Johnstone J, Muscedere J, Dionne J, Duan E, Rochwerg B, Centofanti J, Oczkowski S, Lauzier F, Marshall J, Heels-Ansdell D, Daneman N, Mehta S, Arabi Y, Zytaruk N, Dodek P, Adhikari NK, Karachi T, Charbonney E, Stelfox HT, Kristof AS, Ball I, Hand L, Fowler R, Zarychanski R, Arnaud CS, Takaoka A, Kutsogiannis J, Khwaja K, Sligl W, Loubani O, Tsang J, Lamarche D, Bowdish D, Surette M, Cook D; for the Prevention of Severe Pneumonia and Endotracheal Colonization Trial (PROSPECT) Investigators and the Canadian Critical Care Trials Group