KILLING ACANTHAMOEBAE WITH POLYAMINOPROPYL BIGUANIDE - QUANTITATION AND KINETICS

The two Acanthamoeba species most often implicated in corneal keratiti s, A. castellanii and A. polyphaga, were exposed as cysts to polyamino propyl biguanide (PA-PB), a commonly used antimicrobial agent. Killing of amoeba cysts was rapid and extensive, with fewer than 2% of either species surviving 30 s of exposure to greater-than-or-equal-to 45 ppm of PAPB. Killing kinetics were biphasic, and further exposures of 15 min to 1 h killed greater than 90% of those surviving initial killing. This potency of PAPB, together with its low toxicity to humans when i ngested or applied topically, underscores the potential of PAPB as an antiamoebic agent.