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In vitro efficacy of accelerated high-fluence PACK-CXL with Riboflavin for bacterial keratitis

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First Author: F.Gilardoni SWITZERLAND

Co Author(s):    H. Koliwer-Brandl   H. Abdshahzadeh   N. Hafezi   E. Torres-Netto   R. Zbinden   F. Hafezi     

Abstract Details

Purpose:

The interest in ophthalmological treatments that constitute an alternative to antimicrobial agents is rapidly growing. PACK-CXL may represent such an alternative, especially if it could be used at the slit lamp in an accelerated manner. We have recently shown that high-fluence PACK-CXL distinctly increases the bacterial killing ratio. The purpose of this study was to test whether high-fluence PACK-CXL can be accelerated to allow for its use at the slit lamp.

Setting:

The experiments were conducted in the University of Zurich, Switzerland, by the Ocular Cell Biology Group, Center for Applied Biotechnology and Molecular Medicine (CABMM), in collaboration with the Institute of Medical Microbiology of the same institution.

Methods:

Bacterial solutions of 10^7 colony forming units (CFU) per mL of Staphylococcus aureus were prepared with 0.1% riboflavin (Streuli Pharma AG). 11 µl of this solution were irradiated with 15 J/cm2 UV-light at 365 nm. The same fluence was delivered with standard (9 mW/cm2, 27.8 minutes) and accelerated (36 mW/cm2, 6.9 minutes) protocol. Irradiated solutions and controls were diluted, plated and incubated for 24 to 48 hours at 37°C. The number of CFU was counted and the killing ratio was calculated. Additionally, strains of Pseudomonas aeruginosa, Staphylococcus epidermidis, Achromobacter xylosoxidans and Stenotrophomonas maltophila were tested with accelerated PACK-CXL

Results:

The mean fast and slow killing ratios for S.aureus were 75.8% and 95.4%, respectively. In accelerated PACK-CXL, we obtained killing ratios of 75.1% for P. aeruginosa, 58.3% for S. epidermidis, 55.9% for A. xylosoxidans and 49.6% for S. maltophila.

Conclusions:

Although the bacterial killing ratios of high-fluence PACK-CXL are currently lower in accelerated protocols when compared to slow irradiation, they show promising numbers. In a next step, we will optimize the technical settings and use additional enhancers to increase this killing rate.

Financial Disclosure:

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