医院获得性肺炎(Nosocomial pneumonia,NP)是指病人住院48～72小时后才发生的下呼吸道感染,包括肺炎、化脓性支气管炎、肺脓肿等。在美国,据估计每年有225～300万NP,占全部医院获得性感染(Nosocomial Infections,NI)的第三位(15％),仅次于泌尿道感染(40％)与外科伤口感染(22％)。Gross等从长期住院死亡的200病例中发现,1/3为NI,下呼吸道感染占40％,肺炎又占 Nosocomial pneumonia (NP) is a type of lower respiratory tract infection that occurs 48 to 72 hours after hospitalization, including pneumonia, suppurative bronchitis, and lung abscess. In the United States, it is estimated that 2.2 to 3 million NPs annually, representing the third (15%) of all hospital-acquired Nosocomial Infections (NI), second only to urinary tract infections (40%) and surgical wound infections %). Gross and other long-term hospitalized in 200 cases were found, 1/3 for NI, lower respiratory tract infection accounted for 40% of pneumonia and accounted