Table 1 Patient characteristics
|  | Culture negative (N = 53) | Culture positive (N = 37) | p |
|---|---|---|---|
Age, median (IQR) yrs | 59.0 (48–68) | 56.5 (38.0–66.5) | 0.275 |
Male, n (%) | 35 (66.0) | 23 (62.2) | 0.877 |
Days on MV*, median (IQR) | 8 (4.5–12.5) | 7 (5–10) | 0.697 |
Admission type, n (%) | Â | Â | 0.218 |
 Medical | 29 (54.7) | 13 (35.1) |  |
 Planned surgical | 10 (18.9) | 11 (29.7) |  |
 Emergency surgical | 13 (24.5) | 13 (35.1) |  |
 Unrecorded | 1 (1.9) | 0 |  |
Trauma, n (%) | 12 (22.6) | 18 (48.6) | 0.019 |
Neurosurgery, n (%) | 11 (20.8) | 12 (32.4) | 0.315 |
COPD, n (%) | 8 (15.1) | 5 (13.5) | 1.000 |
ARDS, n (%) | 3 (5.7) | 0 (0.0) | 0.381 |
APACHEII score, median (IQR) | 21 (15–24) | 14 (10–20) | 0.009 |
CPIS score, median (IQR) | 5 (4–6) | 7 (6–7) |  < 0.001 |
Tmax, °C, median (IQR) | 38 (37–39) | 38 (37–38) | 0.551 |
WCC, median (IQR) 109/ml | 15.5 (11.3–21.0) | 13 (11–17) | 0.074 |
PaO2/FiO2 max, median (IQR) mmHg | 240 (180–283.5) | 232.5 (168.8–283.1) | 0.85 |
Pmax, median (IQR) cmH2O | 20 (16–25) | 21 (16–24) | 0.874 |
PEEP, median (IQR) cmH2O | 8 (5–10) | 8 (5–10) | 0.983 |
Tidal volume, median (IQR) ml | 479 (429.5–580) | 538 (449–620) | 0.298 |
Genus culture results**, n (%) | Â | Â | Â |
 Enterobacter |  | 2 (5.4) |  |
 Escherichia |  | 2 (5.4) |  |
 Haemophilus |  | 4 (10.8) |  |
 Klebsiella |  | 4 (10.8) |  |
 Pseudomonas |  | 10 (27.0) |  |
 Serratia |  | 1 (2.7) |  |
 Staphylococcus |  | 13 (35.1) |  |
 Stenotrophomonas |  | 1 (2.7) |  |
ICU LOS, median (IQR) days | 18 (14.0–26.8) | 22 (16–35) | 0.154 |
Hospital LOS, median (IQR) days | 26.5 (15.5–42.8) | 34 (21.8–64.5) | 0.284 |
ICU mortality, n (%) | 12 (22.6) | 4 (10.8) | 0.244 |