Saliva secretion and oral flora in prolonged nasogastric tube-fed elderly patients

Background: In a previous study we showed that prolonged nasogastric tube feeding is associated with pathogenic oral flora. Objective: To reexamine the impact of prolonged nasogastric tube feeding on the oral microbiota and to explore the salivary flow and composition in elderly patients in long-term care. Methods: We compared a group of elderly patients fed by nasogastric tube with a control group of elderly patients in long-term care who are fed orally. Bacteriotogic studies were performed by culturing samples from the oropharynx. Saliva studies included quantitative and biochemical analysis of basal and stimulated salivary flow. Results: Bacteriotogic studies performed in 90 patients revealed a significantly higher prevalence of gram-negative bacteria In nasogastric tube-fed patients (73% vs. 13%, P < 0.001). It is emphasized that Pseudomonas aeruginosa and Klebsiella pneumoniae were commonly and exclusively isolated from the oral flora of the nasogastric tube-fed patients (P < 0.001, P < 0.05). In the saliva studies performed on 23 nasogastric tube-fed and 21 control patients, basal and stimulated salivary flow was not significantly different in the two groups, however the ratio of stimulated to basal flow was reduced in the nasogastric tube-fed group (P < 0.05). Significant differences were also found in the concentrations of sodium, amylase, phosphor and magnesium. Noteworthy was the concentration of uric acid, the main non-enzymatic antioxidant of saliva, which was significantly lower in nasogastric-tube fed patients (P < 0.002). Conclusions: These findings suggest that prolonged nasogastric tube feeding is associated with pathologic colonization of the oropharynx and with alterations in the saliva that are related to the risk of aspiration pneumonia. Further research is called for, as well as a thorough revision of the existing oral cleansing procedures in these patients.