Isolation and in vitro susceptibility of Acanthamoeba from a patient with keratitis.
The acanthamoebae are facultative parasites of man, and may infect the brain, skin, bone, respiratory passages and eyes. Over the past several years, Acanthamoeba keratitis has become a growing problem. This is the first case isolating Acanthamoeba polyphaga from a corneal biopsy of an ophthalmic patient in Taiwan. Direct impression smear by trichrome stain gave positive result. To provide effective clinical treatment, chemotherapeutic agents available for ophthalmic use were tested for its susceptibility with a microtiter plate method. Reading at 24- and 48-hour intervals, only amphotericin B, clotrimazole and neomycin-polymyxin B had an MIC (minimal inhibition concentration) lower than 1,000 micrograms/ml. If reading interval was prolonged to one week, neomycin, 5-flucytosine and gentamicin also showed appreciable activity. Amoebicidal concentrations (AC) and cysticidal concentrations (CC) were much higher than MIC. Only neomycin-polymyxin B, neomycin, and amphotericin B of high concentration were proved to be cysticidal.