The study is designed to clarify the clinical characteristics and reversion of children with empyema, observe the effect of streptococcus vaccine application on serotype of streptococcus, and to explore the susceptibility factors of streptococcus empyema in children in China.

Empyema is a major complication of bacterial community-acquired pneumonia in children. And studies have shown that although the incidence of community-acquired pneumonia in children has decreased with the application of pneumococcal conjugate vaccine, the incidence of empyema has increased, which raises the difficulty to disease treatment, and aggravates the financial burden on medical care.

Streptococcus is one of the most common pathogens causing children's empyema. In recent years, although more and more researches are reported on children's community- acquired pneumonia or pleural effusion, the clinical studies on streptococcus pneumoniae empyema are rarely mentioned. Therefore, a multicenter observational study is needed to better understand the clinical characteristics and reversion of children with empyema, observe the effect of streptococcus vaccine application on serotype of streptococcus, and explore the susceptibility factors of streptococcus empyema in children in China. The study mentioned above will contribute to optimize the treatment strategy of streptococcus empyema for the future, and reduce the incidence of children's empyema.

The trial will be completed in 3 years with 100 participants taken from hospitals in partnership with clinical research collaboration of National Clinical Research Center for Respiratory Diseases, China.

Inclusion Criteria:

• Age between 1 day to 18 years

• Admitted with diagnosis of pneumonia combined with pleural effusion

• The appearance of thoracic fluid or the results of fluid examination conforms to empyema with at least 1 of the following criteria:

  • Thoracentesis is pus.
  • Thoracic fluid smear observation show bacterial-positive.
  • Thoracic fluid culture test show bacterial-positive.
  • Cell counting of thoracic fluid is more than 10x109/L.

Exclusion Criteria:

• Subjects will be excluded if the thoracic fluids are caused by non-infectious factors, such as cardiovascular, connective tissue disease, tumor or trauma, etc.

Patients who are aged 1day to 18 years, and diagnosed with "pneumonia combined with empyema"