Abstract
Legionella pneumophila can cause a potentially fatal form of humane pneumonia (Legionnaires’ disease), which is most problematic in immunocompromised and in elderly people. Legionella species is present at low concentrations in soil, natural and artificial aquatic systems and is therefore constantly entering man-made water systems. The environment temperature for it’s ideal growth range is between 32 and 42°C, thus hot water pipes represent ideal environment for spread of Legionella. The bacteria are dormant below 20°C and do not survive above 60°C. The primary method used to control the risk from Legionella is therefore water temperature control. There are several other effective treatments to prevent growth of Legionella in water systems, however current disinfection methods can be applied only intermittently thus allowing Legionella to grow in between treatments. Here we present an alternative disinfection method based on antibacterial coatings with Cu-TiO2 nanotubes deposited on preformed surfaces. In the experiment the microbiocidal efficiency of submicron coatings on polystyrene to the bacterium of the genus Legionella pneumophila with a potential use in a water supply system was tested. The treatment thus constantly prevents growth of Legionella pneumophila in presence of water at room temperature. Here we show that 24-hour illumination with low power UVA light source (15 W/m2 UVA illumination) of copper doped TiO2 nanotube coated surfaces is effective in preventing growth of Legionella pneumophila. Microbiocidal effects of Cu-TiO2 nanotube coatings were dependent on the flow of the medium and the intensity of UV-A light. It was determined that tested submicron coatings have microbiocidal effects specially in a non-flow or low-flow conditions, as in higher flow rates, probably to a greater possibility of Legionella pneumophila sedimentation on the coated polystyrene surfaces, meanwhile no significant differences among bacteria reduction was noted regarding to non or low flow of medium.
Highlights
Hospitals, hotels, schools and homes for elderly people are often faced with the contamination of water pipeline systems caused by opportunistic pathogenic microorganisms such as Mycobacterium avium, Pseudomonas aeruginosa and/or Legionella pneumophila (L. pneumophila)
In view of the promising results of previous research, we further examined the effectiveness of nano materials in preventing the colonization of L. pneumophila in some simulated conditions as they arise in drinking water plumbing systems
Energy dispersive X-ray (EDX) analysis showed that the copper content in the material with higher amount of copper (Cu-TiO2 nanotubes (TiO2NTs)) is about 1.2 wt.%, and in the material with lower amount of copper is about 0.1 wt% (S2 Fig)
Summary
Hotels, schools and homes for elderly people are often faced with the contamination of water pipeline systems caused by opportunistic pathogenic microorganisms such as Mycobacterium avium, Pseudomonas aeruginosa and/or Legionella pneumophila (L. pneumophila). Among the pathogenic microorganisms that mostly occur in the water systems bacteria L. pneumophila takes a special place because it can spreads and contaminates the drinking water supply systems and cause a very dangerous Pontiac fever and/or Legionary disease. Considering that this disease can be spread predominantly by the aspiration of an contaminated aerosol, showers, pipes, tubes, cooling towers, thermal springs, water heaters, as well as respiratory devices, or nasogastric tubes in hospitals are predominant places for L. pneumophila contaminations and consequent humane infections [1, 2, 3]. With climate change and increase in precipitation, the incidence of Legionnaire disease is increasing [2]
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