Author: Muchesa P, Leifels M, Jurzik L, Barnard TG, Bartie C

Source: Water Science & Technology 2015


Introduction: Free-living amoebae (FLA) are unicellular eukaryotes that are ubiquitous in the environment, mainly in natural aquatic environments (rivers, streams, hot springs) as well as in man-made water systems such as domestic tap water, swimming pools and hospital water distribution networks. Although mostly beneficial in their natural habitat, some FLA are transmitters of pathogenic bacteria and are known human pathogens that can cause opportunistic and non-opportunistic central nervous system infections, as well as lung and skin infections. The aim of this study is to find out if patients and healthcare workers may be exposed to potentially pathogenic FLA in hospital water distribution.

Objectives: To investigate the occurrence of FLA and potential intracellular bacteria in a public hospital in South Africa.

Methods: A total of 97 water and biofilm samples were collected from the municipal water inlet of the hospital, theatres, theatre sterilization service unit, central sterilization service unit, endoscopy/gastroscopy unit, intensive care unit and the renal unit.These were analysed for the presence of FLA using amoebal enrichment technique, PCR and sequencing.

Results: Of the 97 samples, 77 (79.4 %), 40 (52%) water and 37 (48.1%) biofilm, contained FLA. The genera Acanthamoeba, Vermamoeba (formerly Hartmanella) and Naegleria were detected by morphology, 18S rRNA PCR and sequence analyses. Further sequence analysis of the Acanthamoeba positive isolates revealed a close resemblance with the potentially pathogenic T20 genotype. Transmission electron microscopy of positive FLA samples showed the occurrence of potential intracellular bacteria whose identity were not determined in this study

Discussion: These results show a potential health risk to immuno-compromised patients and health care workers as some of the species detected are pathogenic and may harbour potential intracellular bacteria responsible for nosocomial infections. To date, this is the first report on the detection of potentially pathogenic amoebae from South African hospital water systems.