Purpose: To investigate the antibiotic susceptibility as well as the clinical, epidemiological, and microbiological profiles of microbial keratitis.
Methods: This was a longitudinal retrospective study, and we retrospectively reviewed medical and laboratory records from 2015 to 2019.
Results: In total, 380 pathogens (321 bacteria and 59 fungi) were isolated from the corneas of 352 patients. Staphylococcus species (45%) were most abundant within the organisms that were isolated, followed by Pseudomonas (18.4%), fungi (15.5%), Streptococcus (7.9%), and Serratia species (3.2%). The isolated gram-positive bacteria were not resistant to amikacin or vancomycin, although 14.8% of the gram-positive isolates were resistant to ciprofloxacin (p<0.05). All the gram-negative isolates were susceptible to amikacin. Male patients represented 62.8% of the 129 cases with accessible clinical data. The mean age of the patients was 53.17 ± 21 years. The time to presentation (from onset of symptoms) was 14.9 ± 19.4 days (median: 7 days). Large ulcers (>5 mm in any dimension) were present in 49.6% (64 eyes) of the cases. The duration of treatment was 49 ± 45.9 days (median: 38 days). Direct ocular trauma was reported by 48 (37.2%) patients, and 15 patients (11.6%) reported using contact lenses. For 72 (55.8%) patients, topical treatment had been previously prescribed, and 16 (12.4%) patients reported using other classes of drugs. Hospitalizations were required for 79 (61.2%) patients, and in terms of major complications, 53 (41.1%) patients had corneal perforations. A total of 40 patients (31%) underwent tectonic penetrating keratoplasty, and 28 (21.7%) developed secondary glaucoma. A progression to endophthalmitis occurred in 8 (6.2%) patients, with 50% of those patients' (3.1% of the total) endophthalmitis evolving to evisceration. The patients' microbial keratitis was largely treated empirically, with 94 (72.9%) patients prescribed moxifloxacin and 56 (43.4%) prescribed ciprofloxacin before receiving their culture results.
Conclusions: For the most part, our hospital treated patients with severe microbial keratitis. Despite identifying gram-positive bacteria in most of the isolates, we also frequently identified gram-negative rods and fungi. Our susceptibility results support prescribing a combination of vancomycin and amikacin as an effective empirical therapeutic regimen to treat microbial keratitis.