COMPARISON OF AXENIC AND MONOXENIC MEDIA FOR ISOLATION OF ACANTHAMOEBA

Acanthamoeba is a genus of ubiquitous, free-living amebae that can be difficult to isolate by standard microbiologic techniques, We retrospe ctively reviewed the laboratory records of patients with ocular acanth amoebic infection for the period from January 1973 to June 1996 and fo und that Acanthamoeba isolates were recovered from 73, 71, and 70% of clinical specimens inoculated onto buffered charcoal-yeast extract aga r (BCYE), nonnutrient agar with live or dead Escherichia coli, and try ptic soy agar (TSA),vith horse or sheep blood, respectively, We then p rospectively compared the recovery of a corneal isolate of Acanthamoeb a on commercial media from Remel and BBL (TSA with 5% sheep blood, TSA with 5% horse blood, TSA with 5% rabbit blood, V agar, chocolate agar , BCYE, and selective BCYE with polymyxin B, anisomycin, and vancomyci n) and on axenic and monoxenic media prepared with live or dead bacter ia (Enterobacter aerogenes, E. coli, Klebsiella pneumoniae, Pseudomona s aeruginosa, Serratia marcescens, Staphylococcus aureus, and Stenotro phomonas maltophilia). Good recovery of trophozoites was obtained on B CYE, TSA with rabbit blood, TSA with horse blood, and Remel TSA with s heep blood, BBL TSA with horse blood or rabbit blood provided good rec overy of cysts, All species of live or dead bacteria yielded good reco very of trophozoites; however, only nonnutrient agar with live P. aeru ginosa, live E. aerogenes, or live S. maltophilia gave good recovery o f cysts, TSA with either rabbit blood or horse blood, BCYE, and nonnut rient agar prepared with live P. aeruginosa, E. aerogenes, or S. malto philia offer optimal recovery of Acanthamoeba.