wfhss and das conference 2013 - session a-3: potential ......wfhss and das conference 2013 - session...

Potential of Cold Atmospheric Plasma as a new method for the decontamination and

sterilization of reusable surgical instruments.

14th World Sterilization Congress8th National Sterilization Disinfection Congress of Turkey

6th-9th November 2013

Rodolphe Hervé PhD, MSc

The five main functions performed in a hospital sterile service department

Standard reprocessing

Decontamination and sterilization

Assessment of instruments cleanliness

a

d

b c

e f

Thioflavin T (bright blue) and SYPRO Ruby (amber) dual staining observed on (a-e) a suction canullae and (f) diathermy forceps from a neurosurgery set that were fully reprocessed through a sterile service department. White bars are 100 μm, red bar is 10 μm.

Standard reprocessing: neurosurgery instruments

Hervé et al., JHI 2010

Proteinaceous (total and amyloid) contamination on a succion cannulae isolated from a craniotomy set.

Standard reprocessing: neurosurgery instruments

Standard reprocessing: flexible luminal endoscopes

Hervé et al., JHI 2012

Standard reprocessing: endodontic files

Standard reprocessing: endodontic files

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ng/m

m2

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Control Cleaner 1 Cleaner 2 Cleaner 3 Cleaner 4

Treatment

ng/m

m2

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Hervé et al., JHI 2010

Cleaning limitationsProtein removal action of various cleaners

Cleaning limitations

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Control Cleaner 1 Cleaner 2 Cleaner 3 Cleaner 4

Treatment

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yloi

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Remaining contamination on surfaces(proportion of hydrophobic amyloid-rich proteins)

Hervé et al., JHI 2010

Mechanism

Physical disruption (detergent, sonication, brushing, flushing)

Enzymatic degradation

Chemical modification (pH>12)

Potential caveats

Displacement and/or spreading

Shelf life; control of parameters

Damage to instruments; control of parameters and efficacy

How can standard cleaning fail ?

What is gas plasma?

BenefitsBenefits

• Energetic electrons à chemical dissociation @ low gas temperature

• On-site production of reactive, short-living species e.g. O2

•–; O; 1O2; NO … OH• and H2O2à known to act

on protein, lipid and DNA

• Oxidants: OH•, O2•–; O; 1O2, H2O2

Non-equilibrium Chemistry

Kong MG et al (2009) New J. Phys. 11: 115012; Iza F et al (2008) Plasma Process. Polym. 5(4): 32.

what is gas plasma?| Shooting Plasma

Nan

osec

ond

imag

ing

Exposure: 1nsInterval: 100 ns

CAP endo-decon| Electron Bombardment

Walsh JL and Kong MG (2008) Appl. Phys. Lett. 94: 021501;

Testing of first CAP prototype

High purity helium/oxygen mix

CAP parameters during initial tests

5 L/min and 100 ml/min respectively

Target surface set within 1.5 cm

Up to 2 min application

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reference 30 sec 60 sec 90 sec 2 min 2+1 min 2+2 min

Treatment duration

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Testing of first CAP prototype

Spiked implant wires before CAP treatment

Spiked implant wires after partial CAP treatment

CAP appears equally effective againstamyloid proteins

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1000015000200002500030000350004000045000

control CAP-treated

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idua

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inat

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(pix

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ield

of v

iew

)

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yloid / total protein ratio (%)

Total protein Prion amyloid amyloid proportion (%)

CAP endoDecon| Versatility and Uniformity Control

Cao Z et al (2009) Appl. Phys. Lett. 94: 021501; Nie Q et al (2009) New J. Phys. 11: 115015; Kong MG (2011) J. Phys. D: Appl. Phys. 44(17): 174018; Walsh JL et al (2008) IEEE Trans. Plasma Sci. 36(4): 1314.

CAP

The place of CAP in standard reprocessing

CAP

The place of CAP in standard reprocessing

CAP

The place of CAP in standard reprocessing

Dentistry clinics; Endoscopy Units

what is gas plasma?| OptimisationAr-O2-H2O Plasmas

• up to 1,000 chemical reactions• threshold dose of each protein-inactivating plasma agent is unknown

• complication with synergy• plasma diagnostics is complex and not always accessible

• plasma diagnostics in liquid phase – very under-studied field• if achieved, a knowledge-based inaction – indirect inactivation marker

• … empirical strategy – unreliable for ensuring efficacy and for system scalingAgents Plasma Characterisation

O*; OH* etc Excited species – Optical emission spectroscopy(OES)

O, H2O-clusters Ground state – OES not good – MBMS

OH, H2O2 etc in H2O Electron spin resonance (ESR) spectroscopy

UV Absolute OES

Ozone Spatial resolved – UV absorption spectroscopy (UVAS)

Electron density Probes not applicable – current density

Electron energy Boltzmann plot

All Plasma modelling

… additional studies, such as OH scavengers

CAP optimisation

EDIC/EF for rapid and very sensitive quantification of residual proteins and microorganisms.

Refined prion infectivity assays for human strains under development.

Mechanisation and scaling up of the process.

Adaptation into SSDs.

Proteinaceous microcontamination (potentially including PrPSc in affected countries) is a common problem in clinical settings.

Conclusions

Current standard decontamination procedures suffer from inherent physicochemical limitations.

CAP offers a radically different decontamination mechanism capable of targeting individual atoms, without the problems associated with liquid solutions.

Further development required to adapt the technology to different end users/instruments.

SSDs (England)

Acknowledgements

English Department of Health

The Pirbright Institute

NCJDSU (Edinburgh)

CEA (France)

Public Health England

Fondation Alliance BioSecure

Thank you!

R.Herve@soton.ac.uk

mkong@odu.edu C.W.Keevil@soton.ac.uk