In the first in a series of three articles planned to run in HEJ in coming months, Dr Mike Weinbren, a consultant medical microbiologist at King’s Mill Hospital in Sutton-in-Ashfield in Nottinghamshire, and a Specialist Advisor, Microbiology, on England’s national New Hospital Programme, examines some of the major health risks to patients and staff from airborne and waterborne microorganisms transmitted via hospital wastewater systems.
Depending on how you look at it, the New Hospital Programme is either the perfect storm, or the perfect opportunity. England is set to build at least 40 new hospitals by 2030, a significant proportion of healthcare real estate. Expected to last for at least 60 years, these hospitals should still be operational in 2080. Such facilities will be operating over a period when the threat from antimicrobial resistance is likely to be at its fiercest. The highly influential review on antimicrobial resistance (AMR), ‘Tackling drug-resistant infections globally’, chaired by Lord Jim O’Neill, predicts a bleak future should there not be a major change in current practice.1 Predicting a potential end of the antibiotic era by 2050, the estimated economic impact globally will be five hundred trillion dollars, and at least 10 million extra deaths year-on-year globally.
Undermining advances in medicine
Antimicrobial resistance does not just affect the treatment of patients with infections, but also threatens to undermine most of the advances in medicine. Antibiotics are used to protect individuals during periods of immunosuppression due to cytotoxic drugs, as well as procedures requiring implants, i.e. prosthetic hip surgery. The past 15 years have seen an explosion in reports linking transmission of highly antibiotic-resistant organisms from wastewater systems to patients, in the most sophisticated healthcare economies around the world. The human gut contains more bacteria than there are people on the planet, most of which are Gramnegative organisms. It is among the latter group of organisms that the threat of the end of the antibiotic era emanates – and because these may be naturally carried in the human gut, they inevitably enter wastewater systems. The seriousness of the issue is exemplified by a small, but increasing number, of augmented care units globally moving to water-free patient care to terminate otherwise intractable outbreaks of highly resistant organisms originating from the wastewater system.
An intangible?
For many, the consequences of antimicrobial resistance do not seem tangible. When a patient has a severe infection, irrespective of the source, the invading organism will gain access to the bloodstream. If a blood sample is collected and cultured the organism and its antibiotic sensitivity pattern may be determined. Patients presenting with sepsis are started on empirical antimicrobial therapy – a best guess before culture results are available. A multi-centre study from the USA found that 20% of patients with bloodstream infection were on ineffective antimicrobial therapy, as judged by laboratory testing.2 Patients on ineffective antimicrobial therapy had a higher mortality irrespective of underlying condition or the presence of sepsis. As rates of antibiotic resistance increase, so will failures in empirical therapy. Patients are dying now as a consequence of antimicrobial resistance. This is not purely a scenario which happens when no effective antimicrobial agent is available. The consequences of AMR are tangible now
Wastewater systems
Although early civilisations including the Romans understood the requirements for separating clean water from human waste, the concepts of sanitation were lost in the mists of time until the advent of the industrial revolution. The large influx of rural populations into cities lacking both safe water and sanitation resulted in faecal contamination of water supplies, and diseases such as cholera becoming rife. The ‘Great Stink’ of 1858 was the driver for Sir Joseph Bazalgette to be employed to build the sewerage system for London, which still stands today. In 2007 the British Medical Journal asked readers to nominate the most important medical milestones since the forerunner of the journal was first published in 1840. Out of a shortlist of 15 topics, clean water and sewage disposal – the ‘sanitary revolution’ – won.
Two notable reports of outbreaks were with highly antibiotic-resistant strains of Pseudomonas aeruginosa. The first, by Hota et al (2009), showed that splashes from clean water hitting a contaminated drain could disperse organisms at least a metre.3 The second, from Breathnach et al (2012), described how the wastewater system could act as a superhighway for moving organisms around a healthcare facility.4
Manchester Royal infirmary has been an ongoing source of Carbapenemase Producing Enterobacteriaceae (CPE) for over a decade. This has had a huge financial impact, as well as a detrimental effect on patient care and outcomes. The hospital’s wastewater system has had a significant role in driving this continued outbreak.
The risk from wastewater systems can arise anywhere in the building, and does not need to be in the patient’s immediate environment. The photo in Figure 1 shows how patient water jugs are traditionally filled, with placement in a sink. As the blue arrow shows, this results in the base of the jug contacting the drain and associated organisms. Outbreaks have been linked to this practice, with the jug transporting the organisms to the patient environment. Without new designs this method of filling receptacles with water is likely to continue
Microorganisms using wastewater systems as a superhighway?
It would be comforting to believe that when material disappears down a drain it is no longer a threat. However, this is not the case. There are three common potential associated ways that microorganisms effectively utilise wastewater systems as their own ‘superhighway’, as follows:
1: Updraught when a toilet is flushed
When a toilet is flushed on the second floor of a building, for instance, and faeces and water enter the main sewage stack, one might rightly expect that the water and faecal material will fall down the stack due to gravitational forces. Indeed this occurs, but the body of water and faecal material displaces air upward within the stack, which creates an updraught that generates an aerosol of faeces and water, which can spread to multiple stories within the building. In the first SARS outbreak, biologically active virus was excreted from the gastrointestinal tract. An immunocompromised patient infected with the virus living in a high-rise apartment in Amoy Gardens in Hong Kong (Figure 2) caused an outbreak among residents of the building. The residents living on the same floor of the building who shared services such as lifts were not affected. The pattern of spread was to residents living immediately above and below the apartment.
The investigation into the outbreak attributed the cause to spread via the wastewater system. The bathroom floors in the flats were meant to be wet mopped, and were linked to the wastewater system via a U-bend. Most residents did not wet mop the bathrooms, so the U-bend was dry. When the index cased used toilet and aerosol of faeces and virus ascended and descended the main sewage stack, the viral aerosol entered the bathrooms of the residents above and below through the wastewater system. Work conducted in Edinburgh using bacterial suspensions has shown that indeed aerosols are generated which can ascend several stories in a building, and enter other sewage pipes entering the main stack.
2: Spread along pipework
Utilising a gallery of sinks, as shown in Figure 3, researchers inoculated the U-bend of the sink on the right with a tracer organism. Within seven days the same organism could be found in the U-bend of the three adjoining sinks. To reach the U-bend of the sink to the left required organisms to traverse an uphill gradient.
3: Escaping from the U-bend
Research from the US (see Fig 4) has shown that placement of bacteria alone in a U-bend poses no risk by itself. However, the addition of a carbon source results in a dramatic development – bacteria in the form of biofilm will ascend the drain to reach the sieve in a sink at the rate of 1 mm / hour. Water from an outlet hitting the drain will result in widespread dispersion (up to 2 metres) of the bacteria
Thus, bacteria can use the wastewater system as a superhighway to spread within a healthcare facility, and to escape from there to cause infection and spread antimicrobial resistance.
Much effort and resource to counteract the threat of AMR is going into developing new antibiotics, antimicrobial stewardship, and infection control. However, counteracting the risk from healthcare wastewater systems has yet to be addressed. Germany has produced guidance in this area. The O’Neill report viewed issues on sanitation to be restricted to developing countries,1 but this is not the case. In the most sophisticated healthcare facilities globally, faecal organisms are being transmitted to patients from wastewater systems. England has a great opportunity to lead globally in this area. The first step is acknowledgement of the issue across the industry, including by manufacturers, producers of guidance, architects, design teams, construction companies, maintenance personnel, and clinical teams.
Dr Mike Weinbren
Dr Mike Weinbren is a consultant medical microbiologist with a special interest in water and wastewater systems. The Chair of the Healthcare Infection Society Working Party on Water/Wastewater, he has authored a number of publications in this area, and contributed to HTM 04-01 and the new British Standard BS 8580-2: 2022. He is currently employed at King’s Mill Hospital in Sutton-in-Ashfield in Nottinghamshire by Sherwood Forest Hospitals NHS Foundation Trust, and is also a Specialist Advisor, Microbiology, on the New Hospital Programme.
In the next two articles, two of Dr Weinbren’s industry colleagues will look, respectively, at current issues with the design, construction, commissioning, and occupation, of buildings in relation to wastewater systems, and at potential future areas for research
References 1 Tackling drug-resistant infections globally: Final Report and Recommendations. The review on Antimicrobial Resistance, chaired by Jim O’Neill, Wellcome Trust and HM Government, May 2016. https:// tinyurl.com/bp96dyzb 2 Kadri SS, Lai YL, Warner S, Strich JR, Babiker A, Ricotta EE et al. forming the National Insititutes of Health Antimicrobial Resistance Outcomes Research Initiative (NIH-ARORI). Inappropriate empirical antibiotic therapy for bloodstream infections based on discordant in-vitro susceptibilities: a retrospective cohort analysis of prevalence, predictors, and mortality risk in US hospitals. Lancet Infect Dis February 2021; (2): 241-251. 3 Hota S, Hirji Z, Stockton K, Lemieux C, Dedier H, Wolfaardt G et al. Outbreak of multidrug-resistant Pseudomonas aeruginosa colonization and infection secondary to imperfect intensive care unit room design. Infect Control Hosp Epidemiol 2009; 30:25e33. 4 Kotay S, Chai W, Guilford W, Barry K, Mathers AJ. Spread from the sink to the patient: In situ study using green fluorescent protein (GFP)-expressing Escherichia coli to model bacterial dispersion from hand-washing sink-trap reservoirs. Appl Environ Microbiol 2017; 83:e03327-016.