Central Service - Issue 3/02

EDITORIAL

Science or Politics?

NEWS UPDATE

What's New in Standardisation
Operation of Steam Sterilizers
Richard-Merten Prize will not be Advertised for 2002
Cleaning, Sterilisation, Endoscope Processing - Instrument Processing at the DGKH Congress (Berlin, April 7 - 10 2002)
Quality Management in the CSSD. Report on Steri Meeting in Tuttlingen on 26 - 27 April 2002

MAIN ARTICLES

S. J. Choi*, V. Thralls, D. F. Smith:
Bacillus stearothermophilus spores (ATCC 7953) in a Hydrogen Peroxide Gas Plasma Sterilization System
(Zentr Steril 2002; 10 (3): 145-157)

Abstract
Evaluation of Inactivation Rates using both the Survivor Curve Method and MPN Method
Inactivation rates of three B. stearothermophilus spore crops were determined using both survivor curve method and MPN method in a hydrogen peroxide gas plasma sterilization system. The study was conducted in a fully loaded commercial hospital sterilizer unit. The inactivation rates of three spore crops obtained by the survivor curve method were then compared to those values obtained by the MPN method. The differences in percentage between two methods ranged from 10% to 22% for three spore crops. The study results indicated that the kill kinetics of B. stearothermophilus spores in the hydrogen peroxide gas plasma sterilization system were linear over the full range of inactivation, and no significant deviations from a linear survivor curve were noted.

D. Heider, J. Gömann*, U. Junghannß, U. Kaiser:
Kill Kinetics Study of Bacillus subtilis Spores in Ethylene Oxide Sterilisation Processes
(Zentr Steril 2002; 10 (3): 158-167)

Abstract
The kill kinetics of Bacillus subtilis spores in ethylene oxide sterilisation processes were determined, while varying the process parameters ethylene oxide concentration, relative humidity (RH), temperature and inert gas type. The experiments were carried out in an ethylene oxide resistometer in accordance with EN 866 Part 2. The D values inferred from the kill kinetics were used to determine the reaction velocity changes of the various processes conducted.

The study showed, on changing the ethylene oxide concentration from 50 to 1200 mg/l, that the reaction velocity of the process is greatly influenced by the ethylene oxide concentration and that it corresponds somewhat to a reaction of the first order kinetics across the entire concentration range. On varying the relative humidity from 10 to 100%, we found that there was a correlation between the reaction velocity in the range between 10 and 60% RH, whereas no further changes were bserved at higher levels. On varying the temperature between 30 and 64 °C, it was observed that a 10 K increase in temperature doubled the reaction velocity. On using an ethylene oxide concentration between 50 and 150 mg/l for sterilisation, no changes were observed on adding air, whereas on adding carbon dioxide the reaction velocity declined by up to 32%.

RECOMMENDATIONS

Special Guideline No. 1 - Processing Sterile Medical Devices
Recommendation of the French Ministry of Health

MAILBOX

Copper Fixation Plate

RECOMMENDATIONS BY THE QUALITY TASK GROUP (AK »QUALITÄT«)

Classifying Medical Devices before Processing (Part 1)