<P> Distinction between atypical and typical pneumonia is, however, medically insufficient . For the treatment of pneumonia, it is important to know the exact causal organism . </P> <P> "Primary atypical pneumonia" is called primary because it develops independently of other diseases . </P> <P> "Atypical pneumonia" is atypical in that it is caused by atypical organisms (other than Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis). These atypical organisms include special bacteria, viruses, fungi, and protozoa . In addition, this form of pneumonia is atypical in presentation with only moderate amounts of sputum, no consolidation, only small increases in white cell counts, and no alveolar exudate . At the time that atypical pneumonia was first described, organisms like Mycoplasma, Chlamydophila, and Legionella were not yet recognized as bacteria and instead considered viruses . Hence "atypical pneumonia" was also called "non-bacterial". In literature the term atypical pneumonia (contrasted with bacterial pneumonia) is still in use, though incorrect . Meanwhile, many such organisms are identified as bacteria, albeit unusual types (Mycoplasma is a type of bacteria without a cell wall and Chlamydias are intracellular parasites). As the conditions caused by these agents have different courses and respond to different treatments, the identification of the specific causative pathogen is important . </P> <P> Usually the atypical causes also involve atypical symptoms: </P>

Which of the following organisms causes primary atypical pneumonia quizlet