Clinical manifestations and risk factors of community-onset Acinetobacter species pneumonia in Japan; case control study in a single institute in Japan.

To clarify the etiology, patients' characteristics and risk factors for community-onset AP (Acinetobacter species pneumonia), we conducted this case-control study. We reviewed all patients with community-onset AP at our institute from 2010 until 2018. We defined non-AP group as a control. The patients with non-Acinetobacter spp. pneumonia (non-AP) were randomly selected during the study period without clinical information based on medical records' list among patients with community-onset pneumonia. The age (±2 years) and sex were matched to the patients with community-onset AP, and the ratio was AP:non-AP group = 1:3. Patients' characteristics, clinical outcomes, pathogens isolated and drug susceptibility were evaluated by comparing AP and non-AP group. The mean age of community-onset AP group was 79 years. They were 8 males and 5 females. The 30-day and in-hospital mortality rates of community-onset AP were 23% (v.s. 3%, p = 0.049) and 31% (v.s. 5%, p = 0.029) respectively, which are higher than the control group. Heavy alcohol consumption (23% v.v. 0%, p = 0.023), higher Charlson Comorbidity index (3.2 v.s. 2.0, p = 0.046) and lobar pneumonia by chest radiology (50% v.s. 23%, p = 0.071) were seen more frequently in community-onset AP than in the control group. In conclusion, community-onset AP shows poor outcomes despite the appropriate antibiotic therapy. Heavy alcohol history might be a risk factor of AP. Patients with community-onset AP could have more comorbidity and poor general conditions than the control group.