Dunkelberg Hartmut, Rohmann Susanne
Medical Institute of General Hygiene and Environmental Health, University of Goettingen, Wundausweg 2, D-37073 Goettingen, Germany.
Infect Control Hosp Epidemiol. 2006 Apr;27(4):367-71. doi: 10.1086/503345. Epub 2006 Mar 29.
We developed a microbiological test to detect the penetration of airborne microorganisms through the packaging of medical products after sterilization, to meet the requirements of European standard EN 556. We applied this test method to transparent pouches.
The microbial-barrier properties of the transparent pouches were determined using the microbial challenge test, in which the package was placed inside an exposure chamber and exposed to a defined aerosol of Saccharomyces cerevisiae. The atmospheric pressure in the chamber was periodically reduced by 0-75 millibars, to simulate weather-dependent pressure changes. Thermoresistant petri dishes filled with nutrient agar were integrated into the transparent pouches before sterilization. The packages were incubated after exposure. They were then opened and examined for colony growth.
The number of recontaminated packages per test group (n=50) depended on the microbial bioload (defined as the number of colony-forming units per plate) to which the packages were exposed and on the size and number of decreases in atmospheric pressure. Results of multiple regression analysis showed a significant increase in the number of recontaminated packages in correlation with the product of the values for microbial bioload and the size and number of decreases in atmospheric pressure. When we analyzed the probability of recontamination of wrapped medical devices after 2 reductions in atmospheric pressure (30 millibars each) and with a surface microbial load of 10 colony-forming units per 64 cm(2), we estimated that the frequency of recontamination was 1 : 100,000.
Multiple regression analysis showed that the proposed microbial challenge test is suitable to determine the probability of package recontamination at the 1 : 1,000,000 level.
我们开发了一种微生物检测方法，用于检测空气传播的微生物在医疗产品灭菌后透过包装的情况，以满足欧洲标准EN 556的要求。我们将此检测方法应用于透明包装袋。
使用微生物挑战试验来测定透明包装袋的微生物屏障性能，即将包装置于暴露舱内，使其暴露于规定的酿酒酵母气溶胶中。定期将舱内气压降低0 - 75毫巴，以模拟与天气相关的气压变化。在灭菌前将装有营养琼脂的耐热培养皿放入透明包装袋中。暴露后对包装进行培养。然后打开包装检查菌落生长情况。
每个试验组（n = 50）中再次污染的包装数量取决于包装所暴露的微生物生物负荷（定义为每平板的菌落形成单位数量）以及气压降低的幅度和次数。多元回归分析结果表明，再次污染的包装数量与微生物生物负荷值以及气压降低幅度和次数的乘积呈显著正相关。当我们分析在气压降低两次（每次30毫巴）且表面微生物负荷为每64平方厘米10个菌落形成单位的情况下，包装医疗设备再次污染的概率时，估计再次污染的频率为1 : 100,000。
多元回归分析表明，所提出的微生物挑战试验适用于在1 : 1,000,000水平上确定包装再次污染的概率。
