Extended-spectrum β-lactamase (ESBL)-positive bloodstream infection (BSI) is on the rise worldwide. The purpose of this study is to evaluate the impact of inappropriate initial antibiotic therapy (IIAT) on in-hospital mortality of patients in the emergency department (ED) with Escherichia coli and Klebsiella pneumoniae BSIs. This retrospective single-center cohort study included all adult patients with E. coli and K. pneumoniae BSIs between January 2007 and December 2013, who had undergone a blood culture test and initiation of antibiotics within 6 h of ED registration time. Multiple logistic regression was used to adjust for bacterial species, IIAT, time to antibiotics, age, sex, quick Sepsis Related Organ Failure Assessment (qSOFA) score ⩾ 2, and comorbidities. A total of 3533 patients were enrolled (2967 alive and 566 deceased, in-hospital mortality rate 16%). The patients with K. pneumoniae ESBL-positive BSI had the highest mortality rate. Non-survivors had qSOFA scores ⩾ 2 (33.6% vs 9.5%, P < 0.001), more IIAT (15.0% vs 10.7%, P = 0.004), but shorter mean time to antibiotics (1.70 vs 1.84 h, P < 0.001). A qSOFA score ⩾ 2 is the most significant predictor for in-hospital mortality; however, IIAT and time to antibiotics were not significant predictors in multiple logistic regression analysis. In subgroup analysis divided by qSOFA scores, IIAT was still not a significant predictor. Severity of the disease (qSOFA score ⩾ 2) is the key factor influencing in-hospital mortality of patients with E. coli and K. pneumoniae BSIs. The time to antibiotics and IIAT were not significant predictors because they in turn were affected by disease severity.

全球范围内，广谱β-内酰胺酶（ESBL）阳性血流感染（BSI）呈上升趋势。这项研究的目的是评估不适当的初始抗生素治疗（IIAT）对急诊科（ED）大肠杆菌和肺炎克雷伯氏菌BSI患者的院内死亡率的影响。这项回顾性单中心队列研究包括了所有患有大肠杆菌和肺炎克雷伯菌的成年患者在2007年1月至2013年12月之间的BSI，他们在ED注册后6小时内接受了血培养测试并开始使用抗生素。多元logistic回归用于调整细菌种类，IIAT，使用抗生素的时间，年龄，性别，败血症相关器官衰竭快速评估（qSOFA）得分≥2和合并症。共有3533例患者入组（2967例存活和566例死亡，医院内死亡率为16％）。肺炎克雷伯菌ESBL阳性BSI患者的死亡率最高。非幸存者的qSOFA得分⩾2（33.6％vs 9.5％，P  <0.001），IIAT更高（15.0％vs 10.7％，P  = 0.004），但平均抗生素使用时间更短（1.70 vs 1.84 h，P <0.001）。qSOFA得分≥2是院内死亡率的最重要预测因子；然而，在多对数回归分析中，IIAT和使用抗生素的时间并不是显着的预测指标。在亚组分析中除以qSOFA分数，IIAT仍不是重要的预测指标。疾病的严重程度（qSOFA得分⩾2）是影响大肠杆菌和肺炎克雷伯氏菌BSI患者住院死亡率的关键因素。服用抗生素和IIAT的时间并不是重要的预测指标，因为它们反过来又受到疾病严重程度的影响。