Bacteroides fragilis

Optimal Result: 1.6 - 250 x10^5 CFU/g.

Bacteroides fragilis plays an important physiological role in the adult colon. Bacteroides is a Gram-negative, non-spore forming, obligate anaerobic bacteria normally found in the human intestines, mouth, upper respiratory tract, and genital tract. Bacteroides expresses polysaccharide A, which can induce regulatory T cell growth and cytokine expression that are protective against colitis.

There are 160 major bacteria among the 1,000 to 1,150 species of bacteria which colonize the human intestinal tract. Two dominant microflora in the human distal gut, Bacteroides and Firmicutes phyla, account for 90% of the bacterial flora. 

Inflammatory bowel diseases:

Many studies have related Bacteroides to the development of IBD. Inflammatory bowel disease (IBD) which includes Crohn’s disease (CD), ulcerative colitis (UC), and indeterminate colitis (IC) is a chronic relapsing inflammatory disorder of the gastrointestinal tract of unclear etiology. One hypothesis is that the inflammation results from altered microbiota in a genetically susceptible host. Intestinal flora in healthy individuals can demonstrate significant variety. As individuals age, their intestinal microbial flora tend to become more similar. There is a healthy balance of microflora in the gastrointestinal tract in normal individuals. This balance is disrupted in disease.

Possible treatment options:

Several lines of evidence support the notion that gut dysbiosis contributes to the pathogenesis of IBD. Beneficial bacteria are less abundant while pathogenic bacteria are increased in IBD patients. This imbalance of the gut microbiota is not merely a secondary consequence of disease. Rather, it is thought that a dysbiotic microbiota has inflammatory potential and/or interfere with protective/regulatory function of the immune system. Hence, novel therapeutic strategies that selectively target dysbiosis have attracted considerable interest and offer hope for more effective IBD treatment options. 

For instance, fecal microbiota transplantation (FMT), which aims to restore normal gut microbial composition and function appears to be an effective treatment for IBD. It has been shown that FMT can be effective for the treatment of CDI in IBD patients, resulting in the normalization of altered microbial composition and metabolic function, and elimination of C. difficile. Indeed, microbial diversity and richness in IBD patients treated with FMT increase and become similar to those of healthy donors. Additionally, FMT restores secondary bile acid metabolism in the intestine and ameliorates gut damage. Thus, FMT seems to be a promising therapeutic approach that restores/enhances microbiota-mediated resistance to pathogens. 

Likewise, dietary intervention is another approach used to restore normal microbial composition and function, as it has been reported that diet is a powerful driver of microbial structure in the gut. Elemental diet has been used in the treatment of IBD, in particular to manage the symptoms of CD. Cohort studies have shown that elemental diet has an impact on the composition of the gut microbiota, and induces mucosal healing and clinical remission of CD. Mounting evidence suggests that a diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) can effectively reduce GI symptoms in patients with irritable bowel syndrome by altering microbial composition and luminal metabolism. In this context, pilot studies have demonstrated that a low-FODMAPs diet can significantly ameliorate gut dysfunction in some IBD patients.


What does it mean if your Bacteroides fragilis result is too low?

Low Bacteroides fragilis levels have been associated with inflammatory bowel disease and Crohn's.

Bacteroides fragilis is an anaerobic, Gram-negative bacterium. It is part of the normal microbiota of the human colon and is generally commensal. Bacteroides fragilis plays an intricate role in the human colon and usually has a beneficial relationship with the host.

Treatment may involve the use of probiotics and dietary modification.


Bacteroides fragilis is a species of bacterium found in the human colon and is a member of the Bacteroidetes phylum. While B. fragilis is often present in small amounts in most individuals, its levels can vary significantly between individuals due to diet, genetics, health status, and other factors.

Low levels of Bacteroides fragilis in the colon can have several implications:

→ Gut Microbiome Diversity: Low levels might indicate reduced microbial diversity in the gut, which is generally associated with a range of health issues.

→ Diet: Diet plays a significant role in shaping the gut microbiome. Diets low in fiber and high in fats and simple sugars can reduce the abundance of Bacteroidetes, including B. fragilis.

→ Immune Modulation: B. fragilis produces a specific polysaccharide (polysaccharide A or PSA) that has been shown to have anti-inflammatory effects and plays a role in modulating the immune system. Low levels of B. fragilis might be associated with altered immune regulation.

→ Gut Health: While B. fragilis can have beneficial effects due to its anti-inflammatory properties, it is also an opportunistic pathogen. In certain conditions, especially when the gut barrier is compromised, it can cause infections or contribute to inflammatory processes. However, low levels would reduce this risk.

→ Association with Diseases: Some studies have shown that imbalances in Bacteroides species, including B. fragilis, might be linked with certain diseases, including inflammatory bowel disease (IBD) like Crohn's disease and ulcerative colitis. However, it's essential to note that the direction of causality is not clear — whether the microbial imbalance causes the disease or is a result of it.

→ Antibiotic Use: Antibiotics can significantly alter the gut microbiome composition, often reducing the abundance of many commensal bacteria, including B. fragilis. If an individual has recently taken antibiotics, it could explain the reduced levels.

→ Inter-individual Variation: It's important to recognize that there's significant variation in the microbiome composition between individuals. What might be a "normal" or "optimal" level for one person might not be the same for another.

It's essential to interpret the results within the broader context of the individual's overall health, diet, medication use, and other factors. Consulting with a healthcare professional who has expertise in gut health and microbiome analysis is crucial for a comprehensive understanding and any potential interventions.

What does it mean if your Bacteroides fragilis result is too high?

Elevated levels of Bacteroides fragilis can have significant implications for gut health. Bacteroides fragilis is a type of bacteria normally present in the human gut, playing a role in digestion and maintaining the intestinal barrier. However, when its levels become disproportionately high, it can be indicative of a disrupted gut microbiome, a condition often referred to as dysbiosis. This imbalance can lead to various gastrointestinal issues, such as abdominal discomfort, bloating, and changes in bowel habits. In some cases, it might also be associated with more serious conditions like inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, or infections, especially if the patient is immunocompromised.

Treatment for elevated Bacteroides fragilis often involves addressing the underlying cause of the dysbiosis. This could include dietary modifications, like increasing fiber intake or reducing foods that disrupt gut flora balance. Probiotics and prebiotics can also be beneficial in restoring a healthy gut microbiome. In cases of infection or severe gut inflammation, antibiotics or anti-inflammatory medications may be prescribed. However, antibiotic use should be approached cautiously, as it can sometimes exacerbate dysbiosis by further disrupting the microbial balance.

It's important to note that treatment should be tailored to the individual's specific condition and symptoms, and managed by a healthcare professional. They might also recommend lifestyle changes, stress management techniques, or other interventions based on the patient's overall health and specific circumstances. Regular monitoring and follow-up tests may be necessary to assess the effectiveness of the treatment and make adjustments as needed.

10 000+ happy customers
100% satisfaction
★ ★ ★ ★ ★ customer support

Trust us to examine your lab results, guiding you towards improved health.

Use promo code to save 10% off any plan.

We implement proven measures to keep your data safe.

At HealthMatters, we're committed to maintaining the security and confidentiality of your personal information. We've put industry-leading security standards in place to help protect against the loss, misuse, or alteration of the information under our control. We use procedural, physical, and electronic security methods designed to prevent unauthorized people from getting access to this information. Our internal code of conduct adds additional privacy protection. All data is backed up multiple times a day and encrypted using SSL certificates. See our Privacy Policy for more details.