Co-incubation of Acanthamoeba castellanii with strains of Pseudomonas aeruginosa alters the survival of amoeba

Enhanced survival of Acanthamoeba castellanii has previously been reported following co-incubation with a single strain of Pseudomonas aeruginosa. The aim of this study was to evaluate the impact of different strains of P. ae ruginosa on amoebae survival. Four contact lens solutions were challenged w ith A. castellanii for between 6 and 24 h, and survival rates of amoeba wer e calculated. Subsequently, A. castellanii was co-incubated with different strains of P. aeruginosa (strain 6294, an invasive isolate; 6206, a cytotox ic isolate; and Paer 001, a null isolate). Differences in amoeba survival o ver time between solutions for each bacterial strain were analysed. Non-neu tralized hydrogen peroxide was the most effective system against A. castell anii at all time points (P < 0.05). Survival rates were not different betwe en multipurpose solutions and neutralized hydrogen peroxide. Co-incubation with P. aeruginosa altered amoeba survival, and maximum survival occurred i n the presence of the invasive strain of P. aeruginosa. Enhanced amoeba sur vival may occur in the presence of certain strains of Gram-negative bacteri a, and with certain types of contact lens disinfection systems.