<prompt> Primary atypical pneumonia is caused byLegionellaStreptococcusMycoplasmaListeria  <response>: Ans. c Mycoplasma. Textbook of Microbiology by Anantanarayan 6th365MYCOPLASMA Bacteria devoid of cell walls Highly pleomorphic Eaton agent Pleuropneumonia like organisms. Smallest free living micro-organisms. Do not produce spores, flagella or fibria. Gliding motility present. Fried egg appearance of colonies positive. Colonies best studied by staining with Dienes method. Cold agglutination test streptococcus MG. Pathogenicity- M. pneumonia -Primary atypical pneumonia.- Ureaplasma urealyticum and M.hominis -genital infection Treatment--tetracycline erythromycin. 