Of the 254 patients in the cohort, 61 (24%) received antibiotics before hospitalization, and 149 (59%) of all in- and outpatients received antibiotics at the time of rtPCR testing. Of 80 patients with a viral etiology, 59 (74%) received antibiotics at any time point, 28 of 40 children (70%) and 31 of 40 adults (78%). Inpatients with a bacterial etiology were treated with antibiotics in 92% (p = 0.09) and longer than those with a viral etiology or no pathogen (p = 0.02; p = 0.01). If children and adults were analyzed individually, similar but non-significant trends were observed (Tables 5, 6 and 7).Table 5Outcome depending on relevant detected pathogen for adult patients Viral Bacterial Mixed No pathogen p-value a (n = 40) (n = 36) (n = 6) (n = 100) Viral vs. bacterial Viral vs. mixed Viral vs. no pathogen LOS inpatients, median days (IQR)8 (6–21)21 (13–35)11.5 (5–44.25)15 (8–23.5)<0.0010.670.03 Complications, n (%) ICU admission11 (27.5)13 (36.1)3 (50.0)24 (24.0)0.420.510.67 Mechanical ventilation6 (15.0)11 (30.6)3 (50.0)19 (19.0)0.110.160.58 ARDS3 (7.5)5 (13.9)2 (33.3)6 (6.0)0.600.241.00 Sepsis24 (60.0)24 (66.7)5 (83.3)6 (6.0)b 0.550.53n/a Mortality (all cause)4 (10.0)4 (11.1)1 (16.7)6 (6.0)1.001.000.62 Antibiotic use (any indication) Any inpatient antibiotics, n (%)30/35 (85.7)29/32 (90.6)4/6 (66.7)72/89 (80.9)0.810.540.53 Duration of inpatient use, mean days ± SD (range)12.5 ± 14.3 (0–63)18.1 ± 16.0 (0–72)10.3 ± 12.1 (0–31)10.8 ± 11.4 (0–63)0.140.730.49 Discharged receiving oral antibiotics, n (%)11 (30.6)c 17 (53.1)d 1 (20.0)e 23 (24.5)f 0.061.000.48 ARDS acute respiratory distress syndrome, ICU intensive care unit, IQR interquartile range, LOS length of stay, n number, SD standard deviation aFor continuous variables, 2-sample independent t-test or Mann-Whitney-U-test were used. For categorical variables, Mantel-Haenszel chi square or Fisher exact test were used bSepsis requires a pathogen per definition. In these six cases sepsis was exceptionally defined according to discharge papersMissing values due to death or ongoing hospitalisation at time of analysis (number): c4; d4; e1; f6. For calculation of percentage and p-value missing values were excluded Table 6Outcome depending on relevant detected pathogen for pediatric patients Viral Bacterial Mixed No pathogen p-value a (n = 40) (n = 6) (n = 5) (n = 21) Viral vs. bacterial Viral vs. mixed Viral vs. no pathogen LOS inpatients, median days (IQR)18.5 (6–48.75)47.5 (14–95.75)34 (17.5–201.5)37 (8–70)0.190.100.45 Complications, n (%) ICU admission18 (45.0)4 (66.7)5 (100.0)12 (57.1)0.580.060.37 Mechanical ventilation8 (20.0)4 (66.7)4 (80.0)11 (52.4)0.070.030.01 ARDS1 (2.5)0 (0.0)1 (20.0)0 (0.0)1.000.421.00 Sepsis17 (42.5)4 (66.7)2 (40.0)0 (0.0)0.501.00n/a Mortality (all cause)2 (5.0)0 (0.0)0 (0.0)0 (0.0)1.001.000.85 Antibiotic use (any indication) Any inpatient antibiotics, n (%)28/38 (73.7)6/6 (100.0)5/5 (100.0)18/20 (90.0)0.380.490.26 Duration of inpatient use, mean days ± SD (range)8.6 ± 13.4 (0–73)14.2 ± 11.0 (0–34)13.8 ± 7.8 (7–24)6.2 ± 4.8 (0–18)0.340.400.33 Discharged receiving oral antibiotics, n (%)6 (15.8)b 0 (0.0)1 (20.0)3 (15.0)c 0.781.001.00 ARDS acute respiratory distress syndrome, ICU intensive care unit, IQR interquartile range, LOS length of stay, n number, SD standard deviation aFor continuous variables, 2-sample independent t-test or Mann-Whitney-U-test were used. For categorical variables, Mantel-Haenszel chi square or Fisher exact test were usedMissing values due to death or ongoing hospitalisation at time of analysis (number): b2; c1. For calculation of percentage and p-value missing values were excluded Table 7Outcome depending on relevant detected pathogen for all patients Viral Bacterial Mixed No pathogen p-value a (n = 80) (n = 42) (n = 11) (n = 121) Viral vs. bacterial Viral vs. mixed Viral vs. no pathogen LOS inpatients, median days (IQR)12 (6–25.5)22 (13–42.5)27 (8–72)16 (8–29.25)0.0040.200.20 Complications, n (%) ICU admission29 (36.3)17 (40.5)8 (72.7)36 (29.8)0.650.050.34 Mechanical ventilation14 (17.5)15 (35.7)7 (63.6)30 (24.8)0.030.010.22 ARDS4 (5.0)5 (11.9)3 (27.3)6 (5.0)0.310.071.00 Sepsis41 (51.3)28 (66.7)7 (63.6)6 (5.0)b 0.100.44n/a Mortality (all cause)6 (7.5)4 (9.5)1 (9.1)6 (5.0)0.941.000.65 Antibiotic use (any indication) Any inpatient antibiotics, n (%)58/73 (79.5)35/38 (92.1)9/11 (81.8)90/109 (82.6)0.091.000.60 Duration of inpatient use, mean days ± SD (range)10.5 ± 13.9 (0-73)17.5 ± 15.3 (0–72)11.9 ± 10.0 (0–31)10.0 ± 10.6 (0–63)0.020.750.80 Discharged receiving oral antibiotics, n (%)17 (23.0)c 17 (44.7)d 2 (20.0)e 26 (22.8)f 0.021.000.98 ARDS acute respiratory distress syndrome, ICU intensive care unit, IQR interquartile range, LOS length of stay, n number, SD standard deviation aFor continuous variables, 2-sample independent t-test or Mann-Whitney-U-test were used. For categorical variables, Mantel-Haenszel chi square or Fisher exact test were used bSepsis requires a pathogen per definition. In these six cases sepsis was exceptionally defined according to discharge papersMissing values due to death or ongoing hospitalisation at time of analysis (number): c6; d4; e1; f7. For calculation of percentage and p-value missing values were excluded