User:Allybio0258/Carcinogenic bacteria

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Cancer bacteria are bacterial infectious organisms that are known or suspected to cause cancer. While cancer-associated bacteria have long been considered to be opportunistic (i.e., infecting healthy tissues after cancer has already established itself), there is some evidence that bacteria may be directly carcinogenic. Evidence has shown that a specific stage in cancer can be associated with bacteria that is pathogenic. The strongest evidence to date involves the bacterium H. pylori and its role in gastric cancer.

Known to cause cancer
Helicobacter pylori colonizes the human stomach and duodenum. It is described as a Class 1 carcinogen. In some cases it can cause stomach cancer and MALT lymphoma. Animal models have demonstrated Koch's third and fourth postulates for the role of Helicobacter pylori in the causation of stomach cancer. The mechanism by which H. pylori causes cancer may involve chronic inflammation, or the direct action of some of its virulence factors, for example, CagA has been implicated in carcinogenesis. Another bacteria that is in this genus is Helicobacter hepaticus, which causes hepatitis and liver cancer in mice.