Keratitis, Acanthamoeba

Thirty thousand cases of microbial keratitis occur annually in the United States.18 Microbial keratitis encompasses bacterial, fungal, and Acanthamoeba keratitis.19 Only bacterial keratitis, the most common form, is discussed here. 

Acanthamoeba keratitis is known to be difficult to diagnosis and to treat. Most patients are initially treated fiar viral, fungal, of bacterial keratitis before the diagnosis of Acanthamoeba. Most Acanthamoeba infections are associated with contact lens wear (85% to 92%), but a smaller number are secondary to trauma. The incidence of Acanthamoeba keratitis may be greater than 1 per 30,000 contact lens wearers per year as indicated by cohort studies and questionnaires. The frequency oi Acanthamoeba keratitis in contact lens wearer may be 1 per 10,000/year or higher. 

Oral itraconazole, Ishibashi et al. reported successful treatment of 3 Acanthamoeba keratitis patients with oral itraconazole, topical miconazole, and... 

Rarely, non-Acanthamoeba amebic keratitis may present. There is limited clinical evidence that nonacan-thamoeba infections may respond to Acanthamoeba treatment. Two cases were reported of presumed non-Acanthamoeba keratitis in contact lens wearers in which the clinical presentation TesenAAeA Acanthamoeba keratitis. Nonacanthamoeba cysts (Vahlkampfia Jugosa and Naegleria) were cultured from the contact lenses. One patient responded to treatment with PHMB 0.2% and propamidine 0.1% and the other patient was lost to follow-up. 

Claerhout I, Goegebuer A,Van Den Broecke, et al. Delay in diagnosis and outcome of Acanthamoeba keratitis. Graefe Arch CUn Exp Ophthalmol 2004 242 648-653. 

Duguid IGM, Dart JKG, Morlet N, et al. Outcome of Acanthamoeba keratitis treated with polyhexamethyl biguanide and propamidine. Ophthalmology 1997 104(10) 1587-1592. 

Elder MJ, Kilvington S, Dart JKG. A cUnicopathologic study of in vitro sensitivity testing and Acanthamoeba keratitis. Invest Ophthalmol 1994 35(3) 1059-1064. 

Ishibashi Y, Matsumoto Y, Kabata T, et al. Oral itraconazole and topical miconazole with debridement for Acanthamoeba keratitis. AmJ Ophthalmol 1990 109(2) 121-126. 

Kitagawa K, Oikawa Y, Nakamura T, et al. A novel combination treatment of chlorhexidine gluconate, natamycin (primarin) and debridement for Acanthamoeba keratitis. Jpn J Ophthalmol 2003 47 616-617. 

Kosrirukvongs P, Wanachiwanawin D, Visvesvara GS, et al. Treating Acanthamoeba keratitis with chlorhexidine. Ophthalmology 1999 106(4) 798-802. 

Larkin DF, Kilvington S, Dart JK. Treatment of Acanthamoeba keratitis with polyhexamethylene biguanide. Ophthalmology 1992 99(2) 185-191. 

Mathers WD, Nelson SE, Lane JL, et al. Confirmation of confocal microscopy diagnosis oi Acanthamoeba keratitis using polymerase chain reaction analysis. Arch Ophthalmol 2000 118 178-183. 

Seal D, Hay J, Kirkness C, et al. Successful medical therapy of Acanthamoeba keratitis with topical chlorhexidine and propamidine. Eye 1996 10(4) 413-421. 

Seal HY. Acanthamoeba keratitis update—incidence, molecular epidemiology and new drugs for treatment. Eye 2003 17 893-905. 

Shama S, Garg P, Rao GN. Patient characteristic, diagnosis, and treatment of non-contact lens related Acanthamoeba keratitis. BrJ Ophthalmol 2000 84 1103-1108. 

Wysenbeek YS, et al. The reculture technique. IndividuaUzing the treatment of Acanthamoeba keratitis. Cornea 2000 19(4) 464-467. 

Acanthamoeba ocular infection was first described in 1915. Acanthamoeba keratitis can occur in both healthy and immunocompromised individuals and is initiated by contact with contaminated water. Most Acanthamoeba keratitis cases described in the mid-1980s involved daily-wear soft contact lens wearers who were using saline made from distilled water and salt tablets. Cases have also been described in extended-wear soft contact lens wearers and rigid contact lens wearers. In a survey of corneal specialists, it was found that 85% of the reported cases were in contact lens patients using primarily daily-wear or extended-wear soft lenses. 

Acanthamoeba keratitis can occur in patients other than contact lens wearers. This condition may result after corneal contamination or injury from water or vegetative matter. 

Figure 26-53 Acanthamoeba keratitis. ( 4) Active infection. (B) Ring-infiltrative pattern of late-stage infection.

The patient with Acanthamoeba keratitis typically presents with symptoms of redness, irritation, severe pain due to radial neuritis, photophobia, and reduced visual acuity. History of corneal contamination with water, saliva, or vegetative matter may be elicited with careful questioning. The duration of symptoms may vary from days to weeks, with waxing and waning of signs and symptoms common. Not infrequently, the condition has been present for weeks or months, and treatment with multiple agents for viral or bacterial keratitis had been attempted without result. 

Clinical signs of Acanthamoeba keratitis include lid edema, conjunctival injection, and usually a fluctuating anterior chamber reaction. Early in the disease course an edematous necrotic dendritiform keratitis, central or paracentral infiltration, or elevated epithelial lines may be evident. Late in the course a prominent complete or partial stromal ring-shaped infiltrate with recurrent epithelial breakdown is highly suggestive of this... 

Penetrating keratoplasty may be needed after pharmacotherapy if a visually debilitating corneal scar remains. The use of keratoplasty as a therapy for Acanthamoeba keratitis that is not responding to medical therapy is a subject of debate. It is preferable to perform the surgery when active inflammation is not present, and recurrence appears to be common if it is... 

Medications Currently Used in the Treatment of Acanthamoeba Keratitis... 

Seal D.Treatment of Acanthamoeba keratitis. Exp RevAnti-Infect Ther 2003 1 205-208. 

Radford CF, Bacon AS, Dart JK, Minassian DC. Risk factors for acanthamoeba keratitis in contact lens users a case-control study. BMJ 1995 310(6994) 1567-70. 

Uric acid nephrolithiasis calcium renal stones Malignant mesothelioma Status epilepticus Herpes simplex encephalitis Neurosyphilis Status epilepticus Cognitive dysfunction Malignant non-Hodgkin s lymphomas Treatment of PCP associated with AIDS Acanthamoeba keratitis Peripheral arterial occlusive disease Congenital or acquired protein C deficiency Respiratory distress syndrome associated with prematurity... 

Grossniklaus H.E., Waring, G.O., 4th, Akor, C., Castellano-Sanchez, A. A. and Bennett, K, 2003, Evaluation of hematoxylin and eosin and special stains for the detection of acanthamoeba keratitis in penetrating keratoplasties. American. Journal of Ophthalmology 136, 520-526. 

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