It is well known that both bacterial and viral infections are capable of causing pneumonia, and mycoplasma pneumonia is a pneumonia caused by Mycoplasma pneumoniae. In fact, Mycoplasma pneumoniae is the more common pathogen causing pneumonia, and about 10-20% of all pneumonia is caused by mycoplasma infections. Mycoplasma pneumonia has not been known for a long time; more than 60 years ago, foreign scholars described a pneumonia with an unknown pathogen that was different from the typical pneumonia caused by Streptococcus pneumoniae and did not respond to penicillin treatment, so it was called “atypical pneumonia”. As research progressed, it was realized that the pathogen causing this pneumonia was Mycoplasma pneumoniae. Mycoplasma pneumoniae differs from common bacteria and viruses in that it is the smallest microorganism that can live independently, with a size of 200 μm. It is transmitted through the air by oral and nasal secretions and causes respiratory infections, mainly in children and adolescents, but also in adults, in the fall and winter. Mycoplasma pneumoniae infection of the respiratory tract can lead to pneumonia, i.e. mycoplasma pneumonia, which can also manifest as pharyngitis and tracheobronchitis. Mycoplasma pneumoniae infects humans after an incubation period of 2 to 3 weeks, followed by clinical manifestations, and about 1/3 of cases can also be asymptomatic. It starts slowly, with initial onset of sore throat, headache, fever, malaise, muscle aches, loss of appetite, nausea, vomiting, etc. The fever is usually moderate, but may be high or no fever. 2-3 days later, there are obvious respiratory symptoms, highlighted by a paroxysmal irritating cough, mainly at night, with a small amount of mucus or mucopurulent sputum, sometimes with blood in the sputum. There may also be dyspnea and chest pain. The fever may last for 2 to 3 weeks, and the cough may remain after the body temperature has normalized. Although the patient feels that the symptoms are heavy, there are usually no obvious abnormal signs on physical examination of the chest. About half of them can hear dry or wet rales. The nose is mildly stuffy and runny, and the pharynx is moderately congested. The ear drum is often congested, and about 15% have tympanitis. The cervical lymph nodes may be enlarged. A small amount of pleural effusion occurs in about 10% to 15% of cases. In addition to respiratory manifestations, mycoplasma pneumonia may be associated with multisystem and multiorgan damage. Skin damage may manifest as maculopapular rash, erythema nodosum, and blistering rash. Occasionally, nonspecific myalgia and wandering arthralgia are seen. Vomiting, diarrhea and hepatic impairment are seen in the gastrointestinal system. Hematologic damage is more common with hemolytic anemia. Central nervous system damage can be seen as polyneuritis, meningoencephalitis and cerebellar damage. Cardiovascular system lesions occasionally include myocarditis and pericarditis. Chest X-rays are highly variable, and lesions can be mild or extensive. Sometimes there is only an increased hilar shadow or cloudy pulmonary infiltrate, and rarely there is a large lobar solid shadow and visible pulmonary atelectasis. Sometimes diffuse reticular, nodular infiltrative shadows or interstitial pneumonia are seen bilaterally. Mild signs and significant chest radiograph shadows are one of the features of the disease. Routine blood tests show varying levels of white blood cells, mostly normal, sometimes high. Blood sedimentation shows moderate increase. The clinical manifestations and chest X-ray examination of Mycoplasma pneumonia are not characteristic and the diagnosis cannot be made based on clinical manifestations and chest X-ray examination alone. To make a definitive diagnosis, pathogen testing is required. A positive mycoplasma culture using the patient’s sputum or pharyngeal swab can confirm the diagnosis. Because of the high requirements for mycoplasma culture and the time required for 2-3 weeks, few units in China perform this test. Currently, the diagnosis of mycoplasma pneumonia relies mainly on serologic testing. Serum-specific antibody assay has diagnostic value and is often used clinically by complement binding test, indirect hemagglutination test, indirect immunofluorescence method and enzyme-linked immunosorbent assay. In addition, enzyme-linked adsorbent assay can be used to detect antigens. In recent years, domestic and foreign applications of molecular biology methods, such as DNA probes and PCR detection of Mycoplasma pneumoniae DNA, diagnosis has the advantages of rapid and high specificity, but not widely used in clinical practice. Mycoplasma pneumoniae is mainly treated with antibacterial drugs, and the course of treatment is mostly about 2 weeks. Mycoplasma pneumoniae has no cell wall, so the commonly used penicillin and cephalosporin antibacterial drugs are ineffective, and the effective drugs are mainly macrolide antibacterial drugs (such as erythromycin and azithromycin) and fluoroquinolones (such as levofloxacin and moxifloxacin). Macrolide antibacterial drugs, especially azithromycin, are considered to be the drug of choice for Mycoplasma pneumoniae pneumonia because of their better therapeutic effect than erythromycin and less vascular irritation and fewer gastrointestinal reactions such as diarrhea, abdominal pain, loose stools, nausea, and vomiting. Mycoplasma infections can cause small epidemics, so attention should be paid to respiratory isolation and keeping indoor air fresh. As cough is the most prominent clinical manifestation of mycoplasma pneumonia, frequent and violent cough may affect the patient’s sleep and rest, and small doses of cough suppressants, such as codeine, can be given appropriately. Expectorant treatment can promote sputum thinning and easy discharge, reducing the chance of combined bacterial infections. Oxygen should be administered in a timely manner to those with severe hypoxic manifestations. Except for those with severe wheezing, bronchodilators such as aminophylline can be used for oral administration. In the acute stage of rapid development of severe mycoplasma pneumonia or pulmonary lesions with extended pulmonary atelectasis, interstitial fibrosis, bronchiectasis or extra-pulmonary complications, adrenal corticosteroids can be applied appropriately. A diet of easily digestible, nutritious food and adequate fluids is appropriate.