Each year, approximately 1.2 million individuals are diagnosed with colon cancer worldwide. As the second leading cancer affecting both men and women, colorectal cancer (CRC) claims the lives of over 600,000 individuals annually. Colorectal carcinomas usually begin as benign tumors, called polyps or adenomas.
The human gastrointestinal (GI) tract is colonized by a vast and complex community of microorganisms totaling approximately 1013 bacteria composed of over 500 microbial species. Many bacteria are able to persist in the host and lead to chronic infections accompanied by inflammation. It is well accepted that microbial imbalance of the microbiota with bacterial invasion and persistence in the inner mucus layer (biofilm formation), contributes to the development or progression of inflammatory bowel disease. .Bacteria may also promote cancer through production of secondary cancer-causing toxins.
Toxins from the following bacteria have been linked to human colon cancer: Escherichia coli, Actinobacillus actinomycetemcomitans, Helicobacter, Shigella, Salmonella, Haemophilus, Campylobacter , Pasteurella multocida, Yersinia pseudotuberculosis, Burkholderia pseudomallei, Photorhabdus asymbiotica.
Source: National Institute of Allergy and Infectious Diseases (NIAID)
- Actinobacillus actinomycetemcomitans is an oral bacteria that has been associated with aggressive forms of periodontitis in adolescents, particularly in North Africa.
- Shigella causes severe inflammatory colitis, and shigellosis is one of the most easily communicable enteric diseases.
- Pasteurella multocida causes pasteurellosis, pneumonia, atrophic rhinitis, dermonecrosis, cellulitis, abscesses, meningitis, and/or hemorrhagic septicemia and high mortality, particularly in animals.
- Yersinia pseudotuberculosis can be hosted in dogs, cats, cattle, horses, rabbits, deer, turkey, ducks, and many others, as well as in soil, plants insects and amoeba in the environment. Infection generally occurs after ingestion of contaminated food or water, after which it colonizes the gastrointestinal tract and then it disseminates to the liver and spleen. Infections of Yersinia pseudotuberculosis in humans usually lead to gastroenteritis characterized by diarrhea. Generally antibiotics are not even required; however, in people with underlying chronic liver ailments or that are immunocompromised, infection has been associated with septic complications and they can develop severe and potentially fatal systemic infections.
- Burkholderia pseudomallei causes glanders. Due to the high rate of infectivity and resistance to many commonly used antibiotics, together with high mortality rate, Burkholderia pseudomallei is considered to be a potential biological warfare agent.
- Photorhabdus asymbiotica infects wounds.
- Pathogenicity of the highly leukotoxic JP2 clone of Aggregatibacter actinomycetemcomitans and its geographic dissemination and role in aggressive periodontitis. Dorte Haubek1, Anders Johansson
- Yersinia pestis and Yersinia pseudotuberculosis infection: a regulatory RNA perspective. Luary C. Martínez-Chavarría, Viveka Vadyvaloo
- Burkholderia vaccines: are we moving forward? Leang-Chung Choh et al.
- Comparative genomics of the emerging human pathogen Photorhabdus asymbiotica with the insect pathogen Photorhabdus luminescens. Paul Wilkinson et al.