Ocular pathogens and antibiotic susceptibility patterns in bacterial keratitis during 2010–2019 in the county of Östergötland, Sweden, a retrospective study

Abstract

Aim/Purpose: The aim of this study was to identify causative bacterial species, aetiology of infection and determine antibiotic susceptibility in bacterial keratitis in the county of Östergötland, Sweden.Methods: We performed a retrospective search in the regional Electronic Health Record, period 2010–2019, for patients diagnosed with keratitis according to the codes of the International Classification of Disease.Results: One‐hundred and ninety patients with lab culture‐confirmed bacterial keratitis were included in the final analysis. Antimicrobial susceptibility tests were available for all confirmed bacterial keratitis. Laboratory tests revealed a total of 188 (84%) Gram‐positive and 36 (16%) Gram‐negative pathogens. The most frequently reported bacterial species were coagulase‐negative staphylococci (CoNS) (39%), Staphylococcus aureus (17%) and Cutibacterium acnes (10%). Pseudomonas spp. was the most frequently reported Gram‐negative bacterial species (7%). Contact lens wear and severely ill/blind eye were the top two aetiological factors associated with bacterial keratitis. Most of the isolates (157 out of 173) were reported susceptible to first line antibiotics, which are fluoroquinolones, and nearly all (145 out of 155) isolates were susceptible to chloramphenicol ‐ that is the recommended treatment in combination with fluoroquinolones. We did not detect any cases of methicillin‐resistant Staphylococcus aureus. The type of treatment and the outcome of the treatment including visual acuity were assessed in the cohort.Conclusions: Our results revealed a positive rate of bacterial keratitis of 59% for the samples sent to the laboratory. The bacterial species causing keratitis in the current study were consistent over time and the species were susceptible to the recommended antibiotics. These findings indicate patients are receiving the correct treatment.