Molecular confirmation of Sappinia pedata as a causative agent of amoebic encephalitis

Area of Science:

• Microbiology
• Infectious Diseases
• Neuroscience

Background:

• Pathogenic free-living amoebae (FLA) such as Acanthamoeba, Balamuthia mandrillaris, and Naegleria fowleri are known causes of central nervous system infections in humans and animals.
• Historically, Sappinia species were not considered significant human pathogens.

Observation:

• A 2001 case of human encephalitis presented with amoebic morphology suggestive of Sappinia.
• The etiological agent, initially identified as Sappinia diploidea, was re-identified using novel real-time PCR assays.
• This amoeba was confirmed as Sappinia pedata, an organism previously documented only in environmental niches like soil and tree bark.

Findings:

• Real-time PCR assays enabled accurate identification of the Sappinia species involved in the human encephalitis case.
• Morphological and molecular data confirmed the etiological agent as Sappinia pedata, not S. diploidea.
• This represents the first documented human infection caused by Sappinia pedata.

Implications:

• The findings demonstrate that Sappinia pedata, an environmental amoeba, can cause severe human infections like encephalitis.
• This expands the list of free-living amoebae with pathogenic potential for humans.
• Further research into environmental amoebae is warranted to identify potential emerging pathogens and understand transmission routes.