WATER HYGIENE AND SAFETY
50000 45000 40000 35000 30000 25000 20000 15000 10000 5000 0
Pre Flush Outlet and Pre Flush Filter Pre Flush filter Pre Flush
retention of system Legionella bacteria throughout their deployment cycles. One sample did provide a positive
Figure 4: Filter Assurance Samples June 2021. (N.B. Filter pre flush all below detectable levels.)
the ward when filters were installed (and each time they were replaced), pre-flush sampling was also undertaken through the filter, as well as the system. Continued ‘not detected’ results post-filter provided the assurance required while ongoing works were being undertaken on root cause analysis.
‘When you think it can’t get any worse’ To compound the challenges associated with this ward, it was converted into a ‘COVID-positive’ ward on New Year’s Day 2021, and remained so until April 2021. This added to the challenges in managing Legionella control – from simple access issues for flushing or monitoring temperatures, through to being able (or not) to make any physical changes to the plumbing.
When the ward became accessible,
despite COVID patients still being treated on the ward, Lakeside and the Authorising Engineers undertook a site visit to review the pipework, and the potential for pipework re-configuration was discussed. It was noted that this ‘challenging’ ward was the only area in the hospital with plastic pipework, and the only one with ongoing bacterial concerns. During this meeting it was agreed to remove parts of the pipework and undertake swab sampling on it and associated fittings to confirm whether this combination of conditions was purely coincidence. The swab results identified that the pipework was clear for Legionella. Some of the fittings, however, were positive for L. anisa.
Swab data at and results The swab data and results led to a further meeting with the Trust, tenants, and Authorising Engineers (one from Lakeside Water, one from the client, and one from the tenant). The group reviewed some pipework and fittings that had recently been removed from the system. At this point it was discovered that a large amount of jointing compound was on the outside and inside of the plastic pipework;
24 Health Estate Journal March 2022
concerns were also raised about the jointing material used. It was agreed by all that the plastic pipework and fittings with associated jointing compound would have to be removed to reduce the Legionella risk. Had the ward been piped correctly during the original installation, the scale of the Legionella risk would have been drastically reduced, if not removed entirely. The re-plumbing of the system was
due for completion by the middle of September 2021, and the early results from this suggest that the positivity rate has dropped by over 95%.
‘Lies, damned lies and statistics’. Figures 1a and 1 b highlight the interaction of L. anisa, and L. pneumophila SG1 and SG2-15 with the different chemicals that have been applied to the system.7
Figure
1a/1b shows how L. anisa appears to out-compete the other legionella bacteria present in the system; some of these come to the fore as L. anisa counts reduce, this is most prominent in the pre-flush results. The datasets in Figures 2a and 2b show
how L. anisa typically behaves on this site in areas where there are less competing legionella bacteria in that part of the system. Note how, even post- the remedial works, the L. anisa infection appears to be coming back in certain areas of the system. Figures 3a and 3b show a prime
example of how the L. pneumophila serogroup 1 respond to the different treatments both pre- and post-flushing.8 Notice how in April and May 2021 the increase pre-flush starts to present itself post-flush, with no L. anisa competing with the L. pneumophila SG1 strains for hold within the system. Interestingly, and curiously, L. anisa seems to have established itself around this asset post- the re-plumbing works, as demonstrated by the October 2021 result. The data in Figure 4 demonstrate how
the T-safe filters successfully protected patients once the issues were identified and the filters were deployed. Installed for over 12 months, the filters offered total
result of 21 CFU/litre. This is exceptionally unlikely to have come through the filter, due to the nature of its design and function. If a filter was to fail, it fails catastrophically, allowing all pathogens through. The likely cause of this positive result is either retrograde or cross- contamination of the sample, at the point of sampling, transport, or analysis. The performance of the filter was not impacted by the various treatment processes deployed, or the varied Legionella counts, which ranged from not detected up to over 40,000 CFU/L.
What was the cost to the Trust? The title of this paper asks questions about the cost of not doing things right. The ‘additional’ monetary cost to the Trust on this project included: n Daily flushing works over 21 months, costing around £150,000.
n Monthly sampling of the ward over 21 months, costing around £30,000.
n Four systemic disinfections, costing around £5,000.
n TMV servicing and remedial works, costing over £5,000.
n New calorifiers, costing around £30,000. n New Chlorine Dioxide system, costing around £30,000.
n New water tanks and booster systems, costing around £40,000.
n T-safe PoU filters for numerous cycles, costing £25,000.
n Re-piping of the system, costing around £50,000. These costs amount to around
£350,000 to date, and the situation continues to be monitored, adding more to the ongoing cost of ‘not doing things right first time’. There is also an obvious human
cost involved in this – not only from the disruption to the ward and added pressures on ward staff, but also to the patients and families in the decanting of the ward to another hospital location 30 miles, and a 50-minute drive away, from the current location.
What questions has the experience raised? There are clearly some root causes to the issues raised in this review – from specification issues around calorifiers and the use of plastic pipework, to questions about the impact of sampling 48, 72, 96, or 120 hours post-chlorination, and the impact on results and the resistance of L. anisa to a range of chemical and thermal treatments.9 Other interesting patterns in the dataset
raise further questions. It is clear to see from the full dataset on this site that L. anisa and L. pneumophila can co-exist in low numbers. However, when the counts
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Outlet 3 Hot Outlet 3 Cold Shower 2
Outlet 4 Hot Outlet 4 Cold Shower 3
Outlet 5 Hot Outlet 5 Cold Shower 4
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Outlet 8 Hot Outlet 8 Cold Shower 7
Outlet 9 Hot Outlet 9 Cold Outlet 10 Hot Outlet 10 Cold Outlet 11 Hot Outlet 11 Cold Outlet 12 Hot Outlet 12 Cold
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