Activities of Therapeutic Agents and Myristamidopropyl Dimethylamine against
            <i>Acanthamoeba</i>
            Isolates

Kilvington, Simon; Hughes, Reanne; Byas, James; Dart, John

doi:10.1128/aac.46.6.2007-2009.2002

Cited by 41 publications

(22 citation statements)

References 15 publications

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“…The method used to determine the kinetics of cyst killing was described previously (9,13). Briefly, 100 l of 2 ϫ 10 6 A. polyphaga (Ros) cysts per ml were inoculated into 10 ml of test or control solution in 50-ml polypropylene centrifuge tubes (Becton Dickinson, Oxford, England).…”

Section: Methodsmentioning

confidence: 99%

“…Incubation with the amino acid taurine and Mg 2ϩ has also been shown to induce encystment (32). The increasing incidence of Acanthamoeba keratitis among contact lens wearers has necessitated the evaluation and development of potential therapeutic agents and contact lens disinfectants active against the resistant cyst stage of the organism (3,5,13,26,33). Disinfection is fundamental to safe contact lens use and, hence, the prevention of infection.…”

mentioning

confidence: 99%

“…Unlike the requirements for bacteria and fungi, no standard protocol exists for testing of the efficacies of disinfectants against Acanthamoeba for use with contact lenses (11). As a consequence, a variety of strains, methods for cyst production, and experimental protocols have been used (1,5,9,10,13,24,31), often with contradictory findings (2,6,8,12,23).…”

mentioning

confidence: 99%

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Acanthamoeba polyphaga Strain Age and Method of Cyst Production Influence the Observed Efficacy of Therapeutic Agents and Contact Lens Disinfectants

Hughes

Heaselgrave

Kilvington

2003

Antimicrob Agents Chemother

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The effects of age in culture and the type of medium used for induction of Acanthamoeba polyphaga (Ros) cysts on susceptibilities to polyhexamethylene biguanide (PHMB; 3 g/ml), chlorhexidine digluconate (30 g/ml), myristamidopropyl dimethylamine (20 g/ml), H 2 O 2 (3%), and two multipurpose contact lens solutions (MPS-1 and MPS-2, based on 1 g of PHMB per ml) were examined. Strain Ros-02 was cryopreserved on isolation in 1991, while strain Ros-91 had been in continuous axenic culture. Significant differences in susceptibilities to the disinfectants were found depending on the medium used for cyst preparation and the age of the test strain, with Ros-02 generally being more resistant. For example, the killing of Ros-91 cysts produced from an axenic culture of trophozoites in the presence of 50 mM MgCl 2 by MPS-2 was 4 logs, but the killing of Ros-02 by MPS-2 was only 2 logs (P < 0.05) and killing of both strains with cysts obtained from monoxenic cultures with Escherichia coli was only 1 log (P < 0.001). Assays repeated with different batches of the various cyst types gave consistent results. A batch of Ros-91 cysts stored at 4°C and tested over an 8-week period with MPS-1 showed progressively increasing susceptibility to disinfection, although there was no loss of viability during storage (P < 0.01). These observations have important implications for the standardization and interpretation of Acanthamoeba disinfectant and therapeutic agent testing.

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Acanthamoeba polyphaga Strain Age and Method of Cyst Production Influence the Observed Efficacy of Therapeutic Agents and Contact Lens Disinfectants

Hughes

Heaselgrave

Kilvington

2003

Antimicrob Agents Chemother

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“…In a series of in vitro studies using corneal organ cultures, Clarke and Niederkorn (2006) demonstrated that Acanthamoeba trophozoites can penetrate the corneal endothelium and the underlying Descemet's membrane, suggesting that the trophozoites can, therefore, enter the anterior chamber. The increasing incidence of Acanthamoeba keratitis among contact lens wearers and other diseases caused by Acanthamoeba has necessitated the evaluation and development of potential contact lens disinfectants and therapeutic agents active against the resistant cyst stage of the organism (Buck et al 1998;Kilvington et al 2002;Borazjani and Kilvington 2005).…”

Section: Discussionmentioning

confidence: 99%

In vitro amoebicidal activity of four Allium species on Acanthamoeba castellanii and their cytotoxic potentials on corneal cells

et al. 2007

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Amoebic keratitis is difficult to treat without total efficacy in some patients because of cysts, which is less susceptible than trophozoites to the usual treatments. We investigated the in vitro effectiveness of the methanolic extract of four Allium species from Turkey against Acanthamoeba castellanii and its cytotoxicity on corneal cells in vitro. Extracts were evaluated for their amoebicidal activities using an inverted light microscope. The effect of the Allium species with concentrations ranging from 1.0 to 32.0 mg/ml on the proliferation of A. castellanii trophozoites and cysts were examined in vitro. For the determination of the cytotoxicity of the Allium species on corneal cells, agar diffusion tests were performed. According to the results obtained from the tests, A. scrodoprosum subsp. rotundum showed remarkable amoebicidal effect on A. castellanii, while the others remained inactive. In the case of cyctotoxic activities, the methanolic extracts of A. scrodoprosum showed no cytotoxicity for the cells in the concentration of 32 mg/ml, while the others exerted significant cytotoxic activities between the concentrations of 1 and 16 mg/ml. As a result, the methanolic extract of A. scrodoprosum could be concluded as a new natural agent against Acanthamoeba. On the other hand, it still needs to be further evaluated by in vivo test systems to confirm the efficiency of its biological effect.

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“…These cysts show high levels of resistance to hydrochloric acid as well as to biocides (15). One remaining cyst can theoretically cause a relapse (41).…”

mentioning

confidence: 99%

Cytotoxic Activity of N -Chlorotaurine on Acanthamoeba spp

Fürnkranz

Nagl

Gottardi

et al. 2008

Antimicrob Agents Chemother

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Acanthamoeba spp. are the causative agents of Acanthamoeba keratitis (AK), which mainly occurs in contact lens wearers, and of skin lesions, granulomatous amoebic encephalitis (GAE), and disseminating diseases in the immunocompromised host. AK therapy is complex and irritating for the eye, skin lesions are difficult to treat, and there is no effective treatment for GAE. Therefore, new anti-Acanthamoeba drugs are needed. We investigated the anti-Acanthamoeba activity of N-chlorotaurine (NCT), an endogenous mild antiseptic. It was shown that NCT has amoebicidal qualities, both in phosphate-buffered saline (PBS) and in amoebic culture medium. After 6 h of treatment with 10 mM NCT in PBS, the levels of trophozoites of all strains investigated already showed at least a 2-log reduction. When the trophozoites were treated with 20 mM NCT in culture medium, they showed a 2-log reduction after 24 h. The addition of NH 4 Cl to NCT led to a faster decrease in the numbers of living cells, if tests were carried out in PBS. A delay of excystation was observed when cysts were treated with 55 mM (1%) NCT in culture medium. A complete failure of excystment was the result of treatment with 1% NCT plus 1% NH 4 Cl in PBS. Altogether, NCT clearly demonstrated amoebicidal activity at concentrations well tolerated by human tissues and might be useful as a topical drug for the treatment of Acanthamoeba infections. The addition of ammonium chloride can be considered to enhance the activity.

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Activities of Therapeutic Agents and Myristamidopropyl Dimethylamine against Acanthamoeba Isolates

Cited by 41 publications

References 15 publications

Acanthamoeba polyphaga Strain Age and Method of Cyst Production Influence the Observed Efficacy of Therapeutic Agents and Contact Lens Disinfectants

Acanthamoeba polyphaga Strain Age and Method of Cyst Production Influence the Observed Efficacy of Therapeutic Agents and Contact Lens Disinfectants

In vitro amoebicidal activity of four Allium species on Acanthamoeba castellanii and their cytotoxic potentials on corneal cells

Cytotoxic Activity of N -Chlorotaurine on Acanthamoeba spp

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