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Marina Nikolic, Simon Kilvington, Nancy Brady, Anthony Lam, Simon Cheung; Comparative Efficacy Of New Contact Lens Care Solutions Against Bacteria, Fungi And Acanthamoeba. Invest. Ophthalmol. Vis. Sci. 2011;52(14):5837.
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Keratitis occurs with greater frequently in contact lens wearers. The microbiological efficacy of multi-purpose solutions (MPS’s) has been subject to scrutiny following two product recalls due to keratitis outbreaks with the mould Fusarium and the amoeba Acanthamoeba. In this study the biocidal efficacy of two new commercial MPS’s were compared to an establish formulation and a 1-step hydrogen peroxide system.
Test solutions were: new MPS’s containing the biocidal agents PQ-1 with PHMB (MPS-1) and PQ-1 with alexidine (MPS-2), PQ-1 with MAPD (MPS-3) and a 1-step hydrogen peroxide system with a platinum neutralizing disc system (Per-1). Test organisms were: Pseudomonas aeruginosa (ATCC 9027), Serratia marcescens (ATCC 13880), Staphylococcus aureus (ATCC 6538), Candida albicans (ATCC 10231), Fusarium solani (ATCC 36031) and A. castellanii (ATCC 50370). Biocidal assays were performed according to ISO 14729. Acanthamoeba trophozoite and cyst viability was determined by a most probable number approach. Loss of Fusarium biocidal efficacy following partial evaporation of the MPS’s was also studied.
Both MPS-1, MPS-2 and Per-1 gave similar results with a 4-5 log kill of the bacteria and a 3-4 log kill of fungi after 4-6 hr exposure. MPS-3 showed reduced efficacy against S. aureus, S. marcescens and F. solani with log reductions of 2.3, 2.8 and 2.1, respectively, after 6 hr. A. castellanii trophozoite log kills at 6 hours were >3.0 for MPS-1, MPS-2 and Per-1, and 2.4 for MPS-3. For the cysts, MPS-1 and MPS-3 showed only a 0.2-0.5 log kill at 6 hours and 2.2 log with Per-1 compared to >3.0 Log by 4 hr with MPS-2. In the evaporation studies, MPS-3 was found to lose 70-85% of Fusarium efficacy when evaporated to 2x and 4x concentration. MPS-2 was also shown to give >4 log kill of clinical isolates of bacteria and fungi, including S. aureus MRSA, S. maltophilia, Enterococcus sp. and Candida sp.
Both the new MPS’s studied here showed good antimicrobial efficacy although MPS-2 had significantly greater activity against A. castellanii cysts. Recent product recalls have highlighted the importance of both MPS design and microbiological testing methods to meet the challenge of emerging pathogens, user noncompliance and newer, more complex, product formulations.
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