Comparative in vitro effectiveness of a novel contact lens multipurpose solution on Acanthamoeba castellanii

Background A multipurpose contact lens cleaning solution (MPS) containing novel active ingredients under development was compared to two commercially available MPS solutions for effectiveness against Acanthamoeba isolates. Methods The Acanthamoeba isolate A . castellanii was propagated for trophozoite or cyst-containing cultures for the purpose of assessment of effectiveness of each MPS. An alamar blue-based cellular respiration assay was used to assess effectiveness against trophozoites; Trypan blue hemocytometer-based microscopic counts measured cysticidal effects. To assess the general antimicrobial potency of each solution as controls for the anti-amoebic assays, comparative bactericidal effectiveness using Serratia marcenses was also performed. Results Minimal effectiveness against either Acanthamoeba form was observed from either commercial MPS. In contrast, the novel MPS achieved complete kill within 1 h contact time for both Acanthamoeba trophozoite and cysts. Each commercial MPS required 6 h contact time to achieve a two to three log reduction in S . marcenses . In contrast, the experimental MPS achieved disinfection in 60 min contact time, and complete kill (