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Association Between Season, Temperature and Causative Organism in Microbial Keratitis in the UK
Andrew Walkden1, Catherine Fullwood2,3, Shi Zhuan Tan1
1Cornea Department, Manchester Royal Eye Hospital, Manchester, United Kingdom.
Purpose:
Microbial keratitis (MK) is a major cause of corneal blindness worldwide. Variations in season and temperature can affect MK incidence due to specific causative organisms; however, few studies have examined these factors in the UK.
Methods:
Retrospective review of all corneal scrapes from patients with MK presenting to Manchester Royal Eye Hospital, UK, between January 2004 and December 2015. Manchester's monthly temperature data were obtained from Met Office UK. Analysis was performed using logistic regression.
Results:
From 4229 corneal scrapes, 1539 organisms grew (90.6% bacteria, 7.1% fungi, and 2.3% Acanthamoebae sp.). Gram-positive bacteria grew with increasing temperature [odds ratio (OR) 1.62, 95% CI: 1.11-2.39, P = 0.014], and fungi grew with decreasing temperature (OR 0.29, 95% CI: 0.16-0.51, P < 0.001). Moraxella sp. grew with decreasing temperature (OR 0.91, 95% CI: 0.86-0.96, P = 0.001). Compared with winter, overall culture positivity was significantly less likely in summer (OR 0.57, 95% CI: 0.38-0.87, P = 0.008) and spring (OR 0.65, 95% CI: 0.43-0.99, P = 0.045). Gram-negative bacteria were more likely in summer (OR 1.48, 95% CI: 1.06-2.09, P = 0.022) and autumn (OR 1.75, 95% CI: 1.24-2.47, P = 0.001). Candida sp. were less likely in summer (OR 0.25, 95% CI: 0.07-0.82, P = 0.027) and autumn (OR 0.18, 95% CI: 0.05-0.62, P = 0.009), and Acanthamoeba sp. were less likely in summer (OR 0.39, 95% CI: 0.15-0.92, P = 0.037) and spring (OR 0.26, 95% CI: 0.08-0.69, P = 0.011).
Conclusions:
Herein we report variation in the incidence of MK-causing organisms by season and temperature; this finding may aid clinicians in predicting possible causative organisms for MK at differing times of the year.
Insights
Seasonal variations influence microbial keratitis (MK) causes in the UK. Warmer temperatures correlate with Gram-positive bacteria, while cooler weather favors fungi and Moraxella species, aiding clinical prediction.
Area of Science:
- Ophthalmology
- Microbiology
- Environmental Health
Background:
- Microbial keratitis (MK) is a significant global cause of corneal blindness.
- Environmental factors like season and temperature may influence the incidence of MK by affecting specific causative organisms.
- Limited research exists on these seasonal and temperature-related variations in MK within the UK.
Purpose of the Study:
- To investigate the relationship between season, temperature, and the incidence of various microbial organisms causing MK in the UK.
- To determine if seasonal patterns exist for specific pathogens responsible for microbial keratitis.
Main Methods:
- A retrospective analysis of corneal scrape data from MK patients at Manchester Royal Eye Hospital (2004-2015).
- Correlation of microbial growth with monthly temperature data from Met Office UK.
- Logistic regression analysis to assess the impact of temperature and season on organism detection.
Main Results:
- Gram-positive bacteria showed increased growth with rising temperatures, while fungi and Moraxella species were associated with decreasing temperatures.
- Overall culture positivity was lower in summer and spring compared to winter.
- Gram-negative bacteria were more prevalent in summer and autumn, whereas Candida and Acanthamoeba species were less common in summer and autumn/spring, respectively.
Conclusions:
- This study demonstrates distinct seasonal and temperature-dependent variations in the incidence of MK-causing organisms in the UK.
- Findings can assist clinicians in predicting potential causative agents of MK based on the time of year.
- Understanding these patterns can inform preventative strategies and treatment approaches for microbial keratitis.
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