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Heather Ann Durkee, Nidhi Relhan, Alejandro Arboleda, Mariela C Aguilar, Karam AlRahman Alawa, Francisco Halili, Cornelis Rowaan, Guillermo Amescua, Harry W Flynn, Darlene Miller, Jean-Marie A Parel; Rose bengal-mediated photodynamic antimicrobial therapy to inhibit Pseudomonas aeruginosa isolates in agar plates and contaminated contact lens cases. Invest. Ophthalmol. Vis. Sci. 2016;57(12):No Pagination Specified.
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© ARVO (1962-2015); The Authors (2016-present)
Pseudomonas aeruginosa is often present in contact lens cases and can adhere to the contact lens and cause keratitis in patients. Keratitis secondary to Pseudomonas aeruginosa is difficult to treat medically and, in severe cases, can cause corneal ulceration and perforation. In this study we evaluate an alternative antimicrobial treatment, rose bengal-mediated photodynamic antimicrobial therapy (PDAT), for the inhibition of Pseudomonas aeruginosa on agar plates and in patients’ contaminated contact lens cases.
Pseudomonas aeruginosa isolates were prepared into inoculum of concentration 104 cfu/mL. Isolates were mixed with one of three concentrations of rose bengal (0.1%, 0.05% & 0.01%) or water (control) and plated onto agar plates. Plates were kept in the dark or underwent irradiation with a custom-built green LED light source for a total energy density of 5.4 J/cm2. At 72 hours, agar plates were photographed and growth was measured with LabVIEW software.Contaminated contact lens cases were collected from six patients with suspected contact lens-induced keratitis of mixed microbial communities. Cases were rehydrated with balanced salt solution for 24 hours and cultured onto sheep’s blood agar. Rose bengal-mediated PDAT was performed on contact lens cases, as above. The cases were then decanted, 2 mL of tryptic soy broth was added, and cases were cultured again. Photographs of agar plates were taken for analysis.
PDAT using all concentrations of rose bengal was able to inhibit Pseudomonas aeruginosa growth within central 47mm diameter, corresponding to the irradiation source diameter, and extended outwards towards the edge of the plate. Rose bengal without irradiation showed no inhibition. Contact lens case experiments showed no difference in growth between pre- and post-PDAT cultures.
Pseudomonas aeruginosa can be inhibited by rose bengal-mediated PDAT with 0.1%, 0.05%, and 0.01% concentrations on agar plates. In the contact lens cases, PDAT could not inhibit Pseudomonas aeruginosa, likely because the rose bengal could not penetrate the biofilm present. Further studies are needed to understand microbial biofilm properties and how this influences PDAT and other treatments.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
Rose bengal-mediated PDAT of Pseudomonas aeruginosa compared to controls on agar plates.
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