Fig. 1

Time trends of exposed patient days and treatment days by age group, and percentage of elderly patients in the ICU cohort. Proportion of patients aged ≥80 years from a German 26-bed surgical ICU based on 17,464 admissions from April 2006 to October 2013. Antibacterial treatment trends are reflected by the fraction of therapy days (sum of different classes of which antibacterial agents were administered in a day) per 100 patient days and exposed patient days (days of ICU stay in which at least one antibacterial agent irrespective of the class was administered) per 100 patient days