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10-year analysis of microbiological profiles and in vitro antimicrobial susceptibility: the Kent microbial keratitis study

Eye (2026)Cite this article

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Abstract

Background

To evaluate the incidence, microbiological profile, and in vitro antimicrobial susceptibility patterns of microbial keratitis (MK) in Kent over a 10-year period.

Methods

A retrospective analysis was conducted of all corneal scrape specimens processed between January 2015 and August 2024 at Maidstone and Tunbridge Wells NHS Trust and East Kent Hospitals University NHS Foundation Trust. Data extracted included patient demographics, isolates, and antimicrobial sensitivities. The study period was divided into two time periods (2015–2019 and 2020–2024) for trend analyses.

Results

The estimated mean incidence of MK was 2.2 per 100,000 population per year. Of 1029 scrapes, 384 were culture-positive (37.3%). Gram-negative organisms predominated (50.9%), followed by Gram-positive (37.8%), fungi (5.0%), and Acanthamoeba (6.3%). Polymicrobial infections accounted for 10.4% of cases. Pseudomonas spp (35.9%), Coagulase-negative Staphylococci (15.0%), and Staphylococcus aureus (9.8%) were most commonly isolated. Average susceptibility of Gram-positive organisms to chloramphenicol, fluoroquinolones, and gentamicin was 96.7%, 76.0% and 92.1%, respectively, and for Gram-negative organisms was 48.2%, 93.4%, and 99.3%, respectively. Concerning trends included a 16.9% reduction in fluoroquinolone susceptibility among Gram-positive isolates (p < 0.001), with moxifloxacin efficacy decreasing by 57.9% (p = 0.002). The prevalence of Acanthamoeba represents an unrecognised regional disease burden, exceeding other UK regions (1.1–4.8%).

Discussion

This study identified a marked decline in fluoroquinolone susceptibility among Gram-positive organisms and a significantly higher acanthamoeba prevalence compared to other UK regions and global reports. These findings highlight the importance of ongoing antimicrobial stewardship and support re-evaluation of empiric treatment protocols for MK in Kent.

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Fig. 1: Annual number and incidence of microbiologically-confirmed MK cases in Kent (2015–2024).

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Data availability

The data collected and analysed in this study contains sensitive information and is therefore not publicly accessible. However, researchers may contact the corresponding author to request access to the dataset subject to appropriate review.

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Acknowledgements

The authors gratefully acknowledge Dr. Dimitrios Mermerelis (Consultant Microbiologist, Maidstone and Tunbridge Wells NHS Trust), Sarah Sparks (Senior Biomedical Scientist, Maidstone and Tunbridge Wells NHS Trust), and Felicity Ryan (Principal Clinical Scientist, East Kent Hospitals University NHS Trust) for their invaluable expertise in refining the microbiological methods descriptions during peer review, and enhancing our understanding of laboratory aspects of microbial keratitis.

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Authors and Affiliations

  1. Maidstone General Hospital, Hermitage Lane Ln, Maidstone, UK

    Imran Karim Janmohamed, Oluwadamilola Oguntoye, Mohamed Elalfy & Sundas Maqsood

  2. East Kent Hospitals University NHS Foundation Trust, Ethelbert Rd, Canterbury, UK

    Lanxing Fu & Chloe Robson

  3. Corneoplastic Unit and Eye Bank, Queen Victoria Hospital NHS Foundation Trust, East Grinstead, UK

    Mohamed Elalfy

  4. Cornea Unit, Research Institute of Ophthalmology, Giza, Egypt

    Mohamed Elalfy

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  1. Imran Karim Janmohamed
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  6. Sundas Maqsood
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Contributions

IKJ conceptualised and designed the study. IKJ, OO, and CR collected the data. IKJ wrote the manuscript for publication. LF performed the statistical analyses. SM, LF, and ME provided expert input and commentary on the manuscript.

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Correspondence to Sundas Maqsood.

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Janmohamed, I.K., Oguntoye, O., Fu, L. et al. 10-year analysis of microbiological profiles and in vitro antimicrobial susceptibility: the Kent microbial keratitis study. Eye (2026). https://doi.org/10.1038/s41433-026-04302-w

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