Nine-Year Trends in Antibiotic Resistance of Culture-Proven Pseudomonas aeruginosa Keratitis at a Tertiary Eye Center.

PURPOSE: The aim of this study was to evaluate the trends in antibiotic resistance among Pseudomonas aeruginosa isolates from microbial keratitis cases over a 9-year period.

METHODS

This retrospective observational study included 154 patients with culture-proven Pseudomonas aeruginosa keratitis seen between 2014 and 2022. Antibiotic susceptibility data were reviewed for fluoroquinolones, cephalosporins, beta-lactams, aminoglycosides, and other antibiotic groups. Year-wise resistance patterns were analyzed using the chi-square or Fisher exact test. Cross-sensitivity and cross-resistance between ciprofloxacin and other fluoroquinolones were also assessed.

RESULTS

Ciprofloxacin and other older-generation fluoroquinolones maintained high sensitivity (>85%) throughout the study. Moxifloxacin showed a higher resistance rate (23%), with a rising trend from 2014 (16%) to 2022 (36%), although there was a rise and dip in between. Cephalosporins showed poor efficacy, except for ceftazidime, which had a notably lower resistance rate (21%). Beta-lactam resistance was high, except for piperacillin-tazobactam. Aminoglycosides (gentamicin, tobramycin, and amikacin) exhibited the lowest resistance rates (<10%). Cross-resistance between ciprofloxacin and other fluoroquinolones was high, especially with ofloxacin and gatifloxacin.

CONCLUSIONS

Over 9 years, Pseudomonas aeruginosa isolates retained sensitivity to older fluoroquinolones and aminoglycosides, while there was a trend toward increasing resistance to moxifloxacin. Cephalosporin and beta-lactam resistance remained high, except for ceftazidime and piperacillin-tazobactam. Despite the limitations of the study, these findings support a continued role for ciprofloxacin and aminoglycosides as empiric therapy options.