Sally L. Buck

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.

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.