Risk factors for initial antibiotic treatment failure in patients with aspiration pneumonia

Sulbactam/ampicillin （SBT/ABPC） and ceftriaxone （CTRX） are the initial antibiotics recommended for treating aspiration pneumonia without risk factors for drug-resistant pathogens. However, the condition of some patients does not improve with these antibiotics. Therefore, we investigated the new risk factors associated with failure of initial antibiotic treatment in patients with aspiration pneumonia. This study included 487 patients diagnosed with aspiration pneumonia who received initial antibiotic treatment with SBT/ABPC or CTRX, and were hospitalized at the Respiratory Medicine Department of the Yokohama City Minato Red Cross Hospital. The outcome was initial antibiotic treatment failure, which was defined as a change from initial to secondary antibiotic treatment. The characteristics of patients with and without antibiotic treatment failure were compared using univariate analyses, and significant independent risk factors for the initial antibiotic treatment failure were selected using multivariate analyses. The mean age of the patients was 84.1 ± 9.6 years; 302 （62％） of them were men and 93 patients experienced antibiotic treatment failure. Logistic regression analysis extracted no restriction of diet on admission （odds ratio ［OR］, 3.23; 95% confidence interval ［CI］, 1.35-7.74）, history of hospitalization due to aspiration pneumonia （OR, 1.81; 95％CI, 1.12-2.93）, the severity of pneumonia （OR, 1.37; 95％CI, 1.01-1.86）, and C-reactive protein （CRP） level （OR, 1.26; 95％CI, 1.09-1.45） as risk factors for initial antibiotic treatment failure. Our results suggested that no restriction of diet on admission, history of hospitalization due to aspiration pneumonia, severity of pneumonia, and increased CRP levels were the risk factors associated with failure of initial antibiotic treatment in patients with aspiration pneumonia. These factors will be useful for determining an effective initial treatment strategy for patients with aspiration pneumonia.