医院获得性肺炎(NS)一般是指病人住院48～72小时后发生的下呼吸道感染。在住院期间,临床上未呈现出症状,在出院后才表现出来的下呼吸道感染,亦应包括在内。根据美国获得性感染研究组(NNIS)的报告,在1979年,出院病人中有4.9‰发生获得性下呼吸道感染。但实际上,可能低估了20％以上,其病死率仍很高,约占25～35％。 Hospital-acquired pneumonia (NS) generally refers to a lower respiratory tract infection that occurs 48 to 72 hours after hospitalization. During hospitalization, no symptoms are present clinically, and lower respiratory tract infection that manifests only after discharge from the hospital should also be included. According to a report by the American Acquired Infection Research Unit (NNIS), in 1979, 4.9% of discharged patients developed acquired lower respiratory tract infections. However, in fact, it may have underestimated more than 20%, and its case fatality rate is still very high, accounting for 25-35%.