Abstract
Purpose :
The purpose of this study was to review the spectrum of disease and antibiotic susceptibilities of bacterial keratitis at a major tertiary care referral eye center in central Virginia.
Methods :
Medical records of all patients with microbial keratitis from January 1, 2010, to September 30, 2015, at the University of Virginia Health System were reviewed.
Results :
A total of 282 cases of presumed bacterial keratitis were analyzed. 164 (58%) cases were cultured. Of the 164 cases cultured, 81 (49%) showed positive results. Seventy-three (90%) were positive for bacteria and 8 (10%) were positive for fungus. Gram-positive bacteria were found in 62% of bacterial-proven cultures. Of the gram-positive bacteria, coagulase-negative Staphylococcus was most common at 33%; Streptococcus pneumonia and Staphylococcus aureus were the next most common at 16% and 12%, respectively. Pseudomonas aeruginosa was the most common gram-negative bacteria isolated at 57% of all gram-negative isolates. Contact lens wear was found in 53% of the bacterial keratitis cases. The most common organism in contact lens-associated bacterial keratitis was P. aeruginosa (48%). In non-contact lens-related ulcers, the most common organism was coagulase-negative Staphylococcus (25%). P. aeruginosa showed no resistance to ciprofloxacin, levofloxacin and moxifloxacin. Moxifloxacin was not tested against any other gram negative bacteria. There were no cases of resistance of gram-positive bacteria to moxifloxacin, although there were no cases of S. aureus tested against moxifloxacin. 43% of S. aureus was resistant to Oxacillin, and 60% of S. aureus was resistant to levofloxacin. No organisms tested were resistant to gentamicin, tobramycin or vancomycin.
Conclusions :
Gram positive bacteria are the most common cause of bacterial keratitis at our institution. However, among contact-lens wearers, P. aeruginosa is the most common organism. There was no resistance of P. aeruginosa to fluoroquinolones. S. aureus was found to have a high rate of resistance to oxacillin. Although no cases of S. aureus were tested against moxifloxacin it was found to have a high rate of resistance to a third-generation fluoroquinolone, levofloxacin. This could signify a therapeutic challenge since fluoroquinolones are increasingly used as first-line monotherapy. No organisms tested were resistant to gentamicin, tobramycin or vancomycin. Fungal ulcers constituted 10% of our culture-positive keratitis.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.