In vitro activity of selected Ghanaian medicinal plants against parasites: Giardia lamblia, Entamoeba histolytica and Naegleria fowleri

Naegleria fowleri causes a deadly disease called primary amoebic meningoencephalitis (PAM). Even though PAM is still considered a rare disease, the number of reported cases worldwide has been increasing each year. Among the factors to be considered for this, awareness about this disease, and also global warming, as these amoebae thrive in warm water bodies, seem to be the key factors. Until present, no fully effective drugs have been developed to treat PAM, and the current options are amphotericin B and miltefosine, which present side effects such as liver and kidney toxicity. Statins are able to inhibit the 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, which is a key enzyme for the synthesis of ergosterol of the cell membrane of these amoebae. Therefore, the in vitro activity of a group of statins was tested in this study against two types of strains of Naegleria fowleri. The obtained results showed that fluvastatin was the most effective statin tested in this study and was able to eliminate these amoebae at concentrations of 0.179 ± 0.078 to 1.682 ± 0.775 µM depending on the tested strain of N. fowleri. Therefore, fluvastatin could be a potential novel therapeutic agent against this emerging pathogen.

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Activities of Azithromycin and Amphotericin B against Naegleria fowleri In Vitro and in a Mouse Model of Primary Amebic Meningoencephalitis

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.47.2.524-528.2003 ◽

2003 ◽

Vol 47 (2) ◽

pp. 524-528 ◽

Cited By ~ 35

Author(s):

Shannon M. Goswick ◽

George M. Brenner

Keyword(s):

Amphotericin B ◽

Vitro Activity ◽

In Vitro Activity ◽

Naegleria Fowleri ◽

Nægleria Fowleri ◽

Free Living Ameba ◽

Primary Amebic Meningoencephalitis ◽

Observation Period

ABSTRACT Inhalation of fresh water containing the free-living ameba Naegleria fowleri may lead to a potentially fatal infection known as primary amebic meningoencephalitis. Amphotericin B is the only agent with established clinical efficacy in the treatment of primary amebic meningoencephalitis in humans, but therapy with this drug is often associated with adverse effects on the kidneys and other organs, and not all persons treated with amphotericin B have survived. We investigated the in vitro activity and in vivo efficacy of newer therapeutic agents in an attempt to identify other useful agents for treating primary amebic meningoencephalitis. Azithromycin has shown in vitro activity against Acanthamoeba spp. and in vivo activity against experimental toxoplasmosis. In our study, the MIC of azithromycin against N. fowleri was 13.4 μM (10 μg/ml), which was 123 times greater than the MIC of amphotericin B, which was 0.108 μM (0.1 μg/ml). Azithromycin protected 100% of mice infected with N. fowleri at a dose of 75 mg/kg/day for 5 days, whereas amphotericin B protected only 50% of mice at a dose of 7.5 mg/kg/day for 5 days, and all control mice died during the 28-day observation period. We conclude that azithromycin has both in vitro and in vivo activity versus N. fowleri and may be a useful addition to therapy for primary amebic meningoencephalitis.

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