Variable responses of Acanthamoeba strains to three multipurpose lens cleaning solutions.
OBJECTIVE
A novel method has been developed to compare Acanthamoeba strain differences by testing their susceptibility to multipurpose contact lens cleaning solutions (MPS).


METHODS
This method uses surface-attached amoebae that mimic cells attached to a contact lens. In brief, acanthamoebae were grown on non-nutrient agar plates with Escherichia coli prey. Blocks of agar with cysts or trophozoites (approximately 50 cells) were cut out and transferred to MPS [ReNu MultiPlus; (Bausch & Lomb, Rochester, NY), Complete (Allergan, Irvine, CA), and Opti-Free Express (Alcon, Ft. Worth, TX)] for up to 24 h treatment. After neutralizing in Dey Engley broth (Difco), blocks were washed in amoeba saline and reinoculated onto fresh prey bacteria. Positive growth was indicative of survival.


RESULTS
Testing showed that the efficacy of the three MPS was different. Opti-Free was the most effective against cysts, followed by ReNu while Complete was relatively ineffective. Not surprisingly, trophozoites were more susceptible than cysts.


CONCLUSIONS
Findings for individual MPS complement previous work with other methods. This study has also identified that environmental strains vary in their sensitivity to disinfecting solutions. Overall, Acanthamoeba genotypes T3, T5, and T11 from the environment were more resistant than the T4 isolates from the cornea and beach. This resilience supports previous work on temperature tolerance, in which T3 and T5, and T11 acanthamoebae grew in temperatures up to 41 degrees C. Investigators should therefore consider the strain genotype and its source before embarking on MPS sensitivity testing.
Shoff
Megan
M
Oceanographic Center, Nova Southeastern University, Dania Beach, Florida, USA. shoff.4@osu.edu
Rogerson
Andrew
A
Schatz
Scott
S
Seal
David
D
D000048:Acanthamoeba / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D015823:Acanthamoeba Keratitis / Q000382:microbiology / Q000517:prevention & control; D000818:Animals; D018639:Contact Lens Solutions / Q000494:pharmacology*; D003261:Contact Lenses / Q000382:microbiology*; D005838:Genotype; D006801:Humans
D018639:Contact Lens Solutions