The importance of atypical pathogens to the guidelines of community acquired pneumonia in the world.

Atypical pathogens are very common in community-acquired pneumonia(CAP) with the morbidity of about 22%(20%～28%).Therefore,CAP guidelines around the world usually emphasize the importance of atypical pathogens.The diagnosis tests are also listed in the guidelines,but only applied among inpatients.Japanese Respiratory Society recommended the diagnosis criteria of atypical pneumonia based on the clinical characteristics for the first time in the world.All guidelines recommended that empirical antibiotic therapy should cover those atypical pathogens when Mycoplasma pneumoniae,Chlamydia pneumonia or legionella pneumophilia infection are possibly exist.Antibiotic therapy against Mycoplasma pneumoniaen and Chlamydia pneumonia should be considered among outpatients and inpatients as well as anti-legionella pneumophilia therapy in severe patients in ICU.The recommended regimen is beta-lactam antibiotics combined with macrolides or fluoroquinolones alone.