WATER HYGIENE AND SAFETY
Antibacterial efficacyofsilver in hoses proven in study
Joachim Otto Habel, a Filtration Project manager at Johs. Tandrup A/S, discusses a laboratory study undertaken by Professor Anthony Hilton of Aston University in the UK, where Tandrup’s T-Safe antibacterial hoses incorporating a silver-based bacteriostatic additive were shown to significantly outperform additive- free control hoses in reducing mean aerobic bacterial counts of Pseudomonas aeruginosa after 8-12 weeks. The company believes the T-Safe hoses could thus offer significant infection reduction benefits and added protection for immunosuppressed patients in hospitals and other healthcare facilities.
Plumbing systems have been implicated as one of the major main routes of infections in hospitals, nursing homes, and private households. In hospitals, 5.1-11.6% of all infections are mainly water- related. The most commonly found bacteria in plumbing systems, so-called ‘opportunistic premise plumbing pathogens’ (OPPPs), Legionella pneumophila (L. pneumophila), Mycobacterium avium (M. avium), and Pseudomonas aeruginosa (P. aeruginosa), cause approximately 30,000 diseases per year in the USA alone, at a cost of approximately US $850 million.1 Disinfection treatment in the form of thermal disinfection, chlorine, chlorine dioxide, ozone, or copper-silver ionisation, can reduce bacteria levels, but cannot sufficiently eliminate biofilm.2
Users of
healthcare facilities are principally exposed to water, and thus potentially to waterborne pathogens, via taps and showers.
Stagnating water in shower hoses – a potentially overlooked threat While in most hospitals, taps are commonly fitted with a point-of-use-filter, the use of point-of-use-shower heads is significantly less frequent, despite their availability. This is probably due to the assumption that shower water is not considered for consumption. There is however, a risk of consumption, and, equally, inhalation of aerosols, from showers that can contain L. pneumophila bacteria, which can cause Legionellosis – the collective name given to pneumonia- like illnesses caused by Legionella bacteria, including the most serious, Legionnaires’ disease.1
Additionally,
showers are mainly exposed to mixed water, and long stagnation intervals, as well as shower hoses made of flexible polymeric materials, which leach biofilm- enhancing organic carbon at significantly higher levels than piping material.2
From
this perspective, shower hoses pose a significant threat to immunosuppressed
54 Health Estate Journal July 2020 Figure 1: A test rig for shower hose operation.
shower users in hospitals, nursing homes, and private households. In a study involving 78 shower hoses from around the world, parameters including use of disinfectant, quality of materials, the age of the shower hose, usage patterns, and water type, were examined to identify the key factors in biofilm formation. The study concluded that lack of disinfectant use,
installation of new showers, poor-quality material, and irregular use of the showers, were all factors that contributed to increased biofilm formation.2
Silver-based bacteriostatic additives One potential solution is to incorporate bacteriostatic additives into shower hoses to reduce biofilm formation. Silver
Abstract
Standing water in shower hoses poses a microbiological threat to immunocompromised patients in hospitals, care homes, and other healthcare facilities. Silver-based bacteriostatic additives, integrated in the hose material, can significantly reduce biofilm formation. A laboratory study conducted by Professor Anthony Hilton of Aston University compared T-Safe Antibacterial Hoses containing a silver-based bacteriostatic additive with additive-free control hoses exposed to standing mixed water for 12 weeks in terms of bacterial growth, including of Pseudomonas aeruginosa (P. aeruginosa). While the control hoses showed a bacterial colonisation of over 350,000 cfu/mL with all microorganisms, and of 40,000 cfu/mL for P. aeruginosa, the T-Safe Antibacterial Hose reduced the mean aerobic bacterial count by 93-99% over a five-week period, and by 88.5-91% from week 8 to 12, compared with the control hoses; P. aeruginosa counts were down by 95.5% for week 8, and by 53% for week 12. Thus, antimicrobial hoses incorporating a silver-based bacteriostatic additive show promise in reducing the risk of microbiological contamination and infection from pathogenic bacteria.
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