1. Facilitator notes:
Legionnaires’ disease: Risk assessment, outbreak investigation and control
Session 5, Activity 2: Analysis and Interpretation of Laboratory Investigations
ECDC, 2012

2. Scenario
A single case in an elderly 78 year old female who developed LD 5 weeks after admission with a cerebrovascular accident, to high dependency ward Ward S (Bay 5) in Hospital H. There has been five other cases reported to the surveillance team with potential links to Hospital H.

3. Background case summary
Six cases had contacts with local hospitals within the incubation period.
Two cases - Strong association with Hospital H
No clinical sample.
Both used assisted baths.
L. pneumophila found in water samples during routine checks.
One case - visited hospital H
Other risk factors identified.
Two cases - visited hospital
Other risk factors.
One case - visited a different hospital.

4. Background: Hospital water system
Risk assessment - out of date.
No schematic of the water system.
There didn’t appear to be a regular scheme of descale, clean and disinfection of outlets, shower heads and flexible shower hoses.
No regular regime of temperature monitoring.
Deadlegs around the water system.
Poor documentation of issues (e.g. poor flow of water) and no follow up of actions.
Highlights:
Need to audit usage of assisted baths.
Introduce flushing of infrequently used outlets.
Survey wards for infrequently used outlets – dealegs.
Up to date schematic to identify deadlegs/blindends.
Regular maintenance is required to remove scale and scum which can encourage bacterial /biofilm growth.
Temperature monitoring to ensure there is temperature control throughout the system.
Documentation is necessary to enable audit of the work that is required and follow up to ensure the remedial work is completed.

5. Legionella results from environmental samples 1
Ward
Area Sampled
Temp.
Count
cfu L-1
Result
RS ward
WHB Hot tap Sluice 1
58.7
Not Detected
WHB Cold Tap Sluice 1
14.5
Arjo Bath tap 27
54000
L.pneumophila sg1 Benidorm ST42
Arjo Bath cleaning shower
160
Shower Bay 5
16000
WHB Hot tap Sluice 2
57.2
WHB Cold Tap Sluice 2 14
Shower ensuite side room
>10000
Ken ward
WHB Hot mixer post flush Sluice
61.8
WHB Cold tap post flush
18.3
KA1
WHB Hot tap post flush sluice
55.8
KA2
WHB cold tap post flush sluice
17.6
KD2
WHB sluice cold tap post flush
14.8
CM1
WHB sluice Hot tap post flush
31.4

6. Legionella results from environmental samples 2
Ward
Area Sampled
Temp.
Count
cfu L-1
Result
CM2
WHB sluice cold tap post flush
15.8
Not Detected
WHB sluice Hot tap post flush
37.3
CM3
15.1
ITU
WHB S/mix cold post flush
14.6
560
L.pneumophila sg1 Benidorm ST42
Outpatients
WHB Main reception ladies toilet Hot pre
38.8
600
RS ward
Female toilet Bay 3 hot
37.7
Side room 3 cold 28
3100
L.pneumophila sg1 Benidorm
Side room 3 hot 42
900
OPD Area A
Visitors toilet cold 17
Visitors toilet hot
48.5
OPD ECG room 1
cold 18
hot
36.7
280
Area D
Sluice cold
26.3
Sluice hot
50.4
These are the results from the initial environmental sampling immediately after cases who had strong association with Hospital H.
The assisted bath is particularly colonised and the temperature of the water sample from the bath tap is ideal breeding ground for bacterial growth.
Some of the hot tap temperature is not reaching the target minimum of 50. Need to ensure that there is a good flushing regime, whilst the HWS is being investigated to rectify the hot water temperature.
Some of the cold water is gaining heat- Look for insulation of pipework, look for plumbing faults.
Highlight the importance of monitoring (sampling & temp profile) of conventional separate hot and cold taps.
Because this is a very select number of outlets not representing the whole hospital, sampling strategy is to undertake wider sampling.
For areas where high Legionella positives have been reported, need to undertake a root cause analysis for that outlet.
Showerhead, hoses, TMV-dismantle, descale, clean & disinfect. Replace flexible hoses with solid copper pipe. Resample.

7. Task 1: 10mins
If you are the proper officer (chairing the outbreak investigation in the area), list what you would do. The hospital is still open to the public, what emergency control measures would you initiate within Hospital H? What would be your advice based on the environmental microbiology results?

8. What can you conclude from the findings during the walk around?

9. Case summary: Six cases had contacts with local hospitals within the incubation period.
Two hospital-acquired
no clinical sample
both used assisted baths.
L. pneumophila found in water samples during routine checks.
One case visited hospital
no clinical sample.
other risk factors
Two cases visited hospital
distinct strains from hospital strains.
One case visited a different hospital
distinct strain.

10. Task 2: 5mins
What conclusion can you make from this? Was the hospital the source of the Legionnaires’ disease cases? Why? (5mins)

11. Assisted (Freedom) baths

12. Facilitator notes:
Acknowledgements The creation of this training material was commissioned in 2010 by ECDC to Health Protection Agency (UK) and the University of Chester (UK) with the direct involvement of Louise Brown, Janice Gidman, Emma Gilgunn-Jones, Ian Hall (on behalf of the ECDC Legionnaires Disease Outbreak Toolbox Development Group), Tim Harrison, Rob Johnston, Carol Joseph, Sandra Lai, John Lee, Falguni Naik, Nick Phin, Michelle Rivett, and Susanne Surman-Lee. The revision and update of this training material was commissioned in 2017 by ECDC to Transmissible (NL) with the direct involvement of Arnold Bosman and Kassiani Mellou.