SUSCEPTIBILITY OF ACANTHAMOEBA-CASTELLANII TO CONTACT-LENS DISINFECTING SOLUTIONS

A corneal isolate of Acanthamoeba castellanii was exposed to commercia l contact lens disinfecting solutions containing hydrogen peroxide, be nzalkonium chloride, polyaminopropyl biguanide, polyquaternium 1, and chlorhexidine-thimerosal. The minimum trophozoite amebicidal concentra tion and exposure times required to kill trophozoites and cysts were d etermined. Solutions containing hydrogen peroxide or chlorhexidine-thi merosal were active against both trophozoites and cysts. The benzalkon ium chloride-based solution was effective only against trophozoites. S olutions containing polyaminopropyl biguanide or polyquaternium 1 were completely ineffective. The need for adequate exposure times must be stressed.