Objective To evaluate the efficacy and safety of different antimicrobial regimens in patients with bloodstream infections caused by carbapenem-resistant Klebsiella pneumoniae (CRKP).Methods The clinical date of patients with CRKP bloodstream infections were retrospectively analyzed at the First Affiliated Hospital of Zhejiang University Medical College between January 2017 and January 2018.All subjects were separated into three groups based on antibiotics regimens over 72 hours,including meropenem 2.0 g every 8 hours,tigecycline 200 mg as initial dose and 100 mg every 12 hours,and polymyxin B 1.25 mg/kg every 12 hours as salvage treatment of tigecycline.Results A total of 86 patients were finally recruited,including 14,52 and 20 patients in groups of meropenem,tigecycline and polymyxin B salvage,respectively.All of the strains were resistant to meropenem and susceptible to tigecycline and polymyxin B initially,while 2 of them became resistant to tigecycline during treatment.The 28-day mortality was significantly higher in meropenem group (13/14) than that in tigecycline group and polymyxin B salvage group (61.5％,32/52) and (12/20),respectively (P＜0.01),while as no significant difference was seen in the last two groups (x2=0.014,P＞0.05).The incidences of hepatic impairment [3.8％(2/52) vs.1/20] and renal dysfunction (0 vs.1/20) between tigecycline group and polymyxin B salvage group were both comparable (P＞0.05).Conclusion The meropenem-based therapy is not recommended for CRKP-related bloodstream infections.Tigecycline-based therapy is still disappointing despite salvage use of polymyxin B after 72 hours.Hepatic and nephretic toxicities caused by additional polymyxin B are acceptable.