 Patients will be randomized and receive their first dose of Study Drug within 24 hours of oralnasal intubation and the initiation of mechanical ventilation. The Study Period will begin with the first administration of Study Drug Study Day 1. Three mL of Study Drug 9 mg iseganan or matching placebo will be applied to all visible surfaces in the oral cavity and the oral portion of the endotracheal tube for non-tracheostomy patients every 4 hours through Study Day 14, or until the diagnosis of microbiologically-confirmed pneumonia based on central laboratory results or extubation, whichever occurs first. 