Purpose: To describe predisposing risk factors, causative microorganisms and their antibiotic susceptibility patterns in infectious keratitis during an 11-year period in Region € Orebro County, Sweden. Methods: This is a descriptive study conducted as a retrospective audit of clinical records. Patients who received treatment for infectious keratitis at any of the three ophthalmological departments within Region € Orebro County, Sweden, between 2004 and 2014 were included if they fulfilled the predefined criteria for infectious keratitis. Data regarding culture results, antibiotic susceptibility pattern and risk factors for infectious keratitis were obtained from medical records and microbiological reports. Results: In total, 398 episodes of infectious keratitis in 392 patients were included, and 285 were culture positive. The most common predisposing risk factor was contact lens wear (45%). Coagulase-negative staphylococci (39.6%) was the most commonly isolated type of organism. Staphylococcus aureus (15.1%) followed by Moraxella spp. (7.4%) and Pseudomonas aeruginosa (6.7%) were among the most common isolated bacteria not considered to be commensal. Reduced susceptibility to fluoroquinolones was observed in five of 43 S. aureus isolates and in four of nine Streptococcus pneumoniae isolates. Conclusion: The most common predisposing risk factor for keratitis was contact lens wear. Among the most common microbes, not considered to be exclusively commensals, isolated from the cornea in microbial keratitis were S. aureus, Moraxella spp. and P. aeruginosa. The antibiotic susceptibility patterns showed low proportion of resistance. Empiric treatment of suspected infectious keratitis with topical fluoroquinolones and chloramphenicol might be considered in a setting like ours pending culture results.

Infectious keratitis is a potentially sight threatening ophthalmological emergency. Contact lens wear is a common risk factor. Diagnostic advances such as MALDI-TOF MS provides new insights into the spectrum of corneal pathogens and on microbes previously considered as commensals. Corynebacterium macginleyi was described in 1995, and in 2018, the genomic features of three isolates were reported after whole-genome sequencing. Here we describe the clinical characteristics of patients with infectious keratitis (n = 29) presumably caused by Corynebacterium macginleyi, and analyze the genomic features of C. macginleyi (n = 22) isolated from the corneal ulcers of these patients. The disease course was uneventful apart from minor interventions such as corneal cross-linking and amniotic membrane transplant. Genome sequencing and comparison revealed a highly conserved core genome of C. macginleyi. Based on the analyses of single nucleotide polymorphisms, the population could be divided into two main clades that also differed in a few clade-specific genomic islands. Patients infected with an isolate belonging to the minor clade (n = 7) presented a more severe disease. Comparisons with other corynebacterial species clearly separated C. macginleyi. C. macginleyi may be considered a corneal pathogen; genomic analysis provided insights into its population structure and disease-causing potential.

ObjectiveThis study aimed to compare the efficacy of a cotton tipped applicator and a knife blade in obtaining corneal samples in patients with infectious keratitis.Methods and analysisThis is a retrospective cohort study of patients with suspected infectious keratitis during 2004–2014. Samples for corneal culture were obtained by a cotton tipped applicator and a knife blade, and directly inoculated on GC agar, blood agar and Sabouraud agar.ResultsIn all, 355 patients were included. Corneal sampling by cotton tipped applicator yielded a significantly higher rate of patients with positive corneal culture, 156/355 (43.9%), compared with knife blade, 111/355 (31.3%) (p<0.001). On a patient level, the culture results obtained by the cotton tipped applicator and the knife blade were identical in 269/355 (76%) of the patients. The overall agreement between the two instruments on microbial level was 0.66 (Cohen’s kappa 95% CI 0.60 to 0.72).ConclusionCorneal sampling by cotton tipped applicator generated a higher rate of positive corneal cultures and a higher proportion of isolated microbes than by knife blade. Future studies with randomised sampling order are needed to establish which instrument, cotton tipped applicator or knife blade, is the most effective in sampling microbes for direct inoculation in patients with infectious keratitis.

Background: To compare two different methods of corneal culture in infectious keratitis: multiple sampling for direct inoculation and enrichment (standard method) and a single sample via transport medium for indirect inoculation (indirect inoculation method). Methods: Prospective inclusion of patients fulfilling predefined criteria of infectious keratitis undergoing corneal culture according to both studied methods in a randomized order. Results: The standard method resulted in a significantly higher proportion of positive culture outcomes among the 94 included episodes of infectious keratitis (61%; 57/94) than the indirect inoculation method (44%; 41/94) (p = 0.002) and a significantly higher proportion of microorganisms than the indirect inoculation method, with a Cohen’s kappa of 0.38 (95% CI: 0.28–0.49) for agreement between the methods. Subanalysis of culture results showed that direct inoculation on gonococcal agar only combined with the indirect inoculation method resulted in a similar rate of culture positive patients and proportion of detected microorganisms to the standard method. Conclusion: Indirect inoculation of one corneal sample cannot replace direct inoculation of multiple corneal samples without loss of information. A combination of directly and indirectly inoculated samples can reduce the number of corneal samples by four without statistically significant differences in culture outcome or in the proportion of detected microorganisms.

Corynebacterium macginleyi is a slow-growing, lipid-requiring bacterium that may cause ocular infections. Here, we report the complete genome sequences of two strains, T160811 and T180208, isolated from infectious keratitis. The two genomes consist of circular chromosomes of 2,431,961 bp and 2,481,998 bp, respectively, and contain high numbers of repetitive elements.