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MICROBIAL KERATITIS

Microbial Keratitis

Facts and figures

Treatments

Antibioitc resistance

UV-C treatment

extras

Videos and research papers

General Treatment PrinciplesPrompt Diagnosis: Early and accurate identification of the causative microorganism is crucial. This often involves corneal scrapings or cultures to determine the pathogen. Empirical Therapy: Initial treatment is often empirical, based on the most likely causative organisms, before specific pathogen identification. Close Monitoring: Frequent follow-up is necessary to monitor the response to treatment and make adjustments as needed.

Specific Treatments

Bacterial Keratitis

• Broad-Spectrum Antibiotics: Empirical treatment typically starts with broad-spectrum topical antibiotics. Commonly used antibiotics include: Fluoroquinolones: Such as moxifloxacin or ciprofloxacin.

• Combination Therapy: Combining a cephalosporin (e.g., cefazolin) and an aminoglycoside (e.g., tobramycin) for severe cases.

• Systemic Antibiotics: Oral or intravenous antibiotics may be necessary for severe infections or if the infection has spread beyond the cornea.
• Steroids: Topical corticosteroids might be added after initial antibiotic treatment to reduce inflammation.

• 5% global blindness is due to MK

USA: USA there are >1 million health care interactions per year with direct costs in the region >$245 million.

UK:MK is the most common (non-surgical) ophthalmic emergency admission. ~35,000 cases per year. It is the most common non-surgical ophthalmic emergency admission. In UK, fungal keratitis patients: 80% require in-patient care for on average 18.9 days (a hospital stay >4.8 days is loss making for NHS). 50% of fungal keratitis cases are surgical (require transplant). Total costs to NHS in England have been modelled at £2.8m.

India: 1.5 - 2 million cases p.a. (50% bacterial, 50% fungal). Low daily wages in affected population, high associated costs. Loss of vision >60% of cases. Corneal transplant required >15% of cases.

UV light ranges in wavelength from 100 to 400 nm and is subdivided into UVA, UVB and UVC to describe long (>315 nm), middle (280–315 nm) and short (<280 nm) wavelengths, respectively. Ultraviolet C (UVC) light has natural antimicrobial activity due to its efficient absorption by microbial nucleic acids leading to bacterial cell death.

UVC has been used in high doses as an antimicrobial agent across a wide range of applications, and has been demonstrated to inactivate bacteria that cause keratitis. Therefore, it is possible that UVC may be effective in treating infectious keratitis.

Our project aims to determine whether UVC light will inactivate the ESKAPE bacteria, and the 5 WHO priority fungal pathogens, growing on a surface of the eye for microbial keratitis while leaving the other corneal cells undamaged. We will be using porcine eye models for our work.

Research papers

The role of fungi in fungal keratitis

Click on the video link to watch see how Corneal Ulcers effects a patient. A video created by Aravind Eye Care Systems, our collaborators in India.

Rapid Point-of-Care Identification of Aspergillus Species in Microbial Keratitis

Follow Dr Beth Mills on twitter to keep up to date on our research on Microbial Keratitis.

Photosensitizer-Amplified Antimicrobial Materials for Broad-Spectrum Ablation of Resistant Pathogens in Ocular Infections

A Frugal Point-of-Care System for Fluorescent Detection of Bacteria From a Pre-Clinical Model of Microbial Keratitis

Antimicrobial resistance (AMR) is an characteristic encoded by genes in microbes. It is a global issue that has made some bacterial infections challenging to treat. The World Health Organisation (WHO) states that AMR is one of the top global public health and development threats. It is estimated that bacterial AMR was directly responsible for 1.27 million global deaths in 2019 and contributed to 4.95 million deaths.

• Increased bacterial antimicrobial resistance to fluoroquinolones, beta-lactams and aminoglycosides reported in isolates from MK patients.

• Fungal antimicrobial resistance in MK: limited data available.
• Azole resistance increasing in Aspergillus fungi (agricultural use).
• New treatment options are required for both bacterial and fungal keratitis

Microbial keratitis (MK) is a sight-threatening infection of the cornea, and a leading cause of blindness. There are several different classes of pathogen that can cause MK, but in the UK, infections are initially presumed bacterial, and antibiotics are prescribed. Unfortunately, these infections may also be caused by fungi (5-9% of cases), and antibiotics won’t help these infections. Therefore, the infection is able to progress, which makes it harder to treat and leads to complications and vision loss. As fungal infections are already more difficult to treat, this is doubly problematic.

Numerous microorganisms have been implicated in MK, either as single invading pathogens or in polymicrobial infections, predominantly of bacterial origin but the infection is often fungal too.