Oral clearance and pathogenic oropharyngeal colonization in the elderly

The elderly have an increased incidence of oropharyngeal colonization with respiratory pathogens, a well-known risk factor for the development of pneu monia. Changes in the oral milieu may occur secondary to decreased salivary production and abnormalities in swallowing. These abnormalities, common in the elderly, may result in impaired clearance of organisms, allowing patho genic colonization. To test this hypothesis, we performed a prospective cro ss-sectional analysis of 75 elderly institutionalized patients and measured oral clearance using Tc-99m-human serum albumin (HSA) administered to the oropharynx. Oropharyngeal cultures, salivary cell populations, elastase act ivity, and clinical parameters were measured simultaneously. Retention of r adiolabel ranged from 100% to 2.3% over 120 min of observation. Clearance i n the oropharynx was significantly decreased in those patients who had orop haryngeal colonization with gram-negative bacilli (GNB), Staphylococcus aur eus (SA), or yeast compared with those demonstrating normal flora by 95% co nfidence intervals. Decreased clearance was also seen in patients on antide pressants by 95% confidence levels. The absolute number of salivary lymphoc ytes/ml and buccal cells/ml was increased in colonized patients versus nonc olonized persons (mean +/- SEM, 128 X 10(3) - 49 X 10(3), 25.4 +/- 11.6 X 1 0(3)). Elastase activity was elevated in patients who had GNB compared with patients without GNB (mean SEM, 10.6 nM 5.7, versus 2.2 nM 1.2, p = 0.036) . We conclude that a decrease in salivary clearance of potentially pathogen ic organisms may be a major risk factor for the development of colonization in the elderly.