HWN Suggests

Mysterious Virus Hiding Inside Common Gut Bacterium Linked to Colorectal Cancer

Studying the microbiome of colorectal cancer patients has become a growing field, aimed at understanding microbes’ role in the disease and improving early diagnosis. One bacterium, Bacteroides fragilis, has repeatedly been linked to colorectal cancer. However, it is also common in healthy people. “It has been a paradox that we repeatedly find the same bacterium in connection with colorectal cancer, while at the same time it is a completely normal part of the gut in healthy people,” said Damgaard. When analyzing bacterial samples from patients who later developed colorectal cancer, the researchers discovered a virus living inside B. fragilis. These bacteriophages are viruses that infect bacteria,…

read full article

Featured

 A tale of two habitats: Bacteroides fragilis, a lethal pathogen and resident in the human gastrointestinal microbiome

B. fragilis is not a primary invasive enteric pathogen; however, if colonic contents contaminate the extra-intestinal host environment, it successfully adapts to this new habitat and causes infection; classically peritoneal infection arising from rupture of an inflamed appendix or GI surgery, which if untreated, can progress to bacteraemia and death

Articles of Interest

Bacteroides fragilis uses toxins for gut success

Bacteroides fragilis employs two different mechanisms, secreted microbe- and host-targeting toxins, that facilitate successful colonization of the mammalian gastrointestinal tract.

Bacteroides: the Good, the Bad, and the Nitty-Gritty

Bacteroides species are significant clinical pathogens and are found in most anaerobic infections, with an associated mortality of more than 19%. The bacteria maintain a complex and generally beneficial relationship with the host when retained in the gut, but when they escape this environment they can cause significant pathology, including bacteremia and abscess formation in multiple body sites.

Resources

StatPearls

The human colon possesses the largest population of bacteria in the body, and the majority of these organisms are anaerobes; of these, about 25 percent are species of Bacteroides. Bacteroides fragilis is part of the normal microbiota of the human colon. Disruption of the mucosal surface either by inflammation, trauma, or surgery and spread of Bacteroides fragilis to the bloodstream or surrounding tissues results in clinically significant infection.