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Central Service - Issue 3/2003

Central Service - Issue 3/2003


Sterilisation and the Truth


  • What's New in Standardisation: Basic Discussion of Small Sterilizers
  • Processing in the Spotlight at the 4th Hygiene Dreiländer Congress in Friedrichshafen, 25 - 26 March 2003
  • UK Central Sterilising Club Scientific Meeting
  • Study Afternoon VSZ 20 March 2003, UI Antwerp
  • British Authorities Warn Against Processing Single-Use Medical Devices


T.J.H. Orzechowski, A.C.P. de Bruijn, C. Wassenaar:
Validation of a Cleaning Test for Flexible Endoscopes
(Zentr Steril 2003; 11 (3): 165-178)

Technological advances in the past 30 years have resulted in the development of complex, expensive and heat sensitive flexible endoscopes. Because of the design complexity and the region of the body where they are used, endoscopes present special challenges to cleaning. If the instruments are not properly cleaned the disinfection or sterilisation procedure can fail and increase the possibility of infection transmission from one patient to another.
Hospital visitations of the Dutch Health Care Inspectorate in 1999 showed that the cleaning and disinfection procedures in endoscopy departments are neither completely validated nor embedded in a quality system. One reason that insufficient attention was paid to the validation of the cleaning process was the lack of a standard validation test for measuring cleaning efficiency. A test to establish the efficacy of the cleaning stage in a reprocessing procedure needs to be simple and easy to perform in hospital practice. The test must show the parts which are difficult to clean and should enable optimisation of critical parameters (such as precleaning, washing time, washing temperature, flow through the channels). This article describes a test, using a surrogate device to mimic the channel system and valves of a basic flexible endoscope. In the test the lumens of the surrogate device were soiled with a mixture of blood proteins and mucus, which served as a model for practical conditions.
Tests showed that preparation, application and verification of the test soil needed a thorough validation. Application of the method in 18 Dutch hospitals proved the method to be feasible and showed that it was able to discriminate between different washing procedures such as those using a precleaning step and warm or cold cleaning processes.
This method allows optimisation of critical parameters for each individual washing process, for instance, after maintenance or installation of the washing machine or after a defect has been fixed.

N. Shetty, J. Holton, J.B. Selkon:
Microbicidal and In-Use Activity of Sterilox: An Effective and Safe Alternative to Glutaraldehyde for Use in Endoscopy Units
(Zentr Steril 2003; 11 (3): 179-191)

Rapid and reliable washing and disinfection of flexible, fibre-optic endoscopes and other heat sensitive instruments is an essential pre-requisite in a busy endoscopy unit. Thorough, manual cleaning followed by immersion in 2% glutaraldehyde or the use of automatic washer/disinfectors is widely practiced in many hospitals. Exposure to glutaraldehyde fumes is known to cause asthma and dermatitis in health care staff. The Advisory Committee on Toxic Substances of the Health and Safety Commission, UK, has stipulated a Maximum Exposure Limit (MEL) of 0.02 ppm as a weighted average over a period of 8 hours for glutaraldehyde. Endoscopy units are therefore required to install expensive ventilation and air extraction systems to protect their staff. Furthermore, contact times of 10 minutes for routine disinfection and 20 minutes for high level disinfection have been recommended for 2% glutaraldehyde by the British Thoracic Society and the British Society for Gastroenterology. Longer exposure times of 60-95 minutes have been proposed for elimination of Mycobacterium avium intracellulare.
Alternative disinfectants such as peracetic acid and chlorine dioxide have been successfully evaluated. Peracetic acid is expensive and tarnishes metal components of the endoscope and erodes components of the washer/disinfector apparatus, necessitating modification of the machine. It is also less stable than glutaraldehyde requiring change of solution every 24 hours. Chlorine dioxide based disinfectants have similar disadvantages.
These constraints have strained the resources of endoscopy units that need rapid turn around of endoscope cleaning and disinfection for use between patients. This paper describes the microbicidal and in-use activity of Sterilox, against a range of organisms. Peracetic acid and 2% glutaraldehyde were included as comparison. Sterilox achieved >5log10 kill with 5% horse serum (HS) in 2 minutes against Ps. aeruginosa, vancomycin resistant Enterococcus species, E. coli, S. aureus, Mycobacterium tuberculosis, and four atypical Mycobacterium species: M. avium, chelonei, xenopi and smegmatis. Sporicidal activity (Clostridium difficile, Bacillus subtilis var. niger) was diminished in the presence of 5% HS. Increasing the volume of Sterilox, achieved >5log10 kill in the presence of 1% HS. Sterilox, was virucidal in 2 minutes against HIV, poliomyelitis virus type 2 and duck embryo hepatitis B virus in the presence of 1% HS. There was rapid loss of viability of Cryptosporidium parvum (90% in 30 minutes) by dye exclusion. In-use tests with automated endoscope washer/disinfector apparatus showed microbicidal activity within 2 minutes, when endocscopes were thoroughly pre-cleaned. Sterilox may be an effective alternative in endoscopy units; it is non-corrosive and non-toxic to biological tissues.


P. Hooper:
Purchase of Instruments - Use of Loan Instruments


Water Provision for Steam Generation in Steam Sterilisation


Daily Check of Washer-Disinfectors Before Placing Them in Operation

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