Oncogenous micro-organisms are confined to Mycoplasmas and Helicobacter pylori.

Among the various micro-organisms isolated from man's cancerous tissues including the blood of such patients several species were described as new to science. Their identity is being discussed and the conclusion made that none of the scientific names proposed as new for these micro-organisms can be utilized taxonomically. Aberrant red cells have been commonly confounded with some supposed blood parasites. Current research of micro-organisms suspected of playing a role in oncogenesis is confined to two categories of true or opportunistic pathogens: Mycoplasmas with respect to unspecified cancers and Helicobacter pylori in regard to stomach neoplasms.