<prompt> Atypical pneumonia is caused by all exceptMycoplasmaAdeno virusChlamydiaHemophilus  <response>: Haemophilus influenza causes lobar pneumonia .it is one of the frequent cause of fatal pneumonia in the pandemic of influenza in 1918 _1919 where as atypical pneumonia is not as serious as typical pneumonia Ref:anantnarayan and panikers microbiology 10th edition 