This study is based on the hypothesis that the pharmacokinetics of antibiotics in children is different from adults. Cephalosporins and macrolide antibiotics are the common drugs for children with community acquired pneumonia, the investigators aim to study the population pharmacokinetics of cephalosporins and macrolide antibiotics in children receiving the drug for treatment of community acquired pneumonia, and to correlate it with treatment effectiveness and incidence of adverse effects.

Potential Impact: This novel knowledge will allow better and more rational approaches to the treatment of community acquired pneumonia. It will also set the foundation for further studies that will be able to test improved therapies that may increase treatment response in vulnerable children.

Inclusion Criteria:

• Children 1-18 years old of both sexes, with a diagnosis of community acquired pneumonia and eligible for treatment with cephalosporins and macrolide antibiotics, as per current treatment protocols.

• Community acquired pneumonia diagnostic criteria: meet any one of the 1-4 following items plus the fifth item:

  • 1. With cough, expectoration, or pre-existing respiratory disease getting worse, and with purulent sputum with or without chest pain;
  • 2. Fever;
  • 3. With pulmonary consolidation and crackles;
  • 4. White blood cells>10×10^9/L or <4×10^9/L;
  • 5. X-ray on chest shows flake, patchy infiltrate shadows or interstitial changes, with or without pleural effusion.

• Informed consent signed by the parents, and consent or assent of the patients (according to age and consenting capacity).

Exclusion Criteria:

• It is unable to provide complete medical records or the current condition can not accept the diagnosis process.
• It does not agree to participate in this study.

Children (1-18 years of age) receiving drugs per standard of care as prescribed by treating caregiver.