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D. Miller, A. Iovieno, D. Ledee, E. Alfonso; Culture and Molecular Recovery of Co-Pathogens and Endosymbionts Among Patients With Amebic Keratitis. Invest. Ophthalmol. Vis. Sci. 2009;50(13):856.
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Acanthamoeba are ubiquitous in nature and known to harbor pathogenic microorganisms including bacteria, fungi, viruses and other parasites. Co-infection with any of these during Acanthamoeba keratitis may play a role in the difficult diagnostic and protracted clinical course associated with this disease. The purpose of this study was to determine the frequency and spectrum of co-pathogens and endosymbionts recovered from cases of culture proven Acanthamoeba keratitis at a tertiary referral center.
Microbiology records of patients presenting from January 1987-November 2008 with culture proven Acanthamoeba keratitis (N=150) were reviewed for presence of co-pathogens. Acanthamoeba isolates from 22 patients collected in 2007 were evaluated by PCR to document the presence of microbial endosymbionts/co-pathogens.
Acanthamoeba cases ranged from 1-7% of keratitis cases during the 22 year period. Number of cases/year ranged from 3-28 with an average of 6.8.Twenty-nine (29) co-pathogens and or endosymbionts were confirmed in 17.3% (26/150) of cases. Co-pathogens were recovered in 7.3% of cultures (11/150).The most common pathogens included gram positives- 45.4% (5/11-P. acnes-3, Coagulase negative staphylococci -1, S. viridans group-1), gram negatives-36.4% (4/11-S. marcescens-2, P. mirabilis-1, Capnocytophaga sp.-1), HSV-1 (9.1%) and Fusarium sp.-1 (9.1%). Endosymbionts (N=18) were documented in 68.2% (15/22) of isolates using PCR. Pathogen spectrum included Mycobacterium species-9 (50%), P. aeruginosa-4 (22.2%), Legionella sp.-3 (16.7%), P. putida-1 (5.6%) and C. trachomatis-1(5.6%). Patients infected with Acanthamoeba harboring endosymbionts (N=15) took significantly longer to resolve (110 days vs 56 days, p=0.000) than those without endosymbionts.
Mixed infections maybe more common than recognized in patients presenting with Acanthamoeba keratitis. Presence of co-pathogens and or endosymbionts during Acanthamoeba infections may impact clinical course, tissue damage and therapeutic options.
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