Shifting trends in bacterial keratitis in Taiwan: A 10-year review in a tertiary-care hospital

Purpose: To investigate the distribution, current trends, and antibiotic susceptibility profiles of bacterial keratitis isolates over 10 years. Methods: We retrospectively reviewed the microbiology records of all corneal scrapings undertaken for cultures at Chang Gung Memorial Hospital from 2003 through 2012. We identified bacterial isolates and verified antibiotic susceptibilities by using the disk diffusion method. The Mantel-Haenszel linear-by-linear association x2 test was used to detect the trends. Results: We collected 2012 corneal scrapings, and the culture was positive in 992 samples (49.3%), yielding 1282 isolates. Bacterial isolates were identified for 1039 isolates (81.1%), including 533 grampositive and 506 gram-negative isolates. An increase in the percentage of gram-positive isolates was significant (P = 0.008), as was a decrease in that of gram-negative isolates (P = 0.002). The most common bacterial isolates were Pseudomonas aeruginosa (24.4%) and coagulase-negative Staphylococcus (16.6%). For gram-positive organisms, the susceptibilities were as follows: vancomycin 100%, ciprofloxacin 88.9%, sulfamethoxazole-trimethoprim 86.8%, clindamycin 73.2%, and oxacillin 56.5%. The susceptibility of gram-positive bacteria to clindamycin and oxacillin increased significantly (P = 0.009 and P = 0.001). For gram-negative organisms, the susceptibilities were as follows: ciprofloxacin 93.7%, piperacillin 91.9%, ceftazidime 90.9%, amikacin 88.3%, and gentamicin 84.7%. No change in trend occurred. Conclusions: In Taiwan, we documented an increasing trend in the percentage of gram-positive bacteria. Methicillin-resistant microorganisms accounted for 43.5% of all gram-positive bacteria, but the trend of resistance to oxacillin and clindamycin significantly decreased. Ciprofloxacin continued to be a good empiric antibiotic for treating bacterial keratitis.