1. 1Institut für Angewandte Mikrobiologie, Universität Giessen, Giessen, Germany
2. 2Wahnbachtalsperrenverband Siegelsknippen, Siegburg, Germany
3. 3Institute for Hygiene and Public Health, University Hospital Bonn, Germany
4. 4Institute for Medical Microbiology, Justus-Liebig University Giessen, German Centre for Infection Research Site Giessen-Marburg-Langen, Giessen, Germany