The relation between tube feeding and Pseudomonas aeruginosa detection in the oral cavity.

Aspiration pneumonia is a major cause of high morbidity and mortality among elderly nursing homes residents (1). It has been reported that there is an increase in the growth of the gram-negative rod that causes pneumonia in the oral cavities of elderly patients who are bedridden (2,3). They have risk of pneumonia by repetitive aspiration of these bacteria species due to dysphagia and deterioration of the cough reflex (4–7). Tube feeding is usually used as compensatory feeding for patients with swallowing disturbance. Langmore and colleagues reported that tube feeding was a predictive factor for aspiration pneumonia (8). However, little is known about the possibility of increased oral bacteria growth resulting from receiving tube feeding in bedridden elderly persons. The aim of this study was to elucidate whether tube feeding is associated with the detection of pneumonia-causing bacterial species in the oral cavity. The subjects were 55 elderly persons (35 women and 20 men) who were long-term (longer than 2 months) residents of two nursing homes in Chiba city. All subjects had chronic diseases. Age distribution was as follows: 60–69 years: 4 (7.3%); 70–79 years: 15 (27.3%); 80–89 years: 25 (45.4%); 90 years: 11 (20.0%). Fifteen (14.2%) individuals received tube feeding. The distribution of the duration of tube feeding was as follows: 1–3 months: n 6; 4–6 months: n 5; longer than 1 year: n 4. Oral hygiene was evaluated by dentists who were able to examine the subjects with reasonable consistency using a common standard [area of dental plaque: less than half of tooth surface: 26 (47.3%); more than half of tooth surface: 29 (52.7%)]. Dental plaque on maxillary molar teeth was examined for the detection of the following bacteria species: Pseudomonas aeruginosa , Klebsiella pneumoniae , and Haemophilus parainfluenzae . Culture method was used to detect the bacteria species from samples. Logistic regression models were used to clarify the contributing factors for the detection of bacteria species. SPSS for Windows (version 9.0) was used for all statistical analyses. The detection rate of P. aeruginosa was higher than other bacteria species (Table 1). These bacteria were detected in 22 subjects. One subject was positive for both P. aeruginosa and K. pneumoniae . P. aeruginosa was detected in the oral cavity of 8 of the 15 subjects receiving tube feeding (53.3%), whereas P. aeruginosa was detected in only 3 of 40 (7.5%) subjects without tube feeding (Table 1). The risk of P. aeruginosa detection for individuals with tube feeding was nearly 20 times higher than for individuals without tube feeding (Table 1). Only tube feeding was selected as a contributing factor for P. aeruginosa detection. K. pneumoniae and H. parainfluenzae did not show significant correlation with tube feeding (Table 1). It is thought that elderly persons receiving tube feeding are more susceptible to opportunistic infection than other subjects because of lower resistance by nutrition condition. P. aeruginosa has been reported to be more capable of forming biofilm, niduses of persistent chronic infections, than other bacteria species (9–11) and to form biofilm frequently on the elastic tube (12,13). This could explain why only P. aeruginosa represented a close relation with tube feeding. Our findings suggest that elderly persons who receive tube feeding may have a higher risk of an increase in P. aeruginosa growth in the oral cavity . In our study, most of the elderly persons with tube feeding had dysphagia (14/ 15), so they were at risk of aspiration. There are several reports on the association between oral care and various infectious diseases in the elderly population (14–16). We suggest that oral care that effectively removes P. aeruginosa in the oral cavity is important for the health of elderly patients receiving tube feeding.