SUMMARYTrophozoites and cysts of 20 isolates of Acanthamoeba from the cornea and five from related samples were tested in vitro for sensitivity to ten drugs (three aromatic dia midines, two aminoglycosides, two macrolides, a polyene macrolide antibiotic, an organoarsenical and an anti metabolite) and two cationic antiseptics (chlorhexidine and polyhexamethylene biguanide, PHMB). Keratitis associated with Acanthamoeha infection is a relatively rare, sight-threatening condition occurring most often in contact lens wearers, I where there has been inappropriate or inadequate disinfection of contact lens systems." The clinical presentation of the disease is often mistakenly diagnosed as herpes simplex or fungal infec tion.3 This results in inappropriate anti-microbial agents being administered. Early features4-6 such as pain, photo phobia and recurrent epithelial breakdown with little infil-

SummaryThirty cases of microbial keratitis after penetrating keratoplasty were reviewed to examine the associated risk factors, the spectrum of pathogens and the prognosis for graft survival and visual outcome.The indications for keratoplasty in this group differed markedly from those for all corneal grafts performed with a much higher incidence of previous microbial kera titis and of herpes simplex keratitis.A positive culture was obtained in 93% of cases and in contrast to microbial kera titis overall, Gram positive organisms predominated particularly streptococcus pneumoniae and staphlycoccus aureus.Risk factors identified were loose or broken sutures, graft decompensation and a poor ocular surface environment.There was a poor prognosis for graft survival with only 23% of cases retaining a clear graft. Overall 53% of cases were regrafted. A positive culture was defined as growth of more than one colony of an organism in the inoculating streak of any culture medium.In most cases multiple colonies were grown. Culture media routinely used were blood agar, Sabouraud's medium, thioglycol late medium, nutrient broths and where indi cated Eschrichia Coli seeded non-nutrient agar for Acanthamoeba.

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