Black Elaine, Owens Krista, Staub Richard, Li Junzhong, Mills Kristen, Valenstein Justin, Hilgren John
Ecolab Research, Development and Engineering Center, Eagan, Minnesota, United States of America.
PLoS One. 2017 Oct 24;12(10):e0187074. doi: 10.1371/journal.pone.0187074. eCollection 2017.
Disinfectants play an important role in controlling microbial contamination on hard surfaces in hospitals. The effectiveness of disinfectants in real life can be predicted by laboratory tests that measure killing of microbes on carriers. The modified Quantitative Disk Carrier Test (QCT-2) is a standard laboratory method that employs American Iron and Steel Institute (AISI) Type 430 stainless steel carriers to measure hospital disinfectant efficacy against Clostridium difficile spores. The formation of a rust-colored precipitate was observed on Type 430 carriers when testing a peracetic acid (PAA)-based disinfectant with the QCT-2 method. It was hypothesized that the precipitate was indicative of corrosion of the Type 430 carrier, and that corrosion could impact efficacy results. The objective of this study was to compare the suitability of AISI Type 430 to Type 304 stainless steel carriers for evaluating PAA-based disinfectants using the QCT-2 method. Type 304 is more corrosion-resistant than Type 430, is ubiquitous in healthcare environments, and is used in other standard methods. Suitability of the carriers was evaluated by comparing their impacts on efficacy results and PAA degradation rates. In efficacy tests with 1376 ppm PAA, reductions of C. difficile spores after 5, 7 and 10 minutes on Type 430 carriers were at least about 1.5 log10 lower than reductions on Type 304 carriers. In conditions simulating a QCT-2 test, PAA concentration with Type 430 carriers was reduced by approximately 80% in 10 minutes, whereas PAA concentration in the presence of Type 304 carriers remained stable. Elemental analyses of residues on each carrier type after efficacy testing were indicative of corrosion on the Type 430 carrier. Use of Type 430 stainless steel carriers for measuring the efficacy of PAA-based disinfectants should be avoided as it can lead to an underestimation of real life sporicidal efficacy. Type 304 stainless steel carriers are recommended as a suitable alternative.
消毒剂在控制医院硬质表面的微生物污染方面发挥着重要作用。消毒剂在现实生活中的有效性可通过测量载体上微生物杀灭情况的实验室测试来预测。改良的定量盘式载体试验（QCT - 2）是一种标准实验室方法，它采用美国钢铁协会（AISI）430型不锈钢载体来测量医院消毒剂对艰难梭菌孢子的效力。在用QCT - 2方法测试一种基于过氧乙酸（PAA）的消毒剂时，在430型载体上观察到形成了锈色沉淀。据推测，该沉淀表明430型载体发生了腐蚀，并且腐蚀可能会影响效力结果。本研究的目的是比较使用QCT - 2方法时，AISI 430型不锈钢载体与304型不锈钢载体对评估基于PAA的消毒剂的适用性。304型比430型更耐腐蚀，在医疗环境中普遍存在，并且用于其他标准方法。通过比较载体对效力结果和PAA降解率的影响来评估载体的适用性。在使用1376 ppm PAA的效力测试中，在430型载体上5分钟、7分钟和10分钟后艰难梭菌孢子的减少量比在304型载体上的减少量至少低约1.5个对数10。在模拟QCT - 2测试的条件下，430型载体存在时PAA浓度在10分钟内降低了约80%，而在304型载体存在时PAA浓度保持稳定。效力测试后对每种载体类型上的残留物进行元素分析表明430型载体发生了腐蚀。应避免使用430型不锈钢载体来测量基于PAA的消毒剂的效力，因为这可能导致对实际生活中杀孢子效力的低估。推荐使用304型不锈钢载体作为合适的替代品。
