Ocular Microbiology and Immunology Group
Back to OMIG Main Page

2012 Agenda and Abstracts | < Previous | Next >

2012 OMIG Abstract 6

Microbial Keratitis Pathogens and Antibiotic Susceptibilities: A 5-year Review of Cases At an Urban Center in Saint Louis
R. Parihar, R. Vogel, C. Horwood, S. Edelstein
Saint Louis University Department of Ophthalmology, Saint Louis, MO

Purpose: To review the epidemiology, risk factors, microbiologic spectrum, and antibiotic susceptibilities of microbial keratitis at an urban center in Saint Louis.

Methods: Retrospective chart review of culture positive microbial keratitis cases at Saint Louis Eye Institute between January 2007 and December 2011.

Results: 64 eyes of 60 patients had culture positive corneal scrapings. Average age was 52 years (16 months–93 years), 55% of cases affected female and 45% male. Polymicrobial infection occurred in 22% (14/64) and bilateral infection in 4 cases. At least one risk factor was identified in 72% (46/64) cases, including preexisting ocular surface disease (38%), contact lens use (34%) and trauma-related (10%). The commonest pathogens isolated were gram positive bacteria (69%), followed by gram negative bacteria (24%), fungi (6%), and acanthamoeba (1%). Coagulase negative staphylococci was the most common isolate (40%), followed by S. aureus (19.5%), Pseudomonas aeruginosa (15%), Strep. pneumoniae (6%), Strep. viridians (4%), Serratia (3%) and Moraxella (3%). Subgroup analysis showed the risk factor of ocular surface disease to be more highly associated with gram positive (81%) compared with gram negative (19%) etiology. Contact lens-related infection was also most commonly associated with gram positive (52%) etiology, followed by gram negative (33%), fungi (12%), and parasites (3%). Trauma-related infection was also most commonly associated with gram positive (60%) etiology, followed by gram negative (20%), and fungi (20%).
50% of cases were on antibiotic eye drops at time of culture and 53% of these were on multiple antibiotics. Fluoroquinolones were the most commonly prescribed (51%), followed by aminoglycosides (24%), erythromycin (8%) and trimethoprim/sulfa (8%).  The rate of resistance to fluoroquinolones was 41% with S. aureus and 21% with coagulase negative staphylococci.  Other rates of resistance include 47% for erythromycin, 11% for trimethoprim/sulfa, and 4% for gentamicin among gram positive organisms. All gram negative organisms were pan-sensitive.

Conclusions: Polymicrobial infections occur not infrequently. Increased prevalence of gram positive compared with gram negative bacterial ulcers was noted.  Increased resistance to commonly prescribed antibiotic eye drops was noted, particularly the fluoroquinolones.  In light of this, caution should be applied in treating severe vision threatening infections with antibiotic monotherapy.

Disclosure: L     Sean Edelstein, MD receives lecture fees from Allergan. No financial support associated with this study.

2012 Agenda and Abstracts | < Previous | Next >