and placed in 1 mL of Difco Dey/Engley Broth for 5 minutes. The agar blocks were then rinsed twice in 1mL of amoeba saline, once for 5 minutes followed by a second 10 minute rinse to remove the Dey/Engley Broth. The agar blocks were placed trophozoite side down, on NNAS agar plates streaked with E. coli. The plates were sealed and incubated at room temperature for three weeks. Survival was indicated by trophozoite migration from the agar block along the prey streak.
Results: :
Percent of Acanthamoeba cultures positive for growth after exposure times of 6 and 24 hours to contact lens disinfecting systems.
Conclusions: :
After various exposure times to HK17191, UltraCare, Complete, and Aquify were most efficacious against the isolate. At various exposure times to FLA22, OptiFree and ReNu were least effective against the isolate (67% and 100% positive growth, respectively), while Aquify decreased its efficacy over time, and UltraCare and Complete improved their efficacy over time.
Keywords: amoeba • anterior segment • microbial pathogenesis: experimental studies