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2012 Agenda and Abstracts | < Previous

2012 OMIG Abstract 24

Evaluation of a Complete-Kill Assay for Anti-Acanthamoeba Solutions
R.P. Kowalski, S. Abdel Aziz, R.M.Q. Shanks, E.G. Romanowski, A.C. Nau

The Charles T. Campbell Ophthalmic Microbiology Laboratory, University of Pittsburgh, Pittsburgh, PA

Purpose: Acanthamoeba keratitis is a sight debilitating disease that requires effective topical drug therapy to eradicate the pathogenic agent. We compared four anti-acanthamoeba drugs using a complete-kill assay.

Methods: An assay was created to determine whether 0.02% poly(hexamethylene biguanide) hydrochloride (PHMB), 0.02% chlorhexidinedigluconate (CHL), 0.1% c-desomedine (DESO), and 1.0% c-voriconazole (VOR) were effective in completely killing 15 different isolates of acanthamoeba at time points 24, 48, and 72 hours in comparison to a saline control. Each 0.5 ml volume of solution was inoculated with 0.1 ml of acanthamoeba cysts at a concentration of 1-5 x 106/ml determined with a hemacytometer and allowed to incubate at 30oC. At the time points listed, aliquots from each treatment group were inoculated onto non-nutrient agar overlaid with Enterobacter aerogenes. The plates were microscopically examined for growth at time points 1 and 2 weeks. At 2 weeks, all plates were sub-cultured onto fresh medium. At 7 days, growth in sub-culture at each time point was graded 1 for growth and zero for no growth. The time points were combined for each drug with a possible grade from 0 to 3. The grades were non-parametrically (Mann Whitney) compared to determine any significance in positive growth between the drugs.

Results: Complete–kill was determined more frequently with PHMB and DESO (p=1.0) than CHL (p=0.04). PHMB, DESO, and CHL demonstrated more complete-kill than VOR (p=0.01) which was more effective than the saline control (p=0.0003).

Conclusion: The complete-kill assay appears to provide separation in the effectiveness of different anti-amoebic drug solutions. This assay may provide an alternative evaluation of possible new anti-infectives in the treatment of acanthamoeba keratitis.

Disclosure: None

2012 Agenda and Abstracts | < Previous