Welcome to the web presentation 

of the Project

HYMED

New Hygiene Services in Medical Device Cleaning and Reprocessing by the Use of

Liquid Carbon Dioxide and Extremphile Enzymes

Project HYMED (Cornet 32 EN) is a bi-national research project between Germany and Turkey funded by the Cornet programme.

Involved partners are:

FRT - European Cleaning and Hygiene Technology Research Association, DE (project coordinator)

and

the ad-hoc grouping of  companies entitled MENT - Modified Enzyme Technlologies, TR

Research work of the project is carried out by the research performers

        wfk - Cleaning Technology Research Institute, DE

and

   ITU - Istanbul Technical University, TR

Scope of HYMED

Aim of HYMED is the development of new procedures for the reprocessing of thermo-labile medical devices. Instruments such as e.g. flexible endoscopes and many others are sensitive to elevated temperatures and can only be processed at gentle temperatures below 60 °C. Within HYMED a novel one-step cleaning/disinfection procedures will be developed using highly compressed carbon dioxide (Dense Phase CO₂, DPCO₂). To improve the cleaning performance of DPCO₂ new enzyme systems are developed that boost the removal of lipids and proteinaceous soiling on instruments. Suitable enzymes have to exhibit high activity and stability within the medium DPCO₂.

Features of DPCO₂

Carbon dioxide is an atmospheric gas at concentrations of approx. 380 ppm. When compressed to 5.8 MPa (58 bar) at 20 °C a clear liquid (LCO₂) is obtained that exhibits solvent properties comparable to organic solvents. By increasing pressure and temperature above the critical conditions (T_C= 31 °C, P_C=7.3 MPa) a supercritical fluid (SCCO₂) is yielded, that shows increased solubility performance. Both, LCO₂ and SCCO₂ are commonly named Dense Phase CO₂ (DPCO₂). DPCO2 is a environmentally sound medium that is not toxic, flammable or explosive and that doesn't leave residues on the objects processed. Moreover DPCO₂ is known to exhibit antimicrobial activities.

Experimental work

Within project HYMED DPCO₂ is used as process medium for the development of a one-step cleaning/disinfection procedure for thermo-labile medical devices applying extremophile enzymes to enhance cleaning performance. 

To develop an procedure with appropriate cleaning performance, an experimental modell system consisting of metal discs soiled with sheep blood was used. Test specimens were treated with LCO₂ or SCCO₂ under addition of additives/cosolvents and particular enzymes, varying concentrations, compositions, time and other parameters. As second test system the PCDs according to appendix 8 of the guideline for flexible endoscopes (ZentralSteril 2011(5): 357-361) were used to evaluate the cleaning efficacy on geometrically complex hollow instruments.

In parallel new extremophile enzymes were developed. Therefore two fosmid gene-banks were constructed, each consisting of more than 12,000 clones containing metagenomic DNA of acidophilic and halophilic environmental microbial consortia. Screening was performed for lipases and proteases and gave three clones with interesting enzyme activities. For the investigation of enzyme activity in DPCO₂ suitable assay systems had to be developed.

For the development of the intented one-step cleaning/disinfection procedure experimental series were conducted to investigate and optimize the antimicrobial activity of DPCO₂. Stainless steel discs were soiled with sheep blood and suspended test microorganisms. As microorganisms Gram positive bacteria (e.g. E. faecium, S. aureus), Gram negative bacteria (e.g. E. coli, P. aeruginosa, K. pneumoniae and others) acid-fast bacteria (e.g. M. terrae), bacterial endospores (e.g. B. atrophaeus, B. pumilus, G. stearothermophilus), fungi (e.g. C. albicans, A. brasiliensis) and bacteriophages (e.g. MS 2) were chosen. The process challenging devices (PCD) were incubated in LCO₂ (20 °C, 5.8 MPa) or SCCO₂ (37 °C, ~8.5 MPa) with variable amounts of different additives and under varying incubation conditions to retriev relevant parameters.

Results

With regard to the intented cleaning of medical devices in DPCO₂ experimental results on the cleaning of blood soil (not denatured/denatured) in LCO₂ and SCCO₂ without application of enzymes were obtained (baseline). For the application of enzymes an increased removal of blood was demonstrated on test specisms. Applied enzymes showed a high stability towards incubation in LCO₂ and SCCO₂ with virtually no loss of enzyme activity during a 15 min incubation period. Moreover solubility of certain amino acids in DPCO₂ was demonstrated as these might be released upon enzymatic cleavage of proteins. These results were transferred to later experimental work to develop and establish a cleaning procedure for PCD's that are used as model systems for flexible endoscopes. After optimization a process was obtained that allows the cleaning of respective PCD's resulting in residual protein contents below the acceptance level given in the German guideline for the validation of automated reprocessing procedures for flexible endoscopes (Zentral Steril 2011, Supplement 3).  The procedure was also applied to other model systems (e.g. DIN ISO/TS 15883, appendix E).

Detailled information was elaborated on the influence of pressure, phase status, incubation time, additives, etc. on the antimicrobial effects towards different microorganisms. Optimized procedures applied 0.15 % and 0.35 % (w/w) of additive B and E, respectively, and resulted in a process that gave RF>5,5 within 15 min for all investigated microorganisms. Experimental results were transferred to develope a one-step procedure. Using the model system of DIN ISO/TS 15883, appendix I or appendix 9 of the German guideline it could be demonstrated that the developed procedure gives a disinfection performance in compliance with respective standards and regulations. 

 

For detailled information please contact:

Dr. Markus Wehrl

wfk-Cleaning Technology Research Institute

Campus Fichtenhain 11

Phone: ++49-2151-8210-170

Email: m.wehrl(at)wfk.de

The IGF-project 32 EN of the research association Europäische Forschungsgemeinschaft Reinigungs- und Hygienetechnologie e.V., Campus Fichtenhain 11, 47807 Krefeld, is supported via the AiF within the funding program „Industrielle Gemeinschaftsforschung und -entwicklung (IGF)“ by the Federal Ministry of Economic Affairs and Technology (BMWi) due to a decision of the German Parliament.