Susceptibility of various corneal fungal isolates and Pseudomonas aeruginosa to contact lens disinfecting solutions.

INTRODUCTION We aimed to investigate the susceptibility of a combined inoculum of Pseudomonas aeruginosa and different fungal strains to 6 soft contact lens disinfectants. METHODOLOGY One corneal isolate of P. aeruginosa and 13 corneal fungal isolates (9 Aspergillus spp, 3 Fusarium spp, 1 Curvularia sp.) were used. The following solutions were tested: Arion Cronos, Complete RevitaLens, Dua Elite, Opti-Free Express, Regard, Oxysept Comfort, and Oxysept Comfort without catalase. The effect of the solutions was assessed on a combined inoculum of P. aeruginosa plus 1 fungal strain. Suspensions of P. aeruginosa and fungi were made in the solutions (1x106 colony-forming units/mL). After 1 hour (Arion Cronos only), 6, 8, and 24 hours, aliquots of suspension were removed and seeded on Luria-Bertani and Sabouraud agar plates. RESULTS After 6 hours' exposure, all the solutions but Dua Elite and Oxysept Comfort eradicated P. aeruginosa. Conversely, apart from 3% hydrogen peroxide-based Oxysept Comfort without catalase, which eradicated all the fungi tested after 6 hours, all the other solutions were partly ineffective at killing some of the fungal isolates, even after 24 hours' exposure. CONCLUSIONS Most contact lens disinfectants may be ineffective if contact lens care systems become co-contaminated with P. aeruginosa and fungi. In our experiment, only exposure to 3% hydrogen peroxide without neutralizer for at least 6 hours was always able to kill a combined inoculum of P. aeruginosa and different fungal strains.