Characteristics of Mycoplasma: (i) Cell wall is absent and plasma membrane forms the outer boundary of the cell. (ii) Due to the absence of cell wall these organisms can change their shape and are pleomorphic and are inherently resistant to lactam antibiotics (e.g., penicillin). (iii) Lack of nucleus and other membranebound organelles. Genetic material is a single DNA duplex and is naked. Ribosomes are 70 S type. (iv) Shows Heterotrophic nutrition. (Saprophytes and parasitic). M. pneumoniae causes lung infections such as walking pneumonia. (v) They are found in the pleural cavities of cattle suffering from pleuropneumonia. These organisms are often called PPLO (pleuropneumonia-like organisms). Related Theory In the treatment of mycoplasmal pneumonia, antimicrobials against M pneumoniae are bacteriostatic, not bactericidal. Tetracycline and erythromycin compounds are very effective as they are protein synthesis inhibitors.