Acanthamoeba Infection Treatment & Management

Updated: Aug 14, 2017
  • Author: David R Haburchak, MD, FACP; Chief Editor: Pranatharthi Haran Chandrasekar, MBBS, MD  more...
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Treatment

Medical Care

Medical therapy for Acanthamoeba infection is not well established. Early diagnosis and treatment are paramount for improving outcome. Listed below are treatments that have been reported in the literature.

Acanthamoeba keratitis

Successful treatment of keratitis consists of early diagnosis and aggressive surgical and medical therapies. [25, 26]

Medical treatment consists of topical antimicrobial agents, which can achieve high concentrations at the site of the infection.

Because the cyst form may be highly resistant to therapy, a combination of agents is generally used. [19, 27]

Many authorities recommend a combination of chlorohexidine (0.02%) and polyhexamethylene biguanide (PHMB, 0.02%) for treating both the trophozoites and cysts. [26, 27]

These topical antimicrobials are administered every hour immediately after corneal debridement or for the first several days of therapy. These agents are then continued hourly during waking hours for 3 days (at least 9 times/day is recommended) depending on clinical response. The frequency is then reduced to every 3 hours. Two weeks may be required before a response is observed, and the total duration of therapy is a minimum of 3-4 weeks. Some advocate treating for 6-12 months. When therapy is discontinued, close observation is warranted to rule out recurrent disease.

No clear consensus exists about use of steroids. Most authorities recommend that steroid use is probably best avoided but might be used judiciously if anterior-chamber inflammation is present. [19] Patients receiving steroids should continue antiamebic therapy for several weeks after the steroids are stopped.

Acanthamoeba granulomatous amebic encephalitis (GAE)

Treatment is not standardized and is limited. Most use a combination of therapies for the treatment of GAE, which should be urgently administered. 

Early therapy with a multidrug regimen is the best approach. If possible, immunosuppression should be reversed. A combination of pentamidine, an azole (fluconazole or itraconazole), a sulfadiazine, and flucytosine can be considered.

In vitro and in vivo data suggest that the following medications have activity against Acanthamoeba:

  • Ketoconazole, miconazole, itraconazole, fluconazole, voriconazole
  • Miltefosine (available from the CDC) [28]
  • Pentamidine
  • Amphotericin B (to a lesser extent)
  • Paromomycin
  • Polymyxin
  • Trimethoprim-sulfamethoxazole
  • Sulfadiazine
  • Flucytosine
  • Clotrimazole
  • Rifampin

Other potential regimens have included several combinations of the above agents.

Two immunocompetent children survived with treatment that consisted of ketoconazole, rifampin, and trimethoprim-sulfamethoxazole. A recent case reported discussed the use of this combination, but the patient ultimately relapsed and died of progressive leukemia. [29] . A heart transplant recipient was successfully treated with a combination of flucytosine, fluconazole, miltefosine, and decreased immunosuppression. [30]

Other potential regimens include (1) fluconazole and sulfadiazine or (2) pentamidine, amphotericin, flucytosine, rifampin, itraconazole, and chlorhexidine.

Disseminated Acanthamoeba disease

A case that involved only the skin was treated with intravenous pentamidine, topical chlorhexidine gluconate, and 2% ketoconazole cream, followed by oral itraconazole.

New and emerging therapies for Acanthamoeba infection

Because of the severity of these infections and the difficulty in killing both cysts and trophozoites without cellular toxicity, a wide range of new therapies are being evaluated in animals and humans. [31] These include both new and old technologies, as well as drugs with new delivery systems, such as liposomes, and new mechanism of action, such as small inhibitory RNA molecules [32] and agents designed to activate programmed death pathways. [33]

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Surgical Care

Acanthamoeba keratitis: The abnormal epithelium is débrided. Penetrating keratoplasty/corneal transplantation may be necessary in cases that do not respond to medical therapy. [34, 19]

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Consultations

See the list below:

  • Keratitis

    • Infectious diseases specialist

    • Ophthalmologist

  • Granulomatous amebic encephalitis and disseminated disease

    • Infectious diseases specialist

    • Neurologist

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Prevention

Acanthamoeba keratitis may be prevented by scrupulous and appropriate use of contact lenses.

Although unproven, nasal irrigation with unsterile water is probably inappropriate for severely immunocompromised hosts.

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Long-Term Monitoring

Because of the chronicity of Acanthamoeba diseases, they require long-term monitoring for relapse.

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