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Bacteria killing rate in vitro after cross-linking

Session Details

Session Title: Cross-linking

Session Date/Time: Monday 07/10/2013 | 14:30-16:30

Paper Time: 15:02

Venue: Elicium 2 (First Floor)

First Author: : F.Hoogewoud SWITZERLAND

Co Author(s): :    O. Richoz   F. Hafezi           

Abstract Details

Purpose:

To demonstrate the antimicrobial efficacy of corneal crosslinking in vitro and to evaluate three different intensities of treatment.

Setting:

Infectious corneal ulceration is a common cause of visual loss. The final outcome is influenced by early diagnosis and traditionally by intensive treatment with topical antibiotics. Today, corneal collagen crosslinking (CXL) represents another therapeutic approach; however, the standard protocol (3 mW/cm2 during 30 min) has not been optimized for this new indication. Our study investigates the effect of CXL on two common pathogenic bacteria, meticillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa, at three different power and time settings.

Methods:

A porous polymer 300 ?m thick, containing 96% of water, not toxic for the bacteria and not UV-absorbing was used as a support for the experiment.  Two solutions of 106 bacteria, one of methicillin-resistant Staphylococcus aureus and one of Pseudomonas aeruginosa, combined with 0.1% Riboflavin solution were instilled in the polymer. Three different protocols of UV-irradiation (365nm) using the same energy (5.4 mJ) at different time and power settings were tested (3 mW/cm2 during 30 min; 9 mW/cm2 during 10 min; 18 mW/cm2 during 5 min). After irradiation, the solution was cultured on a blood agar plate and the CFU (colony forming units) were counted  after 24h of incubation. Controls without riboflavin and with riboflavin but without irradiation were performed.

Results:

At the three different power settings, the number of bacteria was reduced by 2 log(10) scales compared with both control groups. No significant differences were detected between the three protocols.

Conclusions:

CXL is an efficient bacteriosidal method in vitro.  The killing rate of bacteria is equally high with the three protocols tested suggesting that in clinical practice the time-sparing protocol (18 mW/cm2 during 5 min) should provide as good results as the standard protocol (3 mW/cm2 during 30 min). Clinical trials should be conducted to confirm this hypothesis.

Financial Interest:

NONE