A pathogen was identified in 140 (55%) patients in this study, in accordance with detection rates in other studies ranging from 38 to 82% [4, 12, 17, 19, 20, 22, 29–35]. A mixed bacterial-viral etiology was found in 11 (8%) patients. Previously described rates varied between 2 and 23% [17, 19, 22, 29–35]. Some studies suggested that mixed bacterial-viral infections result in more severe clinical diseases (as measured by the CURB-65 score or the pneumonia severity index) [17, 34], a higher rate of mechanical ventilation, longer duration of ICU care [36, 37], longer hospital stays [22, 36], or higher mortality [37, 38], while other studies did not [29, 39, 40]. In this study, mixed bacterial-viral infections were associated with a higher rate of ICU admission and mechanical ventilation compared to pure viral (p = 0.05; p = 0.005) and pure bacterial (p = 0.06; p = 0.19) infections if all patients were considered. However, these results should not be viewed as representative of the etiology of lower RTI in East Switzerland as these hospitals presented a preselected group of patients.