Free-living Amoebae are unicellular protozoan’s common in aquatic
ecosystems, which are also known to colonize Human created water systems such
as water supply systems and swimming pools. Whilst in some ways these organisms
can be helpful, consuming a range of Bacterial, Viral and Fungal pathogens, they
have also been shown to cause a range of infections themselves, and can
themselves be infected by a variety of pathogenic Bacteria, such as Legionella pneumophila, Mycobacteria, Pseudomonas aerugionosa and Acinetobacter
baumannii. Whilst most Bacteria are consumed and digested by the Amoebae,
these pathogenic species have been shown to be able to resist digestion,
instead surviving within the Amoebae, where they receive protection from
biocides and antibiotics, later emerging to cause infections in Humans.
In a paper published in the South African Journal of Science in
January 2015, Petros Muchesa and Tobias Barnard of the Water and HealthResearch Centre at the Department of Biomedical Technology at the University of Johannesburg and Catheleen Bartie of Immunology and Microbiology at the
National Institute for Occupational Health, describe the results of a series of
tests in which water samples and swab samples from taps and showers were
collected from a number of locations at a hospital in Johannesburg and cultured
to determine the presence of free-living Amoebae.
Muchesa et al. were able
to culture Amoebae belonging to three identified genera, Acanthamoeba, Hartmanella
and Balamuthia, as well as a number
of unidentified species, from 43.7% of the water samples and 45.1% of the swab
samples.
Balamuthia cysts (indicated by arrows) in water and biofilm samples from
ahospital water system. Muchesa et al. (2015).
There have been relatively few published studies on free-living
Amoebae in hospital water supplies, but these results are higher than a study
of water in a Swiss hospital in 2006 which found Amoebae in 5.7% of samples and
a study from American hspitals in 2014, which found Amoebae in 14.8% of samples.
While there have not been any reported instances of Amoeba-related
invfections at the hospital, Acanthamoeba
and Balamuthia have previously been
implicated in infections of the eyes, skin and nervous system, and the presence
of these organisms in the water supply system is of concern, particularly as
the hospital has a high proportion of immunocompromised patients.
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