1. Newborn Research, Department of Neonatology, University Hospital and University of Zurich , Zurich , Switzerland
2. Kantonsspital Baden, Department of Pediatrics and Adolescents , Baden , Switzerland
3. Medica (Medizinische Laboratorien Dr. F. Kaeppeli AG) , Zurich , Switzerland
4. Institute of Medical Microbiology, University of Zurich , Zurich , Switzerland