Gram -ve obligate , intracellular pathogens exists in two forms Elementary body - metabolically inactive- Reticulate body - larger replicative form ,formed once EB recognised it replicate, then reorganised to EB that spread further. there are three types

C.Pneumoniae : spread by droplet and cause pulmonary pneumonia , pharyngitis and extra pulmonary myocarditis and meningocephalitis

C.Pasittaci : airborne inhalation of infected dropping of birds .. cause acute flu like symp, Atypical pneumonia .. complications are rare but severe , respiratory failure ,hepatitis , endocarditis , encephalitis life threatening in pregnancy

diagnosis : PCR , NAAT serology for IgG and cell culture , treatment : tetracycline and macrolide