Aspects and problems associated with the water services to be considered in intensive care units

Abstract

Background

Water is a product taken for granted and assumed to be a safe commodity in intensive care units (ICU). Biofilm readily becomes established in complex water services presenting a risk to vulnerable patients. Harboured within biofilms are opportunistic pathogens which can be transmitted via hand contact, splashing, aerosol and indirect contact through medical equipment. Evidence linking the role of water services in transmission of infection to patients in ICUs has increased in recent years.

Aims

This research based commentary set out to identify current problems with water and wastewater systems in ICU settings.

Methods

Databases and open source information was used to obtain data on current water and wastewater-related issues in ICU settings. This and the authors experiences have been used to describe current challenges.

Findings

the authors found a number of problems with water systems in ICU to which there has not been a cohesive response in terms of guidance to support users and designers. The resultant void permits new projects to proceed with suboptimal and designs which place patients and staff at risk.

Discussion

Hand hygiene stations are frequently misused or close enough to patients such that splashing poses a transmission risk. The wastewater system (drain) also presents a risk, from where Gram-negative antibiotic resistant organisms may be dispersed resulting in untreatable patient infections. The water and wastewater system provide a superhighway for the movement of pathogenic microorganisms and these risks need to be addressed if we are to safeguard vulnerable users in ICU.

Introduction to water and associated problems in ICU

Whilst water is essential to life, in healthcare the lack of training, education and familiarisation with current guidance means that water and waste services are dispersing microorganisms including those that are antimicrobial resistant and resulting in infections (Mogasale et al., 2018) Waterborne infections are common even in well controlled healthcare systems and equally concerning is the recognition that wastewater organisms are infecting patients. (Parra et al., 2020) These infections are reminiscent of the 19th century when faecal contamination of water supplies caused disease, only now water contaminated with faecal organisms is infecting critical care patients in the most sophisticated healthcare systems (Jung et al., 2020).

Failure to address these issues not only puts the individual vulnerable patient at risk but threatens the wider population due to the dispersal of highly antibiotic resistant organisms (Ahmad and Khan, 2019).

Consequently some critical care units have reduced the number of water services including hand hygiene stations to prevent the of dispersal of organisms. (Hopman et al., 2017) Whilst these units are considered to provide “water free” patient care, a limited number of water services are still provided for hand hygiene purposes. The reduction of water services simultaneously removes the risk from both the outlet and from the wastewater (drain) related to hand the wash station.

Methodology

A narrative review was performed using relevant search terms: intensive care unit OR critical care unit AND design OR design guidelines OR design criteria OR water outbreaks OR water system design OR water free patient care, OR sinks/water/drainage OR wastewater. Pubmed was searched for guidelines, reviews and original articles detailing recommendations for intensive care patients. Published data were checked for additional references and duplicate publication.

What are the risk from water services?

Incoming mains water contains Opportunistic Premise Plumbing Pathogens “OPPPs”, naturally found in the aquatic environment which resist low level chlorination in water treatment plants, survive in low nutrient conditions and form biofilms. (Falkinham et al., 2015) These organisms invariably enter healthcare water systems in small numbers in the incoming mains water and water system should be designed and maintained to minimise the risk of microbial growth and biofilm formation (DHSC, 2016; HSE, 2014).

However, the periphery of the system (last 2 m) is much more difficult to maintain biofilm free as maintaining conditions which preclude biofilm formation are challenging as is the control in medical equipment that requires water.

Failure to comprehend the inherent water risks resulted in a global outbreak with Mycobacterium chimera from cardiac bypass heater water coolers which were initially contaminated during the manufacturing process (Sax et al., 2015).

Regulations require that water should be safe for immunocompromised patients and the microorganisms should be controlled in the water such that they do not multiply and cause disease. (UK Govenrment, 2007) What may be seen as safe practices in a home environment are not the case in a clinical setting, but this distinction may not be obvious to staff. Therefore, we must train and educate staff, so they understand the risks of water and the consequences of their actions if transmission of infection through water is to be controlled.

What are the routes of transmission?

Water by its very nature aids dispersal of organisms. Water carries microorganisms over vast distances from reservoirs to buildings where biofilms grow and disperse their progeny. (Capelletti and Moraes, 2016) Outside of water systems, the ability of water to conform to any shape allows it to flow into crevices where biofilm forms. Just like in our homes, the presence of sealant around a sink or a wet room will eventually allow ingress of water and retention of moisture and microorganisms will grow on the nutrients hat are supplied and will be transmitted to patients (Seiler et al., 2020).

Splashing will disperse water droplets containing microorganisms at least 2 m from the outlet or surface of the sink/drain and patients and medical equipment are frequently located within this 2 m splash zone (Inkster et al., 2021).

Aerosolisation causes the bacteria within water to become airborne and Legionella plumes from cooling towers have infected individuals 10 km away. (Fennelly, 2020; Nguyen et al., 2006) Ward showers are a significant risk for aerosolization and other sources such as hand wash basins or flushing toilets cannot be excluded. (Bollin et al., 1985) Small leaks from cardiac bypass heater coolers were sufficient to cause aerosolization of mycobacteria which became a worldwide problem (Walker et al., 2017).

Contact transmission?

Direct and indirect contact can complete the journey of organisms from the hand wash station to the patient. The sole purpose of a clinical hand wash station should be for hand hygiene and nothing else. However, Grabowski et al., found that hand washing accounted for only 4% of behaviours i.e. 96% of visits were for the wrong purpose. (Grabowski et al., 2018) This included using the hand wash basin as a shelf, washing equipment and disposal of fluids. Washing trays in tap water resulted in contamination with Stenotrophomonas maltophilia (Figure 1). When the tray was used for drug preparation either staff hands or equipment transferred the organism into a Hickman line resulting in a line infection. Controlling human behaviour is a difficult endeavour, but without the necessary training the findings of Grabowski et al., and others should not come as a surprise. (Grabowski et al., 2018) A hand wash station is often seen as a place of safety as it is linked to hand washing, a procedure which healthcare staff (as well as patients and the public) view as being the most effective means of preventing cross infection.

Figure 1.

Placement of materials on the hand wash basin surface that will not only lead to contamination but also lead to hand hygiene not being performed.

Re-fillable spray cleaning bottles represent another example of risk, becoming an extension of the water system. (Figure 2). In this case filling the bottle with tap water led to the fluid being contaminated with P. aeruginosa (>10⁸ organisms/L) (Weinbren, 2018) From a staff perspective filling a spray cleaning bottle in the home environment is not perceived as a risk and neither is washing an item at the sink. However, in a healthcare environment the consequences can be fatal, hence the requirement for more training and education.

Figure 2.

Spray cleaning bottle and microbial growth on the agar plates following culture.

What is the role of the wastewater system?

It is a daily occurrence to dispose of liquids in hand wash basins. (Feng et al., 2020) However, wastewater systems provide a superhighway for microorganisms to travel within the building resulting in patient infections. (Smismans et al., 2019) Carbapenemase producing Enterobacteriaceae in wastewater systems are increasingly recognised as a major risk factor in the propagation of antibiotic resistance (Breathnach et al., 2012).

The combination of several mechanisms facilitates this situation including;

• 1. When a toilet is flushed and water and faecal material enter the main sewage stack, gravity causes the water and faecal material to drop down the pipe. Simultaneously air is forced to escape upwards, creating a flow of water particles including faecal organisms to travel up several floors in the building to contaminate other parts of the hospital wastewater system (Wong et al., 2021).

• 2. Blockage of drainage systems in hospitals is common and creates a route of transmission of microorganisms across the drainage network (Vardoulakis et al., 2022).

• 3. Experimental models have shown that if the waste trap of one sink (connected via the drainage system to a gallery of sinks) is inoculated with a tracer organism, the same organism can be found in most other waste traps within a week (Mathers et al., 2018).

• 4. Disposing of carbon sources down a sink drain, will stimulate the growth of biofilm up the vertical section of the drain at a rate of 1 mm/hour (Kotay et al., 2020).

How do microorganisms escape from the drainage system and find their way to a patient?

The purpose of a waste traps is to provide a water seal to prevent escape of sewer gases, however the traps contain bacteria. (Aranega-Bou et al., 2018) In a drain located directly below an outlet bacteria grow up the trap to reach the sieve at the top of the drain. When water directly hits the drain organisms will be dispersed up to 2 m into the environment. Even when the drain is placed at the bottom of the sink but offset, dispersal of organisms still takes place. In the UK, the recommended design is for the drain to be located at the rear of the basin. Work has shown that a rear drain is effective at preventing dispersal of drain organisms providing drainage is not impaired. (Aranega-Bou et al., 2021) But impaired drainage with rear drains is common, as they usually lack a sieve. Items removed from waste traps include end caps from giving sets, razor blade covers, capillary sampling devices and intravenous connecting devices. (Figure 3) Drain hole sieves are available, but can become heavily colonised with biofilm, and therefore create their own transmission risk. (Walker et al., 2014) Clinical staff have not been taught the importance of reporting poorly draining sinks, so in practice blockages only tend to be reported when they have become so bad that no drainage occurs.

Figure 3.

Example of debris removed from the u bend.

Whilst disposal of fluids, including patient fluids/secretions, should not occur in hand wash stations it does happen. The design of intensive care units makes appropriate disposal of fluids more difficult as side rooms tend to lack ensuite facilities (as would be found inside rooms on a general ward). Instead, staff are required to take the most heavily contaminated fluids out of an isolation room, possibly contaminating the surrounding environment (through spillages and hand contact points eg door handles) then traverse a considerable distance before entering the dirty sluice. In the dirty sluice secretions may be dropped down the sluice hopper, generating splashing which can contaminate items incorrectly stored within the vicinity. Many sluices lack appropriate infection control governance including a flow from dirty to clean and appropriate storage facilities (Breathnach et al., 2012).

In general, anything which impairs wastewater drainage increases risk of dispersal of organisms. Non-biodegradable wipes frequently cause blockages of waste pipes in healthcare facilities. Incorrect disposal of items is further hindered by poor design/engineering practices such as incorporating 90° bends in the waste pipes from macerators (Weinbren, 2020).

Conclusions

Water services in intensive care units represent a risk to patients both from water quality arising from the outlet and the risk of dispersal of wastewater organisms. Intractable outbreaks with highly resistant organisms emanating from wastewater systems have been a driver for water free patient care. New guidance is urgently required to inform design in order to mitigate against these increasingly commonly identified risks.

ORCID iD

Teresa Inkster https://orcid.org/0000-0003-1608-5224