An Interview with Dr. Teresa Inkster a Consultant Microbiologist from NHSGGC
Know the First Signs of A Waterborne Outbreak & The Steps to Manage A Waterborne Outbreak
May 9, 2022
What was the first sign that your facility might be experiencing a waterborne outbreak?
In 2016 the hospital aseptic pharmacy unit reported high total viable counts (TVCs) from two clinical wash hand basins within the department. Whilst the preparation area itself was a water free zone staff had access to two CWHBs in the changing area and the corridor. Our microbiology laboratory identified these organisms as an unusual Gram negative bacteria called Cupriavidus pauculus. Following remedial measures including removal of one of the CWHBs, repeat water testing was negative and TVCs fell to zero. At the time a lookback was undertaken and we identified one previous patient case of Cupriavidus bacteraemia in a patient who had received a product from the aseptic pharmacy. An outbreak was declared two years later in 2018 following a 3rd patient case of bacteraemia.
What was the pathogen?
Cupriavidus pauculus was the indicator organism in this outbreak. It is a rare Gram negative organism formerly described as Ralstonia species. It is nutritionally versatile and can tolerate harsh environments. Prior to this outbreak, it had been reported in water sources such as ECMO, bottled water and hydropools. Subsequently, during the course of the outbreak, we saw patient infections due to other waterborne Gram negative organisms e.g., Stenotrophomonas maltophilia and Chryseomonas, Pseudomonas, and Acinetobacter species.
What were the first steps you took to remediate the outbreak? And any additional steps after that?
The outbreak centered around a children’s haemato-oncology ward. These patients are immunosuppressed and susceptible to infection so the initial steps were to provide a safe source of water for patients. This involved providing alternative means of hand hygiene, use of bottled or sterile water, and bathing with wipes, prior to the fitting of point of use filters (PALL) on taps and showers. We also undertook local chemical dosing of the water system with silver hydrogen peroxide. This method of control was unsuccessful and due to the extensive nature of the outbreak, we installed a hospital wide chlorine dioxide system in addition to replacing sinks and taps in this high risk unit. We also addressed structural abnormalities found in the drains.
Who was involved in the team to manage the outbreak?
The outbreak was managed by a multidisciplinary incident management team. Membership included the infection control team, clinicians, estates and facilities colleagues, hospital senior management, media officer, public health clinician and external supporting agencies i.e., Health Protection Scotland and Health Facilities Scotland. A subgroup of the incident management team was also established, this was known as the water technical group and included UK water experts. The role of this group was to investigate the extent of the water contamination, develop the hypotheses and implement control measures which included the complex installation of a chlorine dioxide system.
Was the source of the outbreak ever confirmed?
Several rare and unusual patient infections coincided with the same organisms being identified from the water and drainage systems. A small number were linked via typing but many were not. This highlights the complexity of biofilm and waterborne incidents. Our current approach to typing during such incidents involves selecting a single colony from an agar plate when in fact we should be selecting more (up to 20) to identify the many different strains we could expect to find where biofilm is implicated. It is likely our sampling strategy failed to identify many strains. Several issues were subsequently identified with the design, installation and maintenance of the water system which were factors in this outbreak. Once these issues were addressed infection rates decreased.
Do you have advice for healthcare facilities that have not experienced an outbreak?
The role of the water safety group is very important. The governance of this group and the roles and responsibilities of members should be clearly defined. Legionella risk assessments should be kept up to date and action plans developed from any findings, along with a water management plan. All sources of water in hospitals should be considered by the water safety group and it should also have clinical representation. Schematics of the water system should be available and I would also recommend having a supply of point of use filters so these can be rapidly fitted during an incident.
For more information on Dr. Inkster’s experience, please see her published works below:
Inkster T, Peters C, Wafer T, Holloway D, Makin T. Investigation and control of an outbreak due to contaminated hospital water system, identified following a rare case of Cupriavidus pauculus bacteraemia. J Hosp Infect. 2021 May;111:53-64. doi: 10.1016/j.jhin.2021.02.001. PMID: 33926650.
Inkster T, Peters C, Seagar AL, Holden MTG, Laurenson IF. Investigation of two cases of Mycobacterium chelonae infection in haemato-oncology patients using whole-genome sequencing and a potential link to the hospital water supply. J Hosp Infect. 2021 Aug;114:111-116. doi: 10.1016/j.jhin.2021.04.028. Epub 2021 May 1. PMID: 33945838.
Inkster T, Weinbren M. Is it time for water and drainage standards to be part of the accreditation process for haemato-oncology units? Clin Microbiol Infect. 2021 Dec;27(12):1721-1723. doi: 10.1016/j.cmi.2021.08.011. Epub 2021 Aug 14. PMID: 34400342.
Inkster T, Wilson G, Black J, Mallon J, Connor M, Weinbren M. Cupriavidus spp and other waterborne organisms in healthcare water systems across the United Kingdom. J Hosp Infect. 2022 Feb 15:S0195-6701(22)00043-3. doi: 10.1016/j.jhin.2022.02.003. Epub ahead of print. PMID: 35181399.
Thank you for your interest. We will be in touch soon.
Dr Teresa Inkster
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