Although Pseudomonas and other infections have long been accepted as an endemic hazard for patients in intensive care and other high dependency units, the last decade has seen increasing worldwide recognition of the role of water in the transmission of these nosocomial organisms. SUSAN PEARSON reports.
As the evidence in the literature piles up, this new understanding has led to the development of new measures to control such outbreaks and protect vulnerable patients. Patients with deep and extensive burns, for example, are particularly vulnerable to waterborne infections during hydrotherapy, yet many outbreaks of infection occur in burn care units due to ignorance of the source of opportunistic pathogens and many could be avoided with appropriate prevention methods, according to leading European burns injuries specialist Rudi Deleus. Hydrotherapy offers an important contribution to wound care and healing, and is widely used in Europe and the US. However, its use remains controversial because the risk of infection can lead to significant mortality levels. What is crucial in allowing patients to benefit from the advantages of hydrotherapy, said Mr Deleus, is understanding and containment of hazards such as transmission of pathogenic organisms between patients and healthcare workers, transmission between patients from contaminated equipment and, often underestimated, contaminated tap water. Speaking at a recent waterborne infection masterclass, where discussion focused on identifying and finding solutions to microbial contamination of hospital water, Mr Deleus described how his burns intensive care unit at University Hospital, Leuven in Belgium had overcome problems with contaminated water to deliver safe hydrotherapy for patients. Head nurse at the unit, Mr Deleus is also a member of the European Burns Association, the Belgian Association for Burn Injuries, the Belgian Scar Academy and VSBN (the Netherlands United Association of Burn Centres). Hydrotherapy allows mechanical cleansing of wound surfaces to reduce the bacterial load and debris to stimulate healing. Simple sponging with large amounts of water, Mr Deleus explained, can provide significant cleansing for large wounds such as deep cavity wounds which are particularly awkward to clean. Physiotherapy during hydrotherapy is also much easier than when a patient is bandaged, especially for burnt fingers, hands and articulations, while comforting basic hygiene, such as washing and shaving, is also easier to carry out on a stretcher than in a patient’s bed. At Leuven’s 14-bed mixed ICU, which looks after a broad scope of surgical and wound trauma patients as well as burns victims, guard stretchers are deployed for hydrotherapy rather than Hubbard tanks. This allows faster decontamination times between each use and more patients to be treated each day. Water is discharged directly to the sink without connection to the mattress. However, within a few years of opening, this new unit was confronted with contaminated tap water. “Because we place a high value on hydrotherapy as an advantage in wound care rather than a practice to avoid, we had to learn to cope with the threat and find a way to safely shower our patients,” said Mr Deleus. He cited a North American survey of hydrotherapy in modern burn care1 which showed that while 50% of burns centres using hydrotherapy carried out routine culturing from their equipment, only 18% checked their tap water. This and other studies have found Pseudomonas as the most common major cause of sepsis. In a report from the Myeloma and Transplantation Research Center at the University of Arkansas for Medical Sciences in the US,2 Pseudomonas aeruginosa alone has been implicated in an estimated 1,400 deaths from waterborne nosocomial pneumonias each year in the US. Mr Deleus emphasised: “If tap water is able to kill patients from pneumonia, it will definitely have a deadly effect on large wounds in critically ill patients. Unfiltered tap water is not clean enough to wash the large wounds of our immunocompromised patients. We must be sure the water we use is always clean.”
A safe approach
His team’s approach to providing safe hydrotherapy for patients includes frequent water sampling to check tap water, equipment and personnel, and water filtration using high grade sterile filters. At Leuven, kilometres of galvanised iron piping allow a build-up of biofilm at rusty junctions and in system “dead legs” containing standing water. Difficult to treat even with chemical disinfection or heat treatment, these slimes are ideal breeding grounds for organisms such as Pseudomonas. Loosening from time to time to colonise the whole system, bacteria can appear at points of use intermittently, which means “frequent culturing is the only way to detect the problem”, Mr Deleus told the audience. The Leuven team have instigated two approaches to deal with the problem. Where possible, the galvanised iron plumbing has first been changed to PVC and later to polyethylene, to eliminate the problem of rust and provide a smoother surface that is less adhesive for biofilm to cling to. Just as important is the use of sterile grade water filters such as Pall- Aquasafe disposable showerheads, which incorporate a 0.2 μm filter. This protects patients from bacteria and protozoa, is resistant to chemicals used for disinfection and can be used safely for 14-31 days. Pre-filtration of the water supply with a 0.5 μm filter for both hot and cold water has also been installed to remove larger rust debris, which prolongs the life of showerhead filters. Wounds are cleansed with filtered water containing a 0.05% solution of chloroxidine, which is used more for its soap effect to remove fatty creams than for disinfection, Mr Deleus said. “So after hydrotherapy we have a clean patient who returns to a room that has been cleaned in the meantime.”
Hand hygiene
A strong emphasis on disinfection and hand hygiene is also critical for delivering safe hydrotherapy. All equipment is disinfected between treatments and to clean the patients and renew their bandages sterile gloves are used by healthcare workers to prevent transmission between patients. Disinfection products must be safe and effective for all bacteria and fungi. A 3% solution of Dialox (acetic acid, peracetic acid and hydrogen peroxide) is used at Leuven, left in contact with surfaces for 20 minutes after manual cleaning, with particular attention paid to any tubing that may come into contact with patients. Mr Deleus emphasised another hazard of hydrotherapy: mattresses can harbour Pseudomonas in water soaked up during treatment. At Leuven the weight of the trolley cushions and mattresses are checked weekly. Any that have become heavier from water gain are discarded. In the UK, recognition of water from taps as a potential source of Pseudomonas infections for vulnerable patients has been highlighted by the Department of Health as recently as August 2010.3 However, another speaker, Dr Michael Weinbren, Director of Infection Control at University Hospital, Coventry and Warwickshire (UHCW), told the audience there was no doubt that Pseudomonas in water had been causing problems for much longer. Also recommending filtration of tap water for use with patients in adult and neonatal critical care, Dr Weinbren described his experience with an outbreak of Pseudomonas in the general critical care unit (GCC) within weeks of the opening of phase II of the newly built UHCW hospital in 2006. Pseudomonas aeruginosa was isolated from six GCC patients on the same day, which might not usually be considered problematic, he said, as the new unit was an amalgamation of five previously separate units and this could be considered a potentially “normal” level of infection. However, Pseudomonas originating from contaminated tap outlets had already caused infections in the neonatal intensive care unit opened in Phase I of the build so further investigation was considered necessary. Preliminary infection control enquiries ruled out the more obvious modes of transmission and the investigation was extended to the water system to reveal a high titre of Pseudomonas aeruginosa in five out of 12 outlet samples. Yet more positive outlets were found subsequently. Timed samples – taken at zero, one and then two minutes found a high concentration of Pseudomonas in the first sample which then tailed off, indicating the contamination was at the periphery of the system and not in the main pipes. Both the thermostatic mixer valves (TMVs) which blend hot and cold water at the outlets and the flexible hoses that connect them to the sinks were found to contain Pseudomonas-rich biofilm. Further investigations demonstrated that tap water used for washing respiratory equipment (against policy) and bathing patients and water used for cleaning are likely to be a much higher risk route of transmission than from hands. Anonymous testing has revealed Pseudomonas-positive outlets in ITUs in other hospitals, Dr Weinbren said, yet these units may not recognise they have a problem with their water supply. “Pseudomonas from positive outlets may be missed because the organism is generally considered endemic to ITUs, but that doesn’t mean that isolates from water are not contributing to the burden in any unit. Water should always be considered as a contributing factor, and timing as well as sampling methods is critical as testing of only one or two samples could give false negatives.” Concluding, Dr Weinbren emphasised that “point-of-use filtration is the only real answer to producing large quantities of organism-free water for bathing patients.” :
References
1 Shankowsky H.A., Callioux L.S. and Tredget E.E. North American survey of hydrotherapy in modern burn care. J Burn Care Rehabil. 15(2): 143-6, 1994 2 Anaissie E.J., Penzak S.R. and Dignani M.C. The hospital water supply as a source of nosocomial infections. Arch Intern Med. 162: 1483-1492, 2002 3 Dept of Health. Water sources and potential for infection from taps and sinks (Gateway 14720; Aug 2010).
