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The In Vitro Efficacy of Antimicrobial Agents Against the Pathogenic Free-Living Amoeba Balamuthia mandrillaris

Authors

  • Arine F. Ahmad,

    1. Department of Infection, Immunity & Inflammation, University of Leicester, Maurice Shock Building, Leicester, United Kingdom
    2. Department of Parasitology, Faculty of Medicine Building, University of Malaya, Kuala Lumpur, Malaysia
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  • Wayne Heaselgrave,

    1. Department of Infection, Immunity & Inflammation, University of Leicester, Maurice Shock Building, Leicester, United Kingdom
    2. Institute of Science and the Environment, University of Worcester, Henwick Grove, Worcester, United Kingdom
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  • Peter W. Andrew,

    1. Department of Infection, Immunity & Inflammation, University of Leicester, Maurice Shock Building, Leicester, United Kingdom
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  • Simon Kilvington

    Corresponding author
    • Department of Infection, Immunity & Inflammation, University of Leicester, Maurice Shock Building, Leicester, United Kingdom
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Correspondence Simon Kilvington, Ph.D., Department of Infection, Immunity & Inflammation, University of Leicester, Maurice Shock Building, University Road, Leicester LE1 9HN, United Kingdom Telephone number: +44 (0)116 252 2942; FAX number: +44 (0)116 252 5030; e-mail: sk46@le.ac.uk

Abstract

The free-living amoeba Balamuthia mandrillaris causes usually fatal encephalitis in humans and animals. Only limited studies have investigated the efficacy of antimicrobial agents against the organism. Assay methods were developed to assess antimicrobial efficacy against both the trophozoite and cyst stage of B. mandrillaris (ATCC 50209). Amphotericin B, ciclopirox olamine, miltefosine, natamycin, paromomycin, pentamidine isethionate, protriptyline, spiramycin, sulconazole and telithromycin had limited activity with amoebacidal levels of > 135–500 μM. However, diminazene aceturate (Berenil®) was amoebacidal at 7.8 μM and 31.3–61.5 μM for trophozoites and cysts, respectively. Assays for antimicrobial testing may improve the prognosis for infection and aid in the development of primary selective culture isolation media.

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