Abstract
Background: The aim of this study was to consider organism patterns and antimicrobial sensitivity over a 16-year period using brain-heart infusion broth, from a district general hospital in the south-west of the UK.
Methods: This was a retrospective review of microbiological data of all cornea scrapes performed at the Royal United Hospitals, Bath, over a period from 1st January 2006 to 31st December 2022. Both direct and enrichment cultures were used. Monotherapy with a fluoroquinolone antibiotic was used as first line throughout the study period.
Results: A total of 611 cornea scrapes (323/611, 52.9% culture positive) from 524 patients, were performed in the 16-year period. Organisms cultured were bacteria in 94% (68% gram-positive, 32% gram-negative), fungi in 4.4% and Acanthamoeba in 1.6% of cases. The most identified organism was Pseudomonas aeruginosa (n=70). There was a statistically significant rise in cases of Pseudomonas aeruginosa in 2022 compared to 2019 (13/37 vs 5/41 p-value 0.01). All gram-negative bacteria were sensitive to fluoroquinolone antibiotics. 96% of gram-positive bacteria were sensitive to fluoroquinolone antibiotics, the 4% that were resistant to this, were sensitive to vancomycin.
Conclusions: A fluoroquinolone antibiotic first line appears an appropriate agent in cases of gram-negative keratitis. It is vital, however, to consider antimicrobial sensitivities especially where a gram-positive organism is identified, to allow early switching to a second line agents in resistant cases. The rise in cases of Pseudomonas aeruginosa in recent years may warrant local public health measures to help increase local community awareness on contact lens hygiene.
Keywords
Microbial keratitis, Antimicrobial sensitivity, Pseudomonas aeruginosa