Ruth A. Rosenthal

Biocide uptake in contact lenses and loss of fungicidal activity during storage of contact lenses.

Purpose. With recent outbreaks of Fusarium keratitis related to contact lens wear, studies were conducted to determine the biocide uptake during lens storage, and the resulting effect on antifungal activity of related products. Methods. ACUVUE 2 (etafilcon A) soft, hydrophilic contact lenses (group IV) were soaked from 1 hour to 7 days in OPTI-FREE Express and OPTI-FREE RepleniSH multipurpose disinfecting solutions with POLYQUAD (polyquaternium-1) and ALDOX (myristamidopropyl dimethylamine) biocides and multipurpose solutions, Bausch & Lomb ReNu with MoistureLoc (Alexidine), ReNu MultiPlus (polyhexamethylene biguanide [PHMB]), and AMO Complete MoisturePLUS (PHMB). Storage solutions were tested to evaluate the effect of preservative uptake on the residual biocide activity against Fusarium solani. Results. Approximately 30% to 60% of the PHMB and Alexidine were depleted by 6 hours, with comparable loss of antimicrobial activity. Decreasing activity was noted with corresponding decreases in active concentration throughout the course of the evaluation. The POLYQUAD systems retained nearly 100% of the biocide and fungicidal activity and maintained their concentration in the solution. Conclusions. OPTI-FREE Express and OPTI-FREE RepleniSH multipurpose disinfecting solutions maintained fungicidal efficacy after storage of lenses. The Alexidine- and PHMB-based multipurpose solutions tested showed significant uptake of preservative into group IV lenses, resulting in a decrease in the residual activity of the storage solution. The POLYQUAD systems showed a low uptake of biocide and maintained fungicidal efficacy against F. solani.

Anatomy of a regimen: consideration of multipurpose solutions during non-compliant use

Consumers are often non-compliant with instructions for contact lens care products. This study explores the antimicrobial capacity of multipurpose solutions using variable use conditions. Opti-Free Express (Alcon) Multi-Purpose Disinfecting Solution with Polyquad (Alcon) and Aldox (Alcon) antimicrobial system and products containing PHMB (ReNu MultiPlus, Solo-care, and Complete multipurpose solutions) were evaluated. Products were challenged with Fusarium solani, Candida albicans, Serratia marcescens, Pseudomonas aeruginosa, and Staphylococcus aureus. The antimicrobial activity and effectiveness of regimen steps, rinse volume, stored lenses and organic soil were evaluated. The results show that products using similar regimens can show different disinfection abilities. Opti-Free Express Multi-Purpose Disinfecting Solution retained effectiveness using variable and non-compliant conditions.

Amoebicidal activity of a preserved contact lens multipurpose disinfecting solution compared to a disinfectinn/neutralisation peroxide system

The amoebicidal activity of a contact lens multipurpose disinfecting solution (MPDS) containing polyquaternium-1 and myristamidopropyl dimethylamine was compared to a disinfection/neutralisation peroxide system against Acanthamoeba castellanii and Acanthamoeba polyphaga trophozoites and cysts. A quantitative microtitre method was used to evaluate the solutions. The MPDS showed similar amoebicidal activity to the disinfection/neutralisation peroxide system against the trophozoites of both species and equal or more rapid activity against the cysts of both species.

Disinfecting action of a new multi-purpose disinfection solution for contact lenses.

The disinfection activity of a new multipurpose disinfection solution (OPTI-FREE Express with ALDOX) was compared to several other contact lens disinfecting solutions. The new solution is preserved with polyquaternium-1 and myristamidopropyl dimethylamine. The other solutions included 3% hydrogen peroxide systems and multipurpose solutions (MPS) preserved with polyhexamethylene biguanide. The products were tested for antimicrobial activity against Staphylococcus spp., Pseudomonas aeruginosa, Serratia marcescens, Candida albicans, Fusarium solani, and Aspergillus fumigatus. OPTI-FREE Express provided a broader range of antimicrobial activity than the MPS. It provided activity similar to that demonstrated by 3% hydrogen peroxide systems, but unlike the hydrogen peroxide system tested, it also prevented re growth of the organisms during extended storage.

Efficacy of Myristamidopropyl Dimethylamine (Aldox®) Against Corneal Isolates of Acanthamoeba spp.

Amebic keratitis (AK) is a sight-threatening infection caused by the free-living ameba, Acanthamoeba. It can result from corneal trauma but by far the greatest number of cases of AK has been associated with the use of extended-wear soft contact lenses [S]. To date, approximately 3,000 cases have been reported or described in the literature. Among contact lens wearers, a source of infection is the use of ophthalmic saline solutions prepared from non-sterile tap or distilled waters, in which amebae are present either as trophozoites or cysts. Another source is bacterial films that develop in the lens case as a result of poor hygiene, which can provide a food supply for amebae and an opportunity for their attachment to the stored contact lens and, ultimately, the corneal surface. Chlorhexidene gluconate, polyhexamethylene biguanide, and propamidine isethionate used in therapy for AK have greatly improved chances of recovery following infection [7]. However, there are strains of Acanthamoeba isolated from keratitis victims that have shown resistance to these drugs, and there is interest in finding new drugs for controlling infection. We have tested myristamidopropyl dimethylamine (MAPD), present as AldoxB (at a concentration of 5 pg/ml) in Opti-Free Express Disinfecting Solution for contact lens care [51 for its potential as a drug in treatment of Acanthamoeba keratitis. MAPD is an amidoarnine compound that shows activity against Acanthamoeba as well as a variety of other causal agents of microbial keratitis [1,31.