antibiotics go unrecognised. He added that as many as 40 per cent of Pseudomonas infections in intensive care units may be acquired from water systems. So how does the organism get into water? Like Legionella, Pseudomonas can enter in small numbers in mains waters and then form biofilm in conducive conditions, such as stagnant water in system dead legs. ‘Retrograde’ contamination, where the organism is transmitted back to a tap from an infected individual, has been also been well- documented. This may be caused when sinks are used for inappropriate disposal of patient secretions and are poorly cleaned, which transfers the organism to the outlet. Eighty to 90 per cent of Pseudomonas contamination occurs in the periphery of water systems, which can be harder to eradicate than contamination of main systems. Pseudomonas also favours limescale deposits and trapped debris in flow straighteners and aerators in tap Environmental Health News • May 2013 • 29 Resources A missed epidemic Water samples can only ever provide a snapshot in time I t was only in January last year that Pseudomonas — specifically P. aeruginosa — was flagged up in earnest as being transmitted by water. Three babies in a Belfast neonatal unit died from infections traced back to contaminated taps and the resulting media attention led to pressure on regulatory bodies to work out what lessons needed to be learned. Superseding the Department of Health’s interim advice following the Belfast incident, new guidance has been issued on controlling and minimising the risks from P. aeruginosa associated with water outlets. The document is an addendum to Health Technical Memorandum 04-01 on the control of Legionella in water systems. It addresses how to assess risk, water sampling, testing and monitoring, remedial actions, and development of water safety plans. Although aimed mainly at augmented care units, the addendum’s recommendations also have implications for health and safety in care facilities, where there may be residents with compromised immune systems. This might be as a result of treatments such as chemotherapy or due to other pre-disposing factors for Pseudomonas infection, such as chronic wounds or points of entry for catheters or ventilation tubes. Like Legionella bacteria, P. aeruginosa bacteria inhabit moist environments because they can form a ‘biofilm’ that attaches to inanimate surfaces. While the organism is only problematic for those with weakened immune systems, the dangers to those affected are constantly increasing as the organism has become highly resistant to many antibiotics. At a meeting sponsored by Pall Medical, Dr Mike Weinbren, director of infection prevention and control at University Hospitals Coventry and Warwickshire, said Pseudomonas infections associated with water are not new: there are reports of outbreaks from before 2000. Dr Weinbren said that there may be a ‘missed epidemic’: the literature is dominated by infections caused by resistant strains, so many other instances of waterborne Pseudomonas infections that are sensitive to outlets. Both Pseudomonas and Legionella have been found inside the complex mechanisms of infra-red operated taps. Thermostatic mixer valves and EPDM (synthetic rubber) hoses, which use materials susceptible to biofilm formation, can also be problematic. Also speaking at the meeting, microbiology consultant and former directorate manager of the Department of Medical Microbiology at Royal Liverpool and Broadgreen University Hospitals Dr Tom Makin noted that many of the control mechanisms for Pseudomonas are similar to those for Legionella. A voidance of build-up of biofilm is crucial, he said, with regular flushing of outlets the key to preventing stagnation. He also stressed that: ‘You cannot be certain that outlets are completely clear of Pseudomonas and Legionella just by doing risk assessments and testing. Water samples can only ever provide a snapshot in time. This is because sampling will only pick up free-floating forms, so sampling must take place when the outlet has been least used.’ Other control measures include avoidance of aerators, flow straighteners, overly-complex infra red outlets, TMVs and flexible hoses. Patient secretions should not be put down sinks, Dr Makin said, and cleaning staff should be trained on the correct cleaning procedures for taps and sinks. In most situations the only way of being absolutely sure that water is free of bacteria is to install point-of-use (POU) filtration incorporating 0.2μm membranes. This is confirmed in the new guidance, which recommends POU filters on outlets as an option in this context and as a possible solution in the event of contamination. E The Dublin Masterclass, chaired by Hilary Humphreys, professor of clinical microbiology and consultant microbiologist at Beaumont Hospital, Dublin, was one of an ongoing series of free educational seminars on water quality and the prevention and control of waterborne pathogens. www.specialistmasterclasses.com/ home.html Susan Pearson BSc is a freelance journalist specialising in medicine and the environment. Waterborne Pseudomonas bacteria are a common source of infection in care settings. Susan Pearson reports Cut it out: waterborne Pseudomanas bacteria can be blocked by installing water filters p29 EHN04_Feature_v2.indd 29 24/04/2013 12:20
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antibiotics go unrecognised. He added that as many as 40 per cent of Pseudomonas
infections in intensive care units may be acquired from water systems.
So how does the organism get into water? Like
Legionella, Pseudomonas can enter in small numbers in mains waters and then form biofilm in conducive conditions,
such as stagnant water in system dead legs.
‘Retrograde’ contamination, where the organism is
transmitted back to a tap from an infected individual, has been also been well-documented. This may be caused when sinks are used for inappropriate disposal of patient secretions and are poorly cleaned, which transfers the organism to the outlet.
Eighty to 90 per cent of Pseudomonas contamination occurs in the periphery of water systems, which can be harder to eradicate than contamination of main systems. Pseudomonas also favours limescale deposits and trapped debris in flow straighteners and aerators in tap
Environmental Health News • May 2013 • 29
Resources
A missed epidemic
Water samples can only ever provide a snapshot in time
It was only in January last year that Pseudomonas — specifically P. aeruginosa — was flagged up in earnest as being transmitted by water. Three babies in a Belfast neonatal unit died from infections traced back to contaminated
taps and the resulting media attention led to pressure on regulatory bodies to work out what lessons needed to be learned.
Superseding the Department of Health’s interim advice following the Belfast incident, new guidance has been issued on controlling and minimising the risks from P. aeruginosa associated with water outlets. The document is an addendum to Health Technical Memorandum 04-01 on the control of Legionella in water systems. It addresses how to assess risk, water sampling, testing and monitoring, remedial actions, and development of water safety plans.
Although aimed mainly at augmented care units, the addendum’s recommendations also have implications for health and safety in care facilities, where there may be residents with compromised immune systems. This might be as a result of treatments such as chemotherapy or due to other pre-disposing factors for Pseudomonas infection, such as chronic wounds or points of entry for catheters or ventilation tubes.
Like Legionella bacteria, P. aeruginosa bacteria inhabit moist environments because they can form a ‘biofilm’ that attaches to inanimate surfaces. While the organism is only problematic for those with weakened immune systems, the dangers to those affected are constantly increasing as the organism has become highly resistant to many antibiotics.
At a meeting sponsored by Pall Medical, Dr Mike Weinbren, director of infection prevention and control at University Hospitals Coventry and Warwickshire, said Pseudomonas infections associated with water are not new: there are reports of outbreaks from before 2000.
Dr Weinbren said that there may be a ‘missed epidemic’: the literature is dominated by infections caused by resistant strains, so many other instances of waterborne Pseudomonas infections that are sensitive to
outlets. Both Pseudomonas and Legionella have been found inside the complex mechanisms of infra-red operated taps. Thermostatic mixer valves and EPDM (synthetic rubber) hoses, which use materials susceptible to biofilm
formation, can also be problematic. Also speaking at the meeting,
microbiology consultant and former directorate manager of the Department of Medical Microbiology at Royal Liverpool and Broadgreen University Hospitals Dr Tom Makin noted that many of the control mechanisms for Pseudomonas are similar to those for Legionella.
Avoidance of build-up of biofilm is crucial, he said, with regular flushing of outlets the key to preventing stagnation. He also stressed that: ‘You cannot be
certain that outlets are completely clear of Pseudomonas and Legionella just by doing risk assessments and testing. Water samples can only ever provide a snapshot in time. This is because sampling will only pick up free-floating forms, so sampling must take place when the outlet has been least used.’
Other control measures include avoidance of aerators, flow straighteners, overly-complex infra red outlets, TMVs and flexible hoses. Patient secretions should not be put down sinks, Dr Makin said, and cleaning staff should be trained on the correct cleaning procedures for taps and sinks.
In most situations the only way of being absolutely sure that water is free of bacteria is to install point-of-use (POU) filtration incorporating 0.2μm membranes. This is confirmed in the new guidance, which recommends POU filters on outlets as an option in this context and as a possible solution in the event of contamination. E
The Dublin Masterclass, chaired by Hilary Humphreys, professor of clinical microbiology and consultant microbiologist at Beaumont Hospital, Dublin, was one of an ongoing series of free educational seminars on water quality and the prevention and control of waterborne pathogens.www.specialistmasterclasses.com/ home.htmlSusan Pearson BSc is a freelance journalist specialising in medicine and the environment.
Waterborne Pseudomonas bacteria are a common source of infection in care settings. Susan Pearson reports
Cut it out: waterborne Pseudomanas bacteria can be blocked by installing water filters
p29 EHN04_Feature_v2.indd 29 24/04/2013 12:20