Mycoplasma Pneumoniae - History

History

M. pneumoniae was historically known as "Eaton's agent".

First M. pneumoniae was considered as a virus rather than a bacterium, when Eaton and colleagues cultured the causative agent of human primary atypical pneumonia (PAP) or "walking pneumonia". This agent could be grown in chicken embryos and passed through a filter that excluded normal bacteria. However, it could not be observed by high magnification light microscopy, and it caused a pneumonia that could not be treated with the antimicrobials sulphonamides and penicillin. Eaton suggested the possibility that the disease was caused by a mycoplasma, but the agent did not grow on the standard PPLO media of the time. These observations led to the conclusion that the causative agent of PAP is a virus. Researchers at that time showed that the cultured agent could induce disease in experimentally infected cotton rats and hamsters. In spite of controversy whether the researchers had truly isolated the causative agent of PAP (based largely on the unusual immunological response of patients with PAP), in retrospect their evidence along with that of colleagues and competitors appears to have been quite conclusive. There were reports linking Eaton's Agent to the PPLOs or mycoplasmas, well known then as parasites of cattle and rodents, due to sensitivity to antimicrobial