Preparedness
The water safety group should have an agreed WSP that covers all care settings and is inclusive of a business continuity/contingency arrangement in preparation for the event that a water source, for example mains water, system water, tap water, cannot be used or an area cannot be used due to widespread known or suspected contamination.
All high-risk settings should have a setting-specific alert organism list for clinical isolates, which should be informed by the known historical epidemiology of that setting and allow for early identification of single cases of unusual environmental organisms.
As a minimum, this alert organism list should include
- Acinetobacter spp.
- Burkholderia spp.
- Chryseomonas indologenes
- Cupriavidus pauculus
- Legionella spp.
- Pseudomonas spp.
- Mycobacterium abscessus
- Mycobacterium chelonae
- Mycobacterium fortuitum
- Mycobacterium chimaera
- Mycobacterium mucogenicum
- Serratia marcescens
- Sphingomonas spp.
- Stenotrophomonas maltophilia
See Appendix 13 for more information on alert organisms including the locations/patient cohorts to which each apply.
Detection of a healthcare-associated infection incident or outbreak
Colonisation or infection of gram-negative microorganisms or non-tuberculous mycobacteria, isolated from a clinical sample in any patient should raise a high degree of suspicion of a healthcare associated environmental link and should be investigated/reviewed.
An environmental source should be considered when Enterobacteriaceae is isolated from a clinical sample and a data exceedance has been identified.
Isolation of Legionella spp. from a clinical sample in any patient indicates transmission from the environment and should be investigated as a possible healthcare associated infection incident if the incubation period fits and there is no established link to a community source. Further information can be found in the NIPCM A-Z of Pathogens for Legionella spp.
When determining HAI status, the incubation period should be considered, acknowledging the wide variation (a few hours to years) for environmental organisms.
- The incubation period for environmental organisms, particularly in high-risk groups may be relatively short and may not fit with the routinely applied 48 hour rule.
- Careful consideration should be applied when assessing an HAI in this category, recognising also that whilst a patient is receiving antibiotics which may assist in selecting the gram-negative organism more readily, it should still be considered and investigated.
Environmental organism outbreaks and incidents may occur over extended periods of time with significant time between cases. Consideration of an environmental link should be given to cases that have been identified over a wide time period.
Ensure that the risk of a false negative result is considered and further sampling discussed. This can be supported by taking a measured approach to sampling from the outset.
To assist with the management of incidents or outbreaks involving healthcare water system-associated organisms, a checklist is available in the resources section.
Investigation
- A multi-disciplinary IMT chaired by the ICD/ Consultant in Public Health Medicine (CPHM) should be established when any water associated infection risk is identified, to support the board and WSG to manage the incident.
- Healthcare water system incidents should be assessed according to the NIPCM healthcare Infection Incident Assessment Tool (HIIAT). For more information see Chapter 3 of the NIPCM.
- The Incident Management Team (IMT) should consider all possible sources including the environment (the water supply itself plus the plumbing components) and patients as both may be sources that can lead to ongoing transmission of waterborne infectious agents to other patients and further contamination of the environment.
- If it is essential for the water outlets to remain in use, point of use (POU) filters should be installed while investigations are ongoing and remedial actions are being considered.
Water testing in response to clinical cases
The IMT should agree a water sampling plan to identify and prioritise potential sources taking account of the following:
- the local water system for example the wash hand basin/shower in the patient's room
- outlets within ancillary facilities (including those shared by departments) such as staff kitchens, domestic services rooms (DSR), treatment rooms and preparation rooms, should be tested when investigating incidents/outbreaks due to the various different routes of transmission
- mains water supply
- the layout and schematics of the associated water system
- water associated equipment and procedures and any other sources of water exposure during patient care
- the potential involvement of refillable bottles
- historical water testing results/ trends
- known epidemiological information (including historical)
- the geographical distribution of any infected or colonised cases (during their entire healthcare journey)
Water samples should be taken before disinfection of the water system or equipment or before any other remedial actions are initiated.
As a minimum, a pre-flush sample should be taken from each outlet being sampled. Post-flush samples should also be considered.
Sampling instructions can be found in SHTM 04-01 Part C
- For sampling guidance specific to Legionella spp., BSI 7592:2022 ‘Sampling for Legionella bacteria in water systems – Code of practice’ should be followed.
Where no UKAS accreditation exists for specific healthcare water system-associated organisms, boards should still consider testing and can seek advice from ARHAI Scotland. See the UKAS Technical Bulletin for more information.
Environmental surface sampling in response to clinical cases
Environmental surface sampling (swabbing) should be carried out when there is more than one working hypothesis and an environmental source is suspected.
- Consider data exceedance (for example sporadic cases of colonisation or infection over a set time period which might occur over many years).
- An environmental sampling plan should be agreed by the IMT.
- Identify and prioritise potential sources or reservoirs taking account of:
- epidemiological information (including historical)
- historical environmental and water sampling results
- the geographical distribution of the infected and colonised cases throughout their entire healthcare journey
- Environmental sites would include any sites that are exposed to water.
- Environmental samples should be taken before environmental cleaning or decontamination occurs or any other environmental remedial actions have been initiated.
Closing an incident
When considering whether to declare an infection incident or outbreak as ‘closed’ or ‘over’ the IMT should be assured that transmission risks have been mitigated, including exposure from any remaining colonised or infected patients and that there is a surveillance plan in place to allow for early detection of any further potentially linked cases.