Biofilms a hidden problem in your water system?

Transcription

1 Biofilms a hidden problem in your water system? Jimmy Walker HPA Microbiology Services, Porton Down, Salisbury Dirty Little Secrets, 21st October 2010 Courtesy of Malcolm Greenhalgh

2 Rebecca Lacey Thanks to: Tom Makin John Lee Sue Surman-Lee Stuart Line Hans-Curt Flemming

3 Dirty little secrets in your water? 3

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5 Biofilms Microorganisms of interest in water systems What factors in a water system encourage bioflims? What impact does this have on patients and services in a hospital? Discuss some mechanisms of control 5

6 Biofilms are 3-D functional consortia of microbial cells, bound to and growing at an interface solid:liquid, solid:air, liquid:air, liquid:liquid). Such consortia are generally enveloped within extracellular polymers Individual cells within a biofilm are physiologically distinct from their planktonic counterparts 6

7 Biofilms are ubiquitous 7

8 Multispecies Examples of Biofilm 8

9 Biofilm Formation Flow in Fluid Phase Conditioning Film SUBSTRATUM 9

10 Biofilm Formation Flow in Fluid Phase Reversible Adhesion SUBSTRATUM 10

11 Biofilm Formation Flow in Fluid Phase Reversible Adhesion SUBSTRATUM 11

12 Biofilm Formation Flow in Fluid Phase Irreversible Adhesion Microcolony Growth SUBSTRATUM 12

13 Biofilm Formation Flow in Fluid Phase Biofilm Formation Bacterial Succession SUBSTRATUM 13

14 Biofilm Formation Flow in Fluid Phase ConditioningReversible Film Adhesion Irreversible Adhesion SUBSTRATUM Microcolony Biofilm Growth Formation Bacterial Succession 14

15 Biofilm Topography Stacks Mushrooms Plaque/Corrosion 15

16 Biofilm build up 1 hr 4 hrs 10 hrs 21 hrs 27 hrs 36 hrs 16

17 Heterogeniety TEM ESEM TEM 17

18 SCLM Studies - Gradients channel Plaque Surface 25 m 25 m nutrients ph Enamel Surface O2 / Eh metabolic products K+ < Na+ K+ > Na+ (Dental plaque - Wood et 18al., 2000)

19 Tooth surface Gradients - ph Heterogeneity TPEM + FLIM x - z 50 m ph 5.0 ph micro-zones mixed culture in vitro biofilm ph 7.5 Vroom et al.,

20 4 th December 2007 Properties of Biofilm

21 ecret biofilms in your water systems 21

22 Water borne microorganisms 1400 deaths per year in the USA as a result of waterborne nosocomial pneumonias due to Pseudomonas aeroginosa 4000 cases of P. aeroginosa bacteraermia in England, Wales and N Ireland per yr ~300 cases of Legionnaires disease per year ~ 500 cases of Stenotrophomonas maltophila Bioflms provide a safe haven for pathogens Immuno-compromised patents are at risk 22

23 Why are hospitals susceptible? Complex water systems with many outlets Often old buildings with old plumbing following unknown routes leading to dead-legs & blind ends Thermostatic mixer valves to control outlet temperatures PFIs tenders not specific enough, difficult to manage, hospital estates loose control Phased occupation of new buildings Highly susceptible patients to L. pneumophila, P. aeruginosa and S. maltophila 23

24 Mains supply pipes 24

25 Hot and cold water system Amplification of biofilms can occur throughout the system starting at the tank, water softener/ reverse osmosis if installed, storage water heater, pipework and finally particularly at the outlets and services 25

26 Schematic of large water system 26

27 Water storage tanks - biofilm risk factors Difficult to clean (poor design?) e.g. Difficult to remove biofilms Stagnation Areas of low or no flow, Tanks too large, Dead / blind ends, Cold Water Tanks with inlets and outlets on same side leading to short circuiting and stagnation 27

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31 Safe to wash your hands? 31

32 Do handbasins with TMVs need separate cold taps? Biofilm colonisation is likely downstream of the TMV The cold tap is not really needed and so the feed becomes a short dead leg 32

33 Modern TMVs can be incorporated into tap body to reduce lenght of dead leg x Both these taps have TMVs incorporated in them Swan necks now advised against in healthcare as they trap water The latest preferred design 33

34 Problems with newly constructed water systems New systems should be disinfected and flushed within two weeks prior to opening May be initial high bacterial counts but these should drop to close to those of incoming mains water Testing after occupation sometimes reveals continuing high heterotrophic counts Poor design Hot next to cold, inadequate insulation Radiating water systems Redundant cold taps on wash basins with TMVs on hot taps Over use of flexible components Wrong materials particularly flexible components 34

35 New water systems are safe? Hospital A Private Finance Initiative building disinfected June 2003, handed over August 2003 fully occupied by October 2003 Supposedly built to Standard Design and supposedly to UK Building and Water Fittings Regulations April 2004 Positive legionella tests followed by chlorination and negative tests July 2004 nosocomial case 1 Showers descaled and chlorinated Chlorine dioxide installed (<0.5mg/l) + extra insulation + flushing and descaling and more sampling. Deadlegs removed. No legionella positives. Managers state system now compliant with L8 35

36 New water systems are safe Hospital A part 2 March 2005 nosocomial case 2 (had been in hospital since January) died HPA grow L. pneumophila 1 from hot water matches patient isolate Further testing revealed 42% +ve (>10cfu/L) with 31% cfu/l Pasteurised, ClO 2 increased to 3mg/l, Pall point of use filters installed Findings UV on supply as it enters building Cold water at 30 C! Flexible plastic components imported from China did not comply with Water Fittings Regulations, failed BS6920 tests for ability to support microbial growth 36

37 Biofilms in lumen of flexible hoses (with kind permission of Dr T Makin) 37

38 Biofilms in lumen of flexible hoses (with kind permission of Dr T Makin) 38

39 Lumen of Water Regulations Advisory Service approved flexible hose (with kind permission of Dr T Makin) 39

40 New water systems constructed to latest regulations are safe Hospital B August 2005 Brand new 1200 bed hospital with 3 blocks. Block 1 finished early 2005 and blocks 2 and 3 still under construction to be finished and occupied in Ground floor and 2 nd floor occupied. 3 rd floors planned to be occupied soon with haematology patients. All plastic plumbing, conforms to UK Water Fittings Regulations Hot water no legionellae but cold water already colonised a few months after occupation Cause partial occupancy and therefore poor flow? Leak testing by filling with water? 40

41 Growth on different plumbing materials relative to glass (=1) (Rogers et al 1990 Applied and Environmental Microbiology) Growth relative to glass Copper Glass Heterotrophs Legionella Polybut Polyprop Polyeth Conclusion: higher flexibility of plastic generally correlates with increased support for growth upvc cpvc EPDM Latex Legionella and supporting flora were grown in continuous culture model systems. Counts are expressed as a ratio relative to the counts on glass (=1) e.g. there was approximately 10 X the growth of aerobic heterotrophs on cpvc as there was on glass. Copper most resistant ; ethylene propylene and latex most susceptible

42 Who ate all the copper? 42

43 Water Piping Regulations Water Regulations Advisory Scheme (WRAS) are concerned with products used after the time of supply Manufacturers must demonstrate that products used are WRAS approved ( Materials (non-metallic) must conform to BS 6920 appearance of the water (colour, turbidity); Promote microbial growth (MDOD test) Leach substances/metals harmful to human health into the water 43

44 Control of biofilms to medical devices dental unit water systems 44

45 C D MI DUWS Waste Water 14th September PEF TVC Sponsored by Planmeca Biofilm Clean 45

46 Controlling biofilms in dental unit water lines Comparison of TVC and % Coverage - UK lab model TVC % Cov 14th September PEF Sponsored by Planmeca Product

47 Quality of water to your washer disinfectors? 47

48 New Endoscopy suite - how good is the water quality? 48

49 Supply of pure clean water? Reverse Osmosis Systems Modern Spiral Element Irreversible biofouling on a 49 reverse osmosis

50 Different type of RO systems NEW 300L/hr 600L/hr Cold delivery with hot sanitisation 200L/hr 900L/hr Hot delivery 200L/hr 600L/hr Cold delivery 60L/hr 120L/hr cold delivery 200L/hr 600L/hr Cold delivery 50

51 Biofouling in RO units Element Deterioration 4 Membrane Deterioration 18% Fouling 77% Organic 15% Colloids 22% Scale Biofouling 43% Khedr, Desalination & Water Reuse, 10/3 (2000)

52 Consequences of Biofilms in RO Biofilm acts as secondary membrane effects: Loss of product quantity - Flux decline due to higher Δp membrane Higher energy demand if flux is to be maintained - Increase of Δp membrane and Δp feed/brine Loss of product quality (permeate) - Contamination of product Higher pretreatment and cleaning demand Possible microbial attack to membrane, glue lines and other equipment Higher replacement costs - Damage by cleaning - Damage by microbial attack Frustration and demotivation of personnel Bottom line: up to 30 % of operation costs related to biofouling! 52

53 Consequences of Biofilms in RO Biofilm acts as secondary membrane effects: Loss of product quantity - Flux decline due to higher Δp membrane Higher energy demand if flux is to be maintained - Increase of Δp membrane and Δp feed/brine Loss of product quality (permeate) - Contamination of product Higher pretreatment and cleaning demand Possible microbial attack to membrane, glue lines and other equipment Higher replacement costs - Damage by cleaning - Damage by microbial attack Frustration and demotivation of personnel Bottom line: up to 30 % of operation costs related to biofouling! 53

54 Consequences of Biofilms in RO Biofilm acts as secondary membrane effects: Loss of product quantity - Flux decline due to higher Δp membrane Higher energy demand if flux is to be maintained - Increase of Δp membrane and Δp feed/brine Loss of product quality (permeate) - Contamination of product Higher pretreatment and cleaning demand Possible microbial attack to membrane, glue lines and other equipment Higher replacement costs - Damage by cleaning - Damage by microbial attack Frustration and demotivation of personnel Bottom line: up to 30 % of operation costs related to biofouling! 54

55 Going round in circles Next problem with product or process + more Cleaner/biocide??? Problem with product or process Water samples instead of surface samples + biocide/cleaner No information on site or extent of biofouling C orgcorg C org Nutrients not limited + biocide Cleaning-unfriendly design Biomass remains as carbon source Further biofilm growth 55

56 Summary and Conclusions Water systems are not sterile Biofilm pathogens can result in infectious diseases Biofouling nutrients are potential biomass Oversupply, stagnation and nutrients will encourage biofilms Biofilm control keep biofilm formation below a threshold of infection Killing is not cleaning! Use only approved WRAS plumbing materials Actively manage your water to manage your biofilm! 56

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