Abstract
Purpose: :
To determine the risk factors and optimal detection methods for Acanthamoeba keratitis at the New York Eye and Ear Infirmary (2005-2007).
Methods: :
The medical records of 23 cases of Acanthamoeba keratitis from 2005-2007 were collected. The records were reviewed and the following information was tabulated: patient demographics, medical history, risk factors for Acanthamoeba keratitis (including contact lens usage, cleansing solution used, overnight usage, method of cleansing, trauma, etc.), mode of detection, culture media employed, and clinical outcomes.
Results: :
Of the 23 cases, 21 presented after October 2006. Nineteen cases were related to contact lens usage, 3 cases were related trauma, and 1 case was related to contaminated water exposure without lens usage. Of the 2 cases presenting prior to October 2006, 1 case was related to trauma and the other to contact lens usage. Both were diagnosed by corneal pathology sections. Of the cases presenting after October 2006, 11/21 (52.4%) had positive corneal cultures, 10/21 (47.6%) had visible cysts by confocal microscopy, and 17/21 (71.0%) were diagnosed by the combination of cultures and/or confocal microscopy. Six cases were diagnosed by slit exam, history, and response to anti-amoebic therapy alone. All 11 cases with positive cultures were detected after October 2006 after switching culture media from a non-nutrient agar with E. coli overlay to one with Enterobacter aerogenes. Of the 19 cases related to contact lens usage, 7/19 (37%) used AMO Complete® cleansing solution, 5/19 (26.3%) used Bausch & Lomb Moisture Loc® solution, and 1/19 used both of these solutions. Risk factors included overnight contact lens usage (4/19), exposure to contaminated water (5/19), extended contact lens usage (greater than 12 hours per day) (4/19), and infrequently replenishing solution between contact lens usage (2/19).
Conclusions: :
Our Acanthamoeba outbreak began in October of 2006 nearly 18 months after those reported in Philadelphia and Chicago. Corneal culture and confocal microscopy seem to be very effective modes of detection. Switching to an Enterobacter aerogenes overlay instead of E. coli dramatically improved our culture yield (~50%). There was an association between the type of contact lens solution a patient used and the acquisition of Acanthamoeba keratitis.
Keywords: Acanthamoeba • cornea: stroma and keratocytes • cornea: clinical science