The association between colonization of the oropharynx , trachea , or stomach and predisposition to gram-negative bacillary pneumonia prompted efforts to prevent infection by using either prophylactic local application of antimicrobial agent(s) or local bacterial interference . The second method i.e. interference with alpha-hemolytic streptococci has been used successfully to prevent oropharyngeal colonization by aerobic gram-negative bacilli. The administration of antacids and H-2 blockers for prevention of stress bleeding in critically ill, postoperative, and/or mechanically ventilated patients has been associated with gastric bacterial overgrowth . Sucralfate, a cytoprotective agent that has little effect on gastric pH and may have bactericidal properties of its own, has been suggested as a potential substitute for antacids and H-2 blockers.