The effect of rtPCR analysis on antibiotic management is presented in Tables 8, 9 and 10. After exclusion of patients who received antibiotics for other indications virus detection was temporally associated with discontinuation of antibiotics in 2 of 20 adults (10%) and 6 of 14 children (43%). In patients with viral etiology, management was more frequently judged correct in children (18/27, 67%) than in adults (12/35, 34%; p = 0.01) after rtPCR results became available. In adults, management of viral etiology was less often judged correct compared to adults with bacterial etiology (p = 0.002). Among patients with clinically viral etiology, children were more frequently managed correctly (15/15, 100%) than adults (8/13, 62%; p = 0.03).Table 8Change of antibiotic therapy after rtPCR, adult patients with another indication for antibiotics were excluded Viral Bacterial Mixed No pathogen Clinically Clinically p-value c (n = 35) (n = 33) (n = 6) (n = 84) bacterial a (n = 84) viral b (n = 13) Viral vs. bacterial Viral vs. mixed Viral vs. no pathogen No antibiotic treatment before and after rtPCR, n (%) 10 (28.6) 7 (21.2)2 (33.3)32 (38.1)18 (21.4) 8 (61.5) 0.491.000.32Antibiotic treatment stopped after rtPCR, n (%) 2 (5.7) 2 (6.1)0 (0.0)2 (2.4)4 (4.8) 0 (0.0) 1.001.000.67Antibiotic treatment started after rtPCR, n (%)5 (14.3) 4 (12.1) 2 (33.3) 8 (9.5) 7 (8.3) 3 (23.1)1.000.540.64Antibiotic treatment before and after rtPCR, n (%)18 (51.4) 20 (60.6) 2 (33.3) 42 (50.0) 55 (65.5) 2 (15.4)0.450.710.89Correct management, n (%) 12 (34.3) 24 (72.7) 4 (66.7) 62 (73.8) 8 (61.5) 0.002 0.30n/a n number; rtPCR, real-time polymerase chain reaction aCases without detection of bacteria were evaluated as clinically bacterial if they fulfilled one of the following criteria: unilobular or multilobular pulmonary infiltrate or CRP >100 mg/l or PCT >0.25 μg/l or antibiotic therapy before rtPCR and no bacterium detection and biomarkers indeterminate (CRP >100 mg/l and PCT ≤0.25 μg/l or CRP between 51 and 100 mg/l and PCT not available) bCases with a detected viral pathogen excluding those patients with a clinically bacterial co-infection (as described above) cMantel-Haenszel chi square test or Fisher exact test were used Table 9Change of antibiotic therapy after rtPCR, pediatric patients with another indication for antibiotics were excluded Viral Bacterial Mixed No pathogen Clinically Clinically p-value c (n = 27) (n = 4) (n = 3) (n = 18) bacterial a (n = 22) viral b (n = 15) Viral vs. bacterial Viral vs. mixed Viral vs. no pathogen No antibiotic treatment before and after rtPCR, n (%) 12 (44.4) 1 (25.0)0 (0.0)6 (33.3)6 (27.3) 11 (73.3) 0.870.400.46Antibiotic treatment stopped after rtPCR, n (%) 6 (22.2) 0 (0.0)0 (0.0)1 (5.6)2 (9.1) 4 (26.7) 0.801.000.27Antibiotic treatment started after rtPCR, n (%)1 (3.7) 0 (0.0) 1 (33.3) 3 (16.7) 3 (13.6) 0 (0.0)1.000.390.34Antibiotic treatment before and after rtPCR, n (%)8 (29.6) 3 (75.0) 2 (66.7) 8 (44.4) 11 (50.0) 0 (0.0)0.230.500.32Correct management, n (%) 18 (66.7) 3 (75.0) 3 (100.0) 14 (63.6) 15 (100.0) 1.000.66n/a n number; rtPCR, real-time polymerase chain reaction aCases without detection of bacteria were evaluated as clinically bacterial if they fulfilled one of the following criteria: unilobular or multilobular pulmonary infiltrate or CRP >100 mg/l or PCT >0.25 μg/l or antibiotic therapy before rtPCR and no bacterium detection and biomarkers indeterminate (CRP >100 mg/l and PCT ≤0.25 μg/l or CRP between 51 and 100 mg/l and PCT not available) bCases with a detected viral pathogen excluding those patients with a clinically bacterial co-infection (as described above) cMantel-Haenszel chi square test or Fisher exact test were used Table 10Change of antibiotic therapy after rtPCR, all patients with another indication for antibiotics were excluded Viral Bacterial Mixed No pathogen Clinically Clinically p-value c (n = 62) (n = 37) (n = 9) (n = 102) bacterial a (n = 106) viral b (n = 28) Viral vs. bacterial Viral vs. mixed Viral vs. no pathogen No antibiotic treatment before and after rtPCR, n (%) 22 (35.5) 8 (21.6)2 (22.2)38 (37.3)24 (22.6) 19 (67.9) 0.150.710.82Antibiotic treatment stopped after rtPCR, n (%) 8 (12.9) 2 (5.4)0 (0.0)3 (2.9)6 (5.7) 4 (14.3) 0.400.640.03Antibiotic treatment started after rtPCR, n (%)6 (9.7) 4 (10.8) 3 (33.3) 11 (10.8) 10 (9.4) 3 (10.7)1.000.160.82Antibiotic treatment before and after rtPCR, n (%)26 (41.9) 23 (62.2) 4 (44.4) 50 (49.0) 66 (62.3) 2 (7.1)0.051.000.38Correct management, n (%) 30 (48.4) 27 (73.0) 7 (77.7) 76 (71.7) 23 (82.1) 0.020.19n/a n number; rtPCR, real-time polymerase chain reaction aCases without detection of bacteria were evaluated as clinically bacterial if they fulfilled one of the following criteria: unilobular or multilobular pulmonary infiltrate or CRP >100 mg/l or PCT >0.25 μg/l or antibiotic therapy before rtPCR and no bacterium detection and biomarkers indeterminate (CRP >100 mg/l and PCT ≤0.25 μg/l or CRP between 51 and 100 mg/l and PCT not available) bCases with a detected viral pathogen excluding those patients with a clinically bacterial co-infection (as described above) cMantel-Haenszel chi square test or Fisher exact test were used