肺炎支原体（Mycoplasma pneumoniae、霉浆菌性肺炎）是一种可导致肺炎的支原体细菌，也有机会导致冷凝集素症(cold agglutinin disease)。这种由肺炎支原体引起的肺炎，又称作霉浆菌性肺炎。

大多数患者只有轻微上呼吸道感染，有咳嗽、发烧、喉咙痛、头痛及疲倦等征状，但严重者则可能患上肺炎，属于非典型肺炎的一种。

由于霉浆菌性肺炎不能用一般的肺炎药来医治，所以即使儿童感染了霉浆菌性肺炎，也只能用原来用于医治成人肺炎的强效药物来医治。

Mycoplasma pneumoniae is a very small bacterium in the class Mollicutes. It is a human pathogen that causes the disease mycoplasma pneumonia, a form of atypical bacterial pneumonia related to cold agglutinin disease. M. pneumoniae is characterized by the absence of a peptidoglycan cell wall and resulting resistance to many antibacterial agents. The persistence of M. pneumoniae infections even after treatment is associated with its ability to mimic host cell surface composition.