Results During the same period, a total of 55 908 cardiac surgery patients were admitted, and 181 cases with bloodstream infection, with an infection rate of 0.3% (181/55 908). The results showed that CPB time (Z = 5.031, P = 0.001) and operation time (Z = 3.830, P = 0.001), usage of ECMO (χ2 = 11.569, P = 0.001), IABP (χ2 = 30.685, P = 0.001) and CRRT (χ2 = 24.761, P = 0.001), exposure to carbapenems (χ2 = 11.661, P = 0.001), quinolones (χ2 = 4.096, P = 0.043), vancomycin (χ2 = 4.096, P = 0.043) and combined antibiotics (χ2 = 13.286, P = 0.001) before infection were statistically different between infection group and non-infection group. Multivariate Logistic regression analysis showed that CPB time (OR = 5.031, 95%CI: 1.843-6.798, P < 0.001) and operation time (OR = 1.228, 95%CI: 1.056-1.427, P = 0.008), usage of ECMO (OR = 4.180, 95%CI: 1.863-9.377, P = 0.001), IABP (OR = 4.017, 95%CI: 1.572-10.267, P = 0.004), CRRT (OR = 8.586, 95%CI: 2.494-29.560, P = 0.001), exposure to carbapenems (OR = 15.742, 95%CI: 5.699-43.478, P < 0.001), quinolones (OR = 2.272, 95%CI: 1.057-4.886, P = 0.030) and vancomycin (OR = 4.297, 95%CI: 1.199-15.400, P = 0.025) and combined use of antibiotics (OR = 4.520, 95%CI: 2.154-9.484, P = 0.001) before infection were all risk factors of postoperative bloodstream infection, with statistically significant differences. The total hospital duration of patients in infection group was significantly longer than that of non-infection group, with significant difference (Z = 8.033, P = 0.001). There were 52 deaths (28.7%) in infection group and 17 deaths (9.3%) in non-infecteion group, the mortality rate of the two groups was significantly different (χ2 = 21.935, P = 0.001). Among bloodstream infection group, 37 patients (20.4%) were infected with single Gram-negative bacilli, 28 patients (15.5%) were infected with single Gram-positive cocci, 116 patients (64.1%) were infected with Gram-negative bacilli and Gram-positive cocci. Total of 234 Gram-negative bacillus strains were detected, Acinetobacter baumannii (64 strains, 27.3%) and Klebsiella pneumoniae (56 strains, 23.9%) were the most common pathogens. Total of 145 strains of Gram-positive cocci were detected, among which Staphylococcus epidermidis (69 strains, 47.6%) was the most common. The results showed that CPB time (t =-4.010, P = 0.001) and operation time (t =-8.532, P = 0.001), exposure to 3 kinds of invasive endovascular devices (χ2 = 11.723, P = 0.001) and more than 3 kinds of invasive endovascular devices (χ2 = 4.618, P = 0.032), exposure to carbapenems (χ2 = 11.661, P = 0.001), vancomycin (χ2 = 4.096, P = 0.043), linezolid (χ2 = 15.174, P = 0.001), polycolistin (χ2 = 6.353, P = 0.012) and combined antibiotics (χ2 = 13.286, P = 0.001) before infection were significantly different between multi-bacterial bloodstream infection and single negative bacteria group. Multivariate Logistic regression analysis showed that CPB time (OR = 4.851, 95%CI: 1.190-1.313, P = 0.015) and operation time (OR = 14.764, 95%CI: 1.363-17.264, P = 0.014), exposure to 3 (OR = 1.257, 95%CI: 1.046-1.510, P = 0.015) or more than 3 (OR = 1.006, 95%CI: 1.001-1.012, P = 0.032) invasive endovascular devices, usage of carbapenems (OR = 4.765, 95%CI: 1.770-12.828, P = 0.002), vancomycin (OR = 7.750, 95%CI: 1.277-4.203, P = 0.026), linezolid (OR = 3.925, 95%CI: 1.665-9.254, P = 0.002), polycolistin (OR = 1.987, 95%CI: 1.985-3.451, P = 0.020) and combined use of antibiotics (OR = 1.466, 95%CI: 1.012-1.976, P = 0.012) before infection were the risk factors of postoperative multi-bacterial bloodstream infection, and the differences were statistically significant. The length of hospital duration was significantly prolonged after multi-bacterial bloodstream infection, with significant difference (Z =-1.576, P = 0.001).