Evaluation of the Recovery Rate of Different Swabs for Microbial Environmental Monitoring.

Abstract

Environmental microbiological monitoring provides information on the hygiene condition of pharmaceutical clean rooms and equipment for manufacturing of drug products. Different methods can be used to recover microorganisms. For surfaces, normally contact plates (e.g., RODAC or dipslides) are used; however, when surfaces are uneven, swabs should be used. In the present study three different swabs were evaluated for their ability to recover microorganisms from different surfaces. Thereby two methods and two approaches were evaluated. Swab samples were either directly stroked on agar or the swab was eluted, membrane-filtrated, and the filter placed on an agar plate. Experimentally, artificial inoculated surfaces typically found in clean rooms (in vitro study) and naturally inoculated floors (in situ study) were sampled. Thus with this approach the most convenient swab and the most suitable recovery methods under laboratory as well as real clean room conditions were evaluated. With this set-up, we found the most suitable swab for our environmental monitoring not only by using artificial inoculated surfaces but also under more realistic clean room conditions, which is most important for microbiological environmental monitoring sampling.