How many infections are caused by patient-to-patient transmission in intensive care units? - Grundmann, H; Bärwolff, S; Tami, A; Behnke, M; Schwab, F; Geffers, C; Halle, E; Göbel, UB; Schiller, R; Jonas, D; Klare, I; Weist, K; Witte, W; BeckBeilecke, K; Schumacher, M; Rüden, H; Gastmeier, P (Crit Care Med, 2005)