Oral bacteria, which are a source of infection for aspiration pneumonia, were examined in frail older adults with the aim of establishing a standard bacteria count that indicates the risk of pneumonia onset in this group. Methods: A survey of bacteria count in the saliva using a simple instrument for measurement of the number of oral bacteria, along with factors including swallowing function and nutritional status, was carried out in 691 elderly individuals requiring care (137 men; mean age 82.6±8.3years; 554 women; mean age 88.0±7.1years; total mean age 86.7±7.8years) at 16 nursing homes in Japan. All participants gave their consent for inclusion in the present study. During a 6-month follow-up period, participants who developed pneumonia were identified, and relationships between the factors measured at the start of the period and pneumonia onset were examined. Results: During the 6-month follow-up period, 33 participants (4.8%; 5 men, 28 women; mean age 88.3±7.4years) developed pneumonia. Pneumonia onset was significantly associated with reduced activities of daily living, swallowing dysfunction and undernourishment. Logistic regression analysis identified a saliva bacteria count of 108.5colony-forming units/mL as an independent explanatory factor for pneumonia onset (P=0.012, RR=3.759). Conclusions: Oral bacteria count of 108.5colony-forming units/mL saliva in an elderly person requiring care was identified as a risk factor for pneumonia onset. Geriatr Gerontol Int 2015; 15: 417-421.
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