Abstract

In the last few years much has been learnt about the ‘pleuropneumonia-like organisms’ which are now known as the genus Mycoplasma.^{1 2} ‘Eaton agent’ has now been renamed Mycoplasma pneumoniae. It is an organism about the size of the larger viruses, but differs from them in that it is free-living. It has no rigid cell wall and is not affected by penicillins, which kill bacteria by interfering with the synthesis of the cell wall.