Mortality due to K. pneumoniae bacteremia is on rise, particularly in regions with high rates of carbapenem and colistin resistance. We aimed to define risk factors for colistin resistance and its impact on mortality. Patients diagnosed with “carbapenem-resistant K. pneumoniae (CRKp)” bacteremia between 2014 and 2018 were divided into two groups as “colistin susceptible (ColS)” and “colistin resistant (ColR)” based on broth microdilution method. Retrospective case-control study was conducted to compare characteristics and outcomes. Multiple logistic regression model was used to define independent risk factors for acquired colistin resistance and Cox proportional hazard model for 28-day mortality. A total of 82 patients (39 ColS and 43 ColR) were included. Mean age was 61.5 years, and 50 (61%) were male. Colistin resistance was significantly increased with duration of hospital stay (p = 0.007) and prior colistin use (p = 0.007). Overall, the 28-day mortality rate was 66%. Age (p = 0.014) and colistin resistance significantly increased 28-day (p = 0.009) mortality. Microbiological response to treatment within 7 days favors survival. PFGE analysis revealed an outbreak with K. pneumoniae ST78 and ST45 clones. Patients treated with combined antimicrobials had significantly lower 28-day mortality (p = 0.045) in comparison to monotherapy. However, types of combinations did not show significant superiority on each other. Colistin resistance increases 28-day mortality in CRKp bacteremia. Although combined regimens are more effective than monotherapy, existing antibacterial combinations have no apparent superiority to each other. New treatment options are pivotal.

肺炎克雷伯菌菌血症导致的死亡率正在上升，尤其是在碳青霉烯类和粘菌素耐药率高的地区。我们旨在确定粘菌素耐药性的危险因素及其对死亡率的影响。确诊为“耐碳青霉烯类肺炎克雷伯菌”的患者(CRKp)” 2014-2018年间菌血症根据肉汤微量稀释法分为“粘菌素敏感（ColS）”和“粘菌素抗性（ColR）”两组。进行回顾性病例对照研究以比较特征和结果。多元逻辑回归模型用于定义获得性粘菌素耐药的独立危险因素和 28 天死亡率的 Cox 比例风险模型。总共包括 82 名患者（39 名 ColS 和 43 名 ColR）。平均年龄为 61.5 岁，其中 50 人 (61%) 为男性。粘菌素抗性与住院（的持续时间增加显著p = 0.007），并在使用粘菌素（p = 0.007）。总体而言，28 天死亡率为 66%。年龄 ( p= 0.014) 和粘菌素抗性显着增加 28 天 ( p = 0.009) 死亡率。7 天内对治疗的微生物反应有利于存活。PFGE 分析揭示了肺炎克雷伯菌ST78 和 ST45 克隆的爆发。与单药治疗相比，联合抗菌药物治疗的患者 28 天死亡率显着降低 ( p = 0.045)。然而，组合类型之间并没有表现出明显的优势。粘菌素耐药性增加 CRKp 菌血症的 28 天死亡率。虽然联合方案比单一疗法更有效，但现有的抗菌组合彼此之间没有明显的优势。新的治疗选择至关重要。