Abstract
D.Tech. (Biomedical Technology)
Contamination of hospital water systems with bacteria, viruses, fungi and protozoa is a potential risk for nosocomial infections to patients and medical personnel. Among these microorganisms, protozoa such as free-living amoebae (FLA) exist in high numbers in the natural aquatic environment where they play a useful role as predators of microorganisms. Free-living amoebae have also been isolated from man-made water systems such as cooling towers, hospital water networks and wastewater and drinking water plants. Although most FLA are non-pathogenic, some species including Naegleria fowleri, Balamuthia mandrillaris, Acanthamoeba species are known human pathogens and also harbour and transmit bacterial pathogens in the environment. These bacteria referred to as amoeba resistant bacteria (ARB) include nosocomial pathogens such as methicillin-resistant Staphylococcus aureus, Pseudomonas species, Legionella pneumophila and environmental Mycobacterium species. Other non-pathogenic FLA such as Vermamoeba vermiformis, are also known carriers of pathogenic ARB. The importance of drinking water quality distributed through public health care facilities in Johannesburg, with special reference to FLA and certain ARB, has not been studied previously.
Therefore, the aim of this study was to investigate the occurrence of potentially pathogenic FLA and their associated bacteria in three selected public hospital water networks in Johannesburg. This was an observational, descriptive study of the three water distribution systems. Walk-through assessments were conducted for the three water systems to determine areas of high risk for infection by waterborne pathogens and history of waterborne diseases in those areas. A sampling strategy was then established. A total of 275 water (143) and swab (132) samples were collected from the inlets, theatres, intensive care units, endoscopy units, renal units, neonatal ward, milk room, diarrhoea ward and sterilization units. The water physico-chemical elements: pH, temperature, residual chlorine and total dissolved solids were determined at the site of collection. The water samples were also tested for the presence of microbial indicators using the micro-most probable number (MPN) method. All the samples were filtered and analyzed using an amoebal enrichment technique. Observed autochthonous amoebae were then purified and examined for the presence of FLA and intracellular bacteria transmission electron microscopy,..