脆弱拟杆菌(Bacteroides fragilis, BF)是人体肠道共生菌，也是临床工作中检出率较高的厌氧菌。本研究于2020年6月—2021年12月收集从8名肿瘤患者血培养中分离的11株厌氧菌，经基质辅助激光解析电离-飞行时间质谱(matrix-assisted laser desorption ionization time of flight mass spectrometry, MALDI-TOF MS ) 技术鉴定为脆弱拟杆菌。病例分析结果显示：5名患者为结直肠癌患者；手术是脆弱拟杆菌最常见的易感因素(4/8)；临床最常使用的药物为亚胺培南西司他丁钠(4/8)；7名患者使用抗菌药物治疗后效果良好，发热缓解，感染得到控制，复查血培养结果转阴。本报道通过对肿瘤患者血流感染脆弱拟杆菌的感染因素和抗菌药物治疗进行回顾分析，以期为微生物实验室检测和临床诊治提供依据。

Bacteroides fragilis (BF) is a symbiotic bacterium in human intestinal tract, and also an anaerobic bacterium with relatively high positive rate in clinical work. 11 strains of anaerobic bacteria isolated from 8 cancer patients from June 2020 to December 2021 were identified as Bacteroides fragilis by matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS ) technique. Analysis results of medical records showed that: five patients suffered with colorectal cancer; Surgery is the most common predisposing factor of Bacteroides fragilis bloodstream infetion (4/8); Imipenem and cilastatin sodium was selected for treatment in 4 patients, and the other 4 patients took other different types of antibiotics. Seven patients who effectively treated with antibiotics got controll of fever and infection. Their reexamination results of blood culture turned to be negative. This case analysis of bloodstream infection caused by Bacteroides fragilis in cancer patients can provide evidence for microbiology detection and clinical diagnosis and treatment.