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When did pseudomonas become important? Rogers, D. E. (1959). "The changing pattern of life-threatening microbial disease." N Engl.

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Presentation on theme: "When did pseudomonas become important? Rogers, D. E. (1959). "The changing pattern of life-threatening microbial disease." N Engl."— Presentation transcript:


2 When did pseudomonas become important? Rogers, D. E. (1959). "The changing pattern of life-threatening microbial disease." N Engl J Med 261: Compared microbial causes of death between with E. coli deaths superseded by an unusual pathogen, Pseudomonas aeruginosa % of infections causing death arose in the community % hospital acquired

3 Is there a problem with P. aeruginosa?

4 Looked at another way QuarterP. aeruginosaAll bacteraemia% P. aeruginosa ,7812.1% ,4302.1% ,5522.7% ,8162.5% ,4402.2% ,3022.2% ,9842.4% ,1922.4% ,1292.2% ,9412.2% ,6562.6% ,8882.3% ,3032.0% ,3852.2% ,7282.8% ,5122.9% ,3272.1% ,1782.4% ,3832.9% ,4722.7% Grand Total15,231635,3992.4%

5 And looked at a 3rd way Between 2004 & 2008 the number of Pseudomonal bacteraemias increased by 24%



8 %20Final%20Copy%20of%20Tap%20Study%20Report_att1_HPA%20NI%20Tap%20Study%20Report.pdf

9 A new source of P. aeruginosa Wilson, M. G., R. C. Nelson, et al. (1961). "New source of Pseudomonas aeruginosa in a nursery." JAMA 175:

10 Welsh estates alert the home countries O.C. Durojaiye, N. Carbarns, S. Murray, S. Majumdar. Journal of Hospital Infection 78 (2011) 152–159. Outbreak of multidrug-resistant Pseudomonas aeruginosa in an intensive care unit. 6 August 2010 From the Chief Medical Officer Welsh Assembly Llywodraeth Cynulliad Government Cymru Cathays Park Parc Cathays Cardiff Caerdydd CF10 3NQ CMO(2010)13 WATER SOURCES AND POTENTIAL FOR CROSS INFECTION FROM TAPS AND SINKS

11 Water quality at the point of entry into NHS premises drinking water must be wholesome at the time of supply

12 The legislation Water Supply (Water Quality) Regulations 2000 (as amended in 2001, 2007 and 2010), which implemented the European Council Drinking Water Directive 98/83/EC Compliance with the quality standards is overseen by the Drinking Water Inspectorate Microbiological standards or Prescribed Concentrations or Values (PCV) Escherichia coli and Enterococci The standard is 0 per 100ml. Clostridium perfringens The standard is 0 per 100ml. Coliform bacteria The standard is 0 per 100ml. Colony Counts The standard is no abnormal change # -taste and odor problems #"no significant variation and no abnormal change is when all the results obtained in the two years (or in the results of the last 12 samples where less than this number has been taken in two years) are within plus or minus one order of magnitude of the mean for that zone Anon The bacteriological examination of water supplies, HMSO, London Report 71

13 Guidance on pseudomonads Drinking Water Safety-Guidance to health and water professionals, 2009 ( HTM 04-01, 2006 Provided water is supplied from the public mains and its quality is preserved by correct design, installation and maintenance, it can be regarded as microbiologically acceptable for use. Minimum hot water temp 55 °C at furthest point, delivered at 41°C twice weekly flushing WHO – Water Safety in Buildings, 2011 Hospitals need-water safety plans; higher quality than drinking water; water treatment at the point of entry; pasteurisation of hot water systems >70°C Other countries France

14 Colony counts and nuisance organisms total viable counts (TVC) aerobic colony counts (ACC) and heterotrophic plate counts (HPC) A heterotroph is an organism that cannot fix carbon and uses organic carbon for growth. organismfix carbonorganic

15 Sources of utilisable carbon in a hospital water distribution system Provider surface bore hole Added in distribution materials from construction Water Regulation Advisory Schemes ( Water Supply (Water Fitings) Regs 1999 the unintended Carbon content will vary in place and time

16 And then there is the plumbing

17 The natural history of pseudomonas and faucets 1 Water contains sufficient organic utilisable carbon for heterotrophic growth. P. aeruginosa is present in the provider supply, or poor separation of clean & dirty contaminates the faucet, or P. aeruginosa is introduced at installation/commissioning. Biofilm is formed and persists and gives rise to: planktonic & sessile populations

18 Factors contributing to contamination 1 Concern for hand hygiene increased the number of outlets and: reduces flushing increases relative dead legs Delays between installation-commissioning-use Circulation of hot water is between 60°C & 50°C Aerators and coarse filters increase surface area

19 Why does the Flying Fickle Finger of Fait also point at Thermostatic Mixing Valves(TMVs)?

20 Factors contributing to contamination- are TMVs and infrared taps an issue? Contamination occurs within the last 2 metres of the distribution system TMVs contain larger surface areas of polymers which will support growth through liberation of utilisable carbon Mixed water exiting a TMV is not hot enough to pasteurise Flows are reduced and less turbulence to scour biofilm P. aeruginosa comes pre-installed Installation may be incorrect Infra red switching taps contain polymer diaphragms adding to the utilisable carbon load

21 What has been done about the problem? Produced interim guidance to assist in the prevention of the problem Organisation-water safety plan Risk assessment Water testing Produce an appendix to HTM 04-01: The control of Legionella, hygiene, safe hot water, cold water and drinking water systems

22 What needs still to be done revise HSE L8 document to take into account water quality and opportunistic infection other than Legionella. Establish a standard for water AT THE POINT OF USE in healthcare premises. Hygiene Washer disinfectors Pharmacies


24 And thats all I have time for folks

25 Still to be achieved in water safety Encourage the industry to seek engineering solutions to the problem of tap & TMV design Commission research Materials Growth Biofilm

26 Utilisable carbon sources added from materials in buildings Water Regulation Advisory Schemes ( Water Supply (Water Fitings) Regs 1999 fitting approval showers thermostatic mixer valves (Buildcert, MES D08) material approval BS

27 England's DH responds



30 Diagram illustrating the components of a thermostatic mixing valve (TMV) & faucet Hot water circulates continuously with a minimum temperature at the most distant part of 55°C. On return to the heat exchanger or calorifier the temperature must not be below 50°C. Cold water distribution temperature must not exceed 20°C as this is the temperature above which Legionella will proliferate. An adjustable thermostatic regulator that will blend incoming hot and cold water supplies to achieve an output at the faucet of between 41 and 43°C. The designs will require water to be provided above a certain pressureto function correctly. The tap controls the flow at the faucet. Where these are operated by infrared sensors and an electronic solenoid, additional polymer surfaces are introduced together with a residual volume at a temperature that will encourage growth. { The distance between the TMV and the tap or faucet can be critical. Water leaving the TMV is at most 43°C which is not sufficient to pasteurise. It will rapidly fall to ambient temperature and if contaminated will allow the proliferation of biofilm. Some devices incorporate the TMV within the tap design to minimise this distance. The flow straightener, inserted at the tip of the faucet to reduce splashing. Often complex designs and are where scale and biofilm accumulate. They are always the leading suspect where there is a problem with P. aeruginosa. They are removable and manufacturers are producing designs of spout without them. The combination of water, air and utilisable carbon make them irisistable to P. aeruginosa.


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