The role of salivary function on oropharyngeal colonization.

Aspiration of oropharyngeal flora is the most common route of acquiring Gram-negative pneumonia, a major nosocomial infection. Epidemiologic studies indicate that the elderly are at increased risk for developing these life-threatening pneumonias. The primary objective of this study was to determine the effects of salivary oral defenses against Gram-negative colonization. The study population consisted of 41 male outpatients, age 70 and older, seen at the Denver VAMC. The group included subjects with both diminished and normal salivary flow. Each subject answered a questionnaire regarding overall health, medication use, and symptoms of salivary dysfunction. We then collected whole saliva, unstimulated and stimulated parotid saliva, and performed a throat swab on each patient. For each throat culture, analysis was done to identify Gram-negative bacteria. Flow rates between colonized (n = 6) and noncolonized subjects (n = 34) were compared. While there were no significant differences in the flow rates between the two groups, a trend was noticed in that flow rates were lower for all three flow measures in the colonized group (whole, 22% decrease; unstimulated, 22% decrease; and stimulated, 28% decrease). These preliminary findings suggest that subjects with diminished salivary flow may possibly be at increased risk for oropharyngeal Gram-negative colonization. Research on the role that saliva plays in oropharyngeal bacterial colonization is continuing.