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Michelle Peng, Vicky Cevallos, Jennifer Rose-Nussbaumer; Bacterial Keratitis: Isolated Organisms and Antibiotic Resistance Patterns. Invest. Ophthalmol. Vis. Sci. 2016;57(12):341.
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© ARVO (1962-2015); The Authors (2016-present)
Corneal opacities, which are often caused by infectious keratitis, are the fourth leading cause of blindness worldwide. Initial therapy is often empiric until gram stain and culture results become available. The use of commercially available fourth generation fluoroquinolones versus compounded fortified antibiotics for the initial treatment of infectious keratitis has been widely debated. In this study we would like to determine the spectrum of bacterial organisms cultured from corneal samples at a tertiary care eye center in Northern California, as well as their antibiotic sensitivities.
Retrospective chart review of 526 positive corneal cultures performed and processed at the University of California, San Francisco Proctor microbiology laboratory from 1999 to 2015. Cultures were performed in a standardized manner by inoculating blood, chocolate, and sabouraud culture plates. Antibiotic sensitivities of microbiological isolates were performed according to guidelines set forth by the Clinical and Laboratory Standards Institute.
Isolated organisms were gram positive in 347 (66%) with the most common being methicillin-sensitive staphylococcus aureus (31%, N =108). One hundred seventy-nine were gram negative (34%) with pseudomonas aeruginosa as the most prevalent organism (28%, N=50). Overall, most gram-negative organisms had a high level of susceptibility to moxifloxacin. Sensitivity of gram-positive organisms to moxifloxacin was more variable ranging from 70% to 100% for most organisms. In particular methacillin-resistant staph aureus susceptibility to moxifloxacin in vitro was low at 14% (N=3).
Gram-positive organisms are the most commonly identified etiology of microbial keratitis in this series. We found variable in vitro sensitivity to moxifloxacin among gram-positive organisms.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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