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Hugo Y Hsu, Sean Edelstein; 15 Years of Microbial Keratitis at an Urban University Practice in Saint Louis: The Isolates. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):4072.
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© ARVO (1962-2015); The Authors (2016-present)
<br /> The spectrum of micro-organisms causing infectious keratitis varies between geographic areas and through time. We wish to identify the isolated micro-organisms from infectious keratitis cases and to observe any trends in the spectrum of causative organisms over a 15-year period at Saint Louis University’s Department of Ophthalmology.
<br /> We searched the database of the microbiology department and the diagnosis database of the ophthalmology department at Saint Louis University to identify cases of microbial keratitis from 1999-2013. Records of culture-positive cases were reviewed retrospectively. Non-contaminant isolates were tabulated into three 5-year periods (1999-2003; 2004-2008; and 2009-2013) and compared.
<br /> 229 non-contaminant isolates were identified: 45 from 1999-2003; 84 from 2004-2008; and 100 from 2009-2013. Overall, Gram-positive organisms were the most commonly isolated (47%) followed by Gram-negative organisms (34%). Fungi represented 18% of the overall isolates. Separated into the three 5-year periods, Gram+ organisms represented 53%, 44%, and 46% of the total; Gram- represented 38%, 27%, and 33% of the total; and fungal organisms represented 9%, 20%, and 20% of the total. Pseudomonas was the most commonly isolated organism overall (21%) as well as in each of the 3 time periods. Streptococcus species were the next most common isolates overall (15%) followed by coagulase-negative staphylococcus and Staphylococcus aureus (14% each). The percentage of Staphylococcus aureus isolates that were oxacillin-resistant (ORSA) increased in each of the three 5-year periods from 22% to 44% to 69%.
<br /> The number of non-contaminant isolates increased in each of the three 5-year periods. Pseudomonas was the most common isolate found in infectious keratitis at Saint Louis University over the 15-years period. The two biggest changes we observed were in the number and percentage of fungal isolates as well as the increase in the proportion of ORSA isolates over time. Fungal organisms accounted for 9% of isolates at the start of the 15-year period but then doubled to 20% during the mid 2000’s and continued through the end of the 15-year period in 2013. The percentage of ORSA isolates tripled over the 15 years period.
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