“肺部感染”是一个不确切的诊断名词,系指肺部由于病原体引起的炎症或化脓性炎症。有些情况下,感染不容易确切定位,因而“肺部感染”可笼统指支气管—肺感染。目前,肺部感染有两个主要特点。①细菌性肺炎的致病菌以肺炎球菌最为常见,革兰氏阴性杆菌少见,病毒和霉菌更为少见。近20年来肺炎球菌感染占肺部感染的比例由85～90%下降到60%左右, “Pulmonary infection” is an imprecise diagnostic term that refers to inflammatory or suppurative inflammation of the lungs due to pathogens. In some cases, the infection is not easy to pinpoint, so “lung infection” can be broadly referred to as bronchial-lung infection. At present, there are two main characteristics of pulmonary infection. ① bacterial pneumonia pathogens to pneumococcus is the most common, Gram-negative bacilli rare, viruses and mold are more rare. In the past 20 years, the proportion of pneumococcal infections in lung infections dropped from 85% to 90% to about 60%