75% negative skin test results in patients with suspected hypersensitivity to beta-lactam antibiotics: Influencing factors and interpretation of test results oleh Lukas Joerg, MD, Susann Hasler, MD, Anna Gschwend, PhD, Cordula Meincke, MD, Thierry M. Nordmann, PhD, Martin Glatz, MD, Michelle Heilig, BSc, Benno Schnyder, MD, Arthur Helbling, MD, Peter Schmid-Grendelmeier, MD