什麼是肺炎

肺組織因感染、吸入異物或受照射而產生的炎症和病變，但最常見者為由細菌所引起。肺炎枝原體（Streptococcus pneumoniae）是健康人體內最常見的致病原因。支氣管和肺泡有可能發炎。咳嗽成為主要症狀，痰中可帶血斑。本病症狀嚴重，但致死率低。肺炎鏈球菌（Streptococcus pneumoniae）較常見，一般來說病情也較嚴重，但通常隻影響抵抗力較弱者，尤其是醫院內的病人。肺炎克雷伯斯菌（Klebsiella pneumoniae）引起的肺炎，幾乎只在免疫力低下的住院病患中發生，致死率很高。其他細菌性肺炎包括卡氏肺囊蟲（Pneumocystis carinii）性肺炎（少見，愛滋病患除外）和退伍軍人病。許多種類的肺炎可以抗生素治療。病毒藉削弱個體的免疫系統提供細菌性肺炎病原體滋生的環境，而非直接導致肺炎。真菌性肺炎通常發生於抵抗力低的住院病人身上，但經由受汙染的塵埃也可感染健康的人。發病快速並可能致死。胸內組織經X射線治療（參閱radiation therapy）後可導致暫時性肺炎。

pneumonia

Inflammation and solidification of lung tissue caused by infection, foreign particle inhalation, or irradiation, but usually by bacteria. Mycoplasma pneumoniae is the most common cause in healthy individuals. The bronchi and alveoli may be inflamed. Coughing becomes severe and may bring up flecks of blood. It can be serious but is rarely fatal. Streptococcus pneumoniae is more common and generally more severe but usually affects only those with low resistance, especially in hospitals. A highly lethal form caused by Klebsiella pneumoniae is almost always confined to hospitalized patients with low immunity. Other bacterial pneumonias include Pneumocystis carinii pneumonia (rare except in AIDS) and Legionnaires' disease. Most respond to antibiotic treatment. Viruses set the stage for bacterial pneumonia by weakening the individual's immune system more often than they cause pneumonia directly. Fungal pneumonia usually occurs in hospitalized persons with low resistance, but contaminated dusts can cause it in healthy individuals. It can develop rapidly and may be fatal. X-ray treatment (see radiation therapy) of structures in the chest may cause temporary lung inflammation.