A CLINICOPATHOLOGICAL STUDY OF IN-VITRO SENSITIVITY TESTING AND ACANTHAMOEBA-KERATITIS

Purpose. To examine the extent of any correlation between the in vitro sensitivity and the clinical outcomes of Acanthamoeba keratitis. Meth ods. The clinical outcomes were correlated with the in vitro sensitivi ty of 23 isolates of 23 patients with culture-positive Acanthamoeba ke ratitis. The laboratory assay assessed the amoebicidal and cysticidal efficacy of 13 drugs. Results. Most agents were effective against the trophozoites in vivo. Polyhexamethylene biguanide (PHMB) and chlorhexi dine were the most successful cysticidal agents, followed by sepazoniu m and propamidine. Clotrimazole, paramomycin, and ketoconazole were cy sticidal in a few specimens, but usually in high concentrations. Neomy cin was ineffective against cysts in vivo. Nineteen patients were trea ted with topical propamidine and neomycin, and a medical cure was obta ined in nine (47%). There was poor correlation between the clinical ou tcomes of individual cases and the in vitro sensitivity testing. The m edical failures were treated with topical PHMB and propamidine and eig ht of ten (80%) of these were medically cured. Two patients, however, were still culture positive after 28 and 41 weeks of treatment. PHMB h as an excellent in vitro sensitivity profile, but the two cases of fai lure were sensitive to the drug and resistance had not developed. Conc lusions. In vitro sensitivity testing has been important in the screen ing of new agents, although disappointing in the management of individ ual cases in this set of studies.