title: Primary and secondary literature should be distinguished when searching for data used in systematic reviews of nosocomial outbreaks.
authors.affiliation: 1Institute for Medical Microbiology and Hospital Epidemiology,Hannover Medical School,Hannover,Germany.
authors.forename: Ralf-Peter
authors.initials: RP
authors.lastname: Vonberg
authors.affiliation: 2Institute for Hygiene and Environmental Health,Charité - University Medicine Berlin,Berlin,Germany.
authors.forename: Petra
authors.initials: P
authors.lastname: Gastmeier
mesh_terms: D016913:Blood Component Transfusion / Q000009:adverse effects*; D003428:Cross Infection / Q000209:etiology*; D004196:Disease Outbreaks / Q000706:statistics & numerical data*; D004340:Drug Contamination / Q000706:statistics & numerical data*; D006801:Humans