WATER SYSTEM HYGIENE & SAFETY Pseudomonas aeruginosa bacteria.


dramatically compromised. Sampling is intended to help healthcare


providers establish whether the water in augmented care units is contaminated with P. aeruginosa, in which case the question here is why the requirement for sampling as per the HTM 04-01 Part B is as follows: Appendix D Testing for P. aeruginosa “If test results are satisfactory (not detected), there is no need to repeat sampling for a period of six months – unless there are changes in the water distribution and delivery system’s components or system configuration (for example, refurbishments that could lead to the creation of deadlegs) or occupancy.


“However, the WSG could indicate that water sampling is required within six months if there are clinical evidence- based suspicions that the water may be a source of patient colonisation or infection (that is, with P. aeruginosa or another potentially waterborne pathogen).”5 We wonder whether – knowing there


may be clinical evidence-based suspicion of contamination as mentioned above – feedback from the Water Safety Group would in fact be considered too late for further sampling to be undertaken to identify the presence of P. aeruginosa? Biofilm build-up (which may contain P. aeruginosa) can be evident within weeks under ideal conditions.


Need for thought and organisation Sampling and re-sampling in accordance with the HTM 04-01 for P. aeruginosa in high-risk areas, including augmented care, require thought and organisation – which involves working closely with augmented care wards, clinical staff, sampling


44 Health Estate Journal March 2024


contractors (often third-party companies) and Estates department personnel – who would carry out the necessary remedial works on contaminated outlets. Prior to sampling for P. aeruginosa, the outlets need to be isolated as per HTM guidance for a period of, preferably, no use (at least two hours or preferably longer) or low use. This is very difficult to achieve in augmented care areas, and often samples need to be taken early in the morning in such clinical settings. In my past personal experience, I have collected samples in the middle of the night to reduce unnecessary disruption to clinical use of outlets. The overall point here is this – to carry out sampling correctly, the involvement of several departments is necessary. In addition, when we look at P. aeruginosa re-sampling strategy – whereby it is necessary to obtain three sets of pre- and post flush non-detected results on separate hot and cold-water distribution systems, the whole sampling strategy becomes a very lengthy process – especially when contaminated outlets have been repeatedly identified. The re-sampling requires the first set


(pre- and post-flush) to be collected post-remedial work at three days, and then two weeks later, with the final set four weeks later. In all this amounts to six or several weeks where clinical outlets are often fitted with point-of-use filters to ensure patient safety until a final set of re-sampling gives the Infection Prevention and Control team the required assurance that the outlets are free of P. aeruginosa bacteria. Also, quite frequently the re-sampling


strategy is brought back to stage one – due to persistent ongoing contamination with P. aeruginosa bacteria in biofilm. Difficulties accessing the outlet to carry


out remedial work, or delays in contractors attending to carry out remedial work or sampling, can further delay the outlet being clear of the contamination. Of course, we understand that the HTM 04-01 is purely guidance, and we can deviate from it on the basis that we can implement more robust procedures of control than those recommended in it. However, day to day, the clinical environment in high-risk areas such as augmented care is very demanding for clinicians, and much of the time it can be difficult to access outlets to collect water samples for clinical reasons – such as being unable to access them due to patients’ condition. We can thus understand that if the area is deemed to be clear of P. aeruginosa (at the time of sampling), and laboratory analysis has provided evidence of non-detection for P. aeruginosa (PA), the opportunity to leave this area alone for six months is one likely to be welcomed. The re-sampling strategy highlights the


fact that once any P. aeruginosa bacteria present in biofilm take hold in the water system (or contamination occurs as a result of insufficient hygiene practices), it is difficult to remove them, especially when we provide the biofilm with ample time to establish itself during the six-month period when no sampling is being carried out. We also know that where a ‘positive’ outlet is identified, a point-of-use filter is fitted to protect the patient. However, this creates another problem – in that it limits water flow, and may result in there being no sense of urgency to carry out remedial work, given that the POU filter is providing protection. The result may well be further biofilm accumulation.


A different approach? Should we consider and adopt the same sampling strategy for P. aeruginosa as we do for Legionella pneumophila? HTM 04-01 Part B outlines the following strategy for Legionella sampling: “Legionella monitoring should be carried out where there is doubt about the efficacy of the control regime, or where the recommended temperatures, disinfectant concentrations, or other precautions, are not consistently achieved throughout the system. The WSG should use risk assessments to determine when and where to test, which may include the following circumstances: n When storage and distribution temperatures do not achieve those recommended, and systems are treated with a biocide regime, testing should be carried out monthly, although that frequency may be altered depending on the results obtained.”


The strategy for Pseudomonas aeruginosa sampling should reflect the P. aeruginosa risk assessment, as stated in British Standard BS 8580-2 and HTM 04-01.


Creative Commons SA 2.0 Generic / Denise Chan


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