Disinfectant efficacy testing for bacterial endospores against hydrogen peroxide


Head of Microbiology, Bio Products Laboratory, Elstree, United Kingdom


Effective cleaning and disinfection of pharmaceutical and healthcare facilities requires effective practices and appropriate biocides. Application is typically through the use of two biocides in rotation. The expectation is that one disinfectant is sporicidal, not least because the presence of spore-forming bacteria poses a contamination risk due to the ability of these organisms to survive harsh environmental conditions. An example sporicide is hydrogen peroxide. It is incumbent upon each user to assess the selected sporicide for efficacy; however, developing a suitable test is not straightforward. This paper provides an approach that can be adopted for developing a sporicidal efficacy test against bacterial endospores, using hydrogen peroxide as the test sporicidal disinfectant.


The selection of disinfectants is based on a series of factors, relating to format, safety, and stability. The most important factor, however, is efficacy. While manufacturer’s data will provide an indication of performance and effectiveness, an assessment of efficacy, of microcidal kill, should be based on laboratory testing.

Efficacy is demonstrated through performance testing to show that the disinfectant is capable of reducing the microbial bioburden in either suspension (planktonic state) or from cleanroom surfaces to an acceptable level.
The disinfectant efficacy validation should provide documented evidence that the disinfectant demonstrates bactericidal, fungicidal, and/or sporicidal activity necessary to control microbial contamination in the facility.

Regulatory agencies expected the users of disinfectants within cleanrooms to evaluate the efficacy of disinfectants. Various standards are available to guide the microbiologist through this process. What is more difficult is the content of some of the standards thems ...