Drastic Measures for Drastic Infections

Amebae fighting investigational medication made available from CDC to counter deadly infections

(RxWiki News) Free-living amebae (FLA) are tiny creatures that can cause rare but serious infections in humans. Now officials are allowing the use of an experimental medication in an attempt to quickly manage difficult-to-treat FLA infections.

Infections from these single-celled living organisms often end in death, leading the Centers for Disease Control and Prevention (CDC) to announce a new policy aimed at treating these infections. 

The CDC announced it is working with the US Food and Drug Administration (FDA) to make an investigational new medication available to patients coping with FLA infections. 

"Wash your hands carefully before touching your eyes or contact lenses."

According to the CDC, one infection-causing FLA is Naegleria fowlerisometimes called the "brain-eating amoeba". Naegleria fowleri is usually spread when contaminated freshwater enters the body through the nose (like when swimming in a lake or river). It can cause a rare but fatal brain infection called primary amebic meningoencephalitis (PAM).

Another FLA, Balamuthia mandrillaris, is thought to cause infections in humans when contaminated soil is breathed in or enters the body through cuts on the skin. This FLA can cause granulomatous amebic encephalitis (GAE), an infection of the spinal cord and brain that is another rare but fatal disease.

Acanthamoeba is another FLA that can infect the eyes, skin and central nervous system after being spread through cuts on the skin, inhalation or contact lens use. This FLA is found worldwide in water and soil. According to the CDC, most people will be exposed to Acanthamoeba at some point, but very few will become ill from it.

When Acanthamoeba does cause serious sickness, it can lead to acanthamoeba keratitis, an eye infection that can cause blindness, GAE and widespread infection of the sinuses, lungs, skin and/or other organs. 

In an article written by Jennifer R. Cope, MD, MPH, of the CDC's National Center for Emerging and Zoonotic Infectious Diseases, the reasoning behind the new CDC policy was explained. 

Although test tube experiments have shown that some medications have the potential to fight FLA, the death rate from FLA infections still remains greater than 90 percent when using combinations of medications as treatment, Dr. Cope reported.

The CDC is taking steps to provide a new option in cases of these rare but serious infections.

According to Dr. Cope, an investigational medication called miltefosine has shown potential against FLA in test tube experiments, but is not readily available in the US due to its investigational status. This medication was created as a treatment for leishmaniasis, a parasitic infection spread by sandflies. 

"With CDC assistance, however, miltefosine has been administered since 2009 for FLA infections as single-patient emergency use with permission from the Food and Drug Administration (FDA)," wrote Dr. Cope.

"The drug has been used in a limited number of B. mandrillaris and Acanthamoeba infections, and though the samples are small, their results hint that treatments containing miltefosine can offer patients a "survival advantage," said Dr. Cope. 

Because of this past success, the CDC has created a protocol — called an "expanded access investigational new drug protocol" — in conjunction with the FDA to allow miltefosine to be available directly from the CDC to treat FLA within the US. 

According to Dr. Cope, this expanded access to miltefosine is supported by 26 case reports of FLA infection that included miltefosine in the treatment. The medication is generally well-tolerated by patients and the most commonly seen side effects tend to be gastrointestinal issues. 

"Clinicians who suspect they have a patient with FLA infection who could benefit from treatment with miltefosine should contact CDC to consult with an FLA expert," noted Dr. Cope. 

As officials closely watch the use of miltefosine under these new expanded policies, they will learn how the investigational medication treats FLA in these life-threatening circumstances.

The article by Dr. Cope was published August 23 in the CDC's Morbidity and Mortality Weekly Report (MMWR). No conflicts of interest were reported. 

Review Date: 
August 22, 2013