Backgrounds: It remains unclear if antibiotics should be used for the treatment of acute aspiration bronchitis to prevent the development of pneumonia. This study aimed to assess the associations between the use of antibiotics and the development of pneumonia among patients with acute aspiration bronchitis. Methods: We retrospectively reviewed consecutive patients with acute aspiration bronchitis aged ≥75 years. Acute aspiration bronchitis was defined as a condition with aspiration risk, high fever (body temperature, ≥37.5 °C), respiratory symptoms, and the absence of evidence of pneumonia. Results: There was no significant difference in the incidence of pneumonia between patients treated with and without antibiotics for acute aspiration bronchitis (6/44, 14% vs. 31/143, 22%; p = 0.242). Lower estimated glomerular filtration rate (adjusted odds ratio, 0.956; 95% confidence interval, 0.920–0.993) was significantly associated with the development of pneumonia. Conclusions: Antibiotic administration should not be routinely recommended to prevent pneumonia following acute aspiration bronchitis, and patients with decreased renal function should be closely monitored. A randomized controlled trial is necessary to validate these results.

Although Klebsiella pneumoniae pneumonia is an insidious threat among the elderly, the role of radiological features has not been elucidated. We aimed to evaluate thin-section chest computed tomography (CT) features and assess its associations with disease prognosis in elderly patients with acute K. pneumoniae pneumonia. We retrospectively included elderly patients, admitted for acute K. pneumoniae pneumonia, and investigated thin-section CT findings to determine whether bronchopneumonia or lobar pneumonia was present. The association between the radiological pattern of pneumonia and in-hospital mortality was analyzed. Eighty-six patients with acute K. pneumoniae pneumonia were included, and among them, the bronchopneumonia pattern was observed in 70 (81%) patients. Twenty-five (29%) patients died in hospital, and they had a greater incidence of lobar pneumonia pattern (40% in nonsurvivors vs 10% in survivors; P = .008), low albumin level (2.7 g/dL, range, 1.6–3.8 in nonsurvivors vs 3.0 g/dL, range, 1.7–4.2 in survivors; P = .026) and higher levels of aspartate aminotransferase (30 U/L, range, 11–186 in nonsurvivors vs 23 U/L, range, 11–102 in survivors, P = .017) and C-reactive protein (8.0 mg/dL, range, 0.9–26.5 in nonsurvivors vs 4.7 mg/dL, range, 0.0–24.0 in survivors; P = .047) on admission. Multivariate analysis showed that lobar pneumonia pattern was independently associated with increased in-hospital mortality (adjusted hazard ratio, 3.906; 95% CI, 1.513–10.079; P = .005). In elderly patients with acute K. pneumoniae pneumonia, the lobar pneumonia pattern may be less commonly observed, and this pattern could relate to poor prognosis.