机械通气时发生院内感染的革兰氏阴性杆菌肺炎死亡率高达70%～80%,但因缺乏敏感且特异的方法而使诊断困难.经纤支镜保护性标本刷(PSB)培养虽好,但需24～72h。用支气管肺泡灌洗液离心,革兰氏、姬姆萨染色,检查多形核细胞内细菌(ICB)是一种快速方法。当含菌细胞>7%时,即预示PSB 培养必为阳性结果。但尚不知抗生素的使用对结果有何影响.共36例患者49例次机械通气相关性肺炎,分为 The death rate of Gram-negative bacilli pneumonia during nosocomial ventilation was as high as 70% -80%, but it was difficult to diagnose due to the lack of sensitive and specific methods.Although the culture of bronchoscopic brush (PSB) But need 24 ~ 72h. Centrifugation with bronchoalveolar lavage fluid, Gram, Giemsa staining, check polymorphonuclear bacteria (ICB) is a rapid method. When bacterial cells> 7%, indicating that the PSB culture will be positive results. However, it is unknown how the use of antibiotics affected the outcome.A total of 36 patients with 49 cases of mechanical ventilation-related pneumonia were divided into