The mycoplasma are 'Pleuro Pneumonia Like Organisms' (or PPLO), discovered by No card and Roux (1898). Mycoplasma are the smallest free living micro-organism, ie, 0.1 to 0.5μ. They lack cell wall and it components. They occurs as granules and filaments of various sizes. They are usually resistant to antibiotics like penicillin but however they may be killed by using tetracycline and chloramphenicol.