The upper respiratory tract of the majority of mechanically-ventilated patient is colonized with potentially pathogenic microorganisms. This was first established in a study in 1969 that reported the presence of enteric gram-negative bacteria in the oropharynx of 75 percent of critically ill patients8. A proposed explanation is bacterial overgrowth of the upper gastrointestinal tract and retrograde movement. Aspiration of secretions containing these pathogens provides a means for infection of the sterile bronchial tree. Another study published in 2007 confirmed the presence of similar pathogenic microorganisms in the lower respiratory tract of intubated patients by comparing DNA samples from bacteria on the tongue and obtained from bronchoalveolar lavage (BAL)12.