Infection With Artificially Propagated Eaton Agent (Mycoplasma pneumoniae)

IN RECENT YEARS there has been considerable progress in defining the etiology of atypical pneumonia. One of the important causes of this disease is the agent described by Eaton et al in 1944.¹This agent has been associated with cold agglutinin-positive atypical pneumonia in controlled epidemiologic investigations as well as in volunteer studies.^{2, 3}In addition, Eaton agent has been shown to cause febrile respiratory disease without pneumonia.⁴ Recently it has been shown that the Eaton agent is not a virus but a pleuropneumonia-like organism which can be cultivated on a cell-free artificial medium.⁵The agent has been designatedMycoplasma pneumoniae.⁶ With the demonstration that this agent was a pleuropneumonia-like organism (Mycoplasma), it was of interest to determine if strains propagated on an agar medium could infect man. In order to test this possibility volunteers free of detectable antibody were inoculated with two strains of