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M.D. Hammond, K.S. Bower, R.D. Stutzman, W.Y. Ellis, B.M. Mitchell, S.G. Barnes, E.R. Morris, F.O. Tuamokumo; In vitro Susceptibility of Acanthamoeba Species to WR99210, WR096268 and Analogs . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2784.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the efficacy of a new class of anti–folate drugs, WR99210, WR096268 and related analogs, against Acanthamoeba species in vitro. Suspensions of mature Acanthamoeba cysts (final concentration of 104 cysts/mL) were prepared from stock strains of corneal Acanthamoeba isolates. 100 µL of the standardized Acanthamoeba cyst suspension was exposed to serial dilutions of WR99210, WR096268 and related compounds from the Walter Reed repository, polyhexamethaline biguanide (PHMB), chlorhexidine, as well as positive and negative controls. After 48 hours, the cysts were washed to remove the drugs and re–plated on non–nutrient agar with inactivated E. coli overlay. The plates were incubated at 30 degrees Celsius and examined daily for the appearance of trophozoites. Minimum cysticidal concentrations (MCC), defined as the lowest concentration of the drug that resulted in no recovery of Acanthamoeba after 7 days of incubation, were determined for each compound. WR99210 and WR096268 showed effective cysticidal activity at higher concentrations with MCC of 800 µg/ml and 200 µg/ml, respectively. In contrast, one compound in particular, BK1845, showed excellent cysticidal activity that approached or equaled PHMB and chlorhexidine with a MCC of 3.12 µg/ml. WR99210, WR096268 and analogs are effective against ocular Acanthamoeba isolates in vitro. Although most of the analogs we tested were effective at concentrations considerably higher than the current standards, PHMB and chlorhexidine, BK1845 appears particularly effective and warrants further investigation as a potential new line of therapy.
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