危重症患者机械通气前后不同时段内合并严重肺感染的细菌构成与转变

目的 :探讨机械通气前后不同类型严重肺感染和抗生素应用时相应各时段的致病细菌构成与转换 ,为临床治疗提供有效依据。方法 :收集本院近年来危重症行机械通气患者共 6 2 9例 ,按肺感染的不同类型和时段 ,在使用抗生素时观察其痰中培养出致病菌的种类和构成比。结果 :院前肺感染组 (172例 )革兰阳性 (G )菌的构成比较混合肺感染组和院内肺感染组均高 (分别为 76 .0 % ,37.8% ,11.9% ) ,P均 <0 .0 1;而 G- 菌则表现为院内肺感染组及混合肺感染组较院前肺感染组高且差异显著 (分别为 88.1% ,6 2 .0 % ,2 4 .0 % ) ,P均 <0 .0 1。 3组中 G 菌以肺炎球菌、金黄色葡萄球菌和肠球菌为主 ;而 G- 菌则以绿脓杆菌、不动杆菌和克雷白杆菌为主 ,同时伴有霉菌生长。在对 112例严重肺感染患者进行继续观察时发现 ,在不同时段中可见到从 G 菌到G- 菌的动态转变。结论 :不同类型的肺感染其致病菌有显著差异 ,同种肺感染的不同治疗阶段细菌构成比也在转变。选择抗生素时既要对其致病菌有针对性 ,又要对细菌随时间而改变有预测性

Constituent ratio and change of bacterial strains in critically ill patients with severe pulmonary infection before and after mechanical ventilation

Objective:To investigate the constituent ratio and change of bacterial strains in patients with severe pulmonary infection before and after mechanical ventilation.Methods:Over the past several years,629 cases with severe pulmonary infection underwent mechanical ventilation.They were divided into 4 groups, according to pulmonary infection with different bacterial strains before and after mechanical ventilation. Results :Between pneumonia groups,the constituent ratio of G strains in bacterial infection before admission( BIBA ,76 0%) were significantly higher than that in mixed infection (MI,37 8%, P <0 01),and also than that in nosocomial infection pneumonia(NIP),including ventilator associated pneumonia (VAP,11 9%,both P <0 01).G -strains of NIP(88 1%) and MI(62 0%) were respectively common compared with that of BIBA (24 0%, P <0 01).Among G bacterial strains,prevalent bacterial strains were pneumococcosis (48 7%),staphylococcus(11 7%),enterococcus (10 0%),but G - strains were Pseudomonas aeruginosa (53 4%),Klebsiella (32 0%),acinetbacter (13 6%) respectively.The constituent ratio of G and G - strains was changed during different periods with use of antibacterial agents in pulmonary infection.Conclusions:Bacterial strains are different among various groups during pneumonia and different stages of mechanical ventilation.Therefore,the choice of antibiotics should be used according to types of the strain in pneumonia and changed with the time of mechanical ventilation.