Free-living amoebae isolated from a hospital water system in South Africa: a potential source of nosocomial and occupational infection

This study investigated the occurrence of free-living amoebae (FLA) in a public hospital in South Africa. A total of 97 water and biofilm samples 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 were collected and examined for the presence of FLA using an amoebal co-culture and molecular techniques. 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 (polymerase chain reaction) and sequence analyses. Further sequence analysis of the five Acanthamoeba-positive isolates revealed a close resemblance with the potentially pathogenic T20 genotype. 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 harbor 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.