Ocular Pathogens and Antibiotic Sensitivity in Bacterial Keratitis Isolates at King Khaled Eye Specialist Hospital, 2011 to 2014.

BACKGROUND

To investigate prevalence and in vitro susceptibility trends of bacteria isolated from patients with bacterial keratitis from 2011 to 2014 in a tertiary care eye hospital in Saudi Arabia.

METHODS

Retrospective review of bacterial isolates from corneal scraping of eyes with microbial keratitis. The most common isolates and their antibiotic resistance profiles were identified; trend analysis was performed over the study period.

RESULTS

A total of 2037 bacterial isolates met inclusion criteria during the study period. Gram positives accounted for 91.4% of isolates, including Staphylococcus epidermidis 962 (27.4%), other coagulase-negative staphylococci 289 (8.2%), Staphylococcus aureus 237 (6.8%), and Streptococcus pneumoniae 159 (4.5%). Pseudomonas aeruginosa was the most common gram-negative isolate (38.4%). All tested Gram positive isolates were sensitive to vancomycin. As a whole, isolates were most sensitive to moxifloxacin and ciprofloxacin with resistance of 3.7% and 3.3%, respectively. Oxacillin resistance was increasingly found in S. aureus (14.8% in 2011, 27.8% in 2014, P = 0.06), but was without significant change in S. epidermidis and other coagulase-negative Staphylococci (range 19.4%-32.0%). There was an increase in moxifloxacin resistance among S. epidermidis, increasing from 0.9% to 12.7%. Using a logistic regression model, the overall change in resistance of bacteria to antibiotics by year was not significant.

CONCLUSIONS

Gram-positive bacteria represented the majority of bacteria isolated, with a possibly increasing prevalence of oxacillin resistance in S. aureus. Fluoroquinolone resistance is uncommon, and no vancomycin-resistant gram-positive strains were identified. There was no overall significant trend in antibiotics resistance; however, future surveillance studies are recommended.