Bacteroides caccae

Bacteroides caccae, a gram-negative, anaerobic bacterium, is a crucial member of the human gut microbiota, playing a significant role in metabolizing polysaccharides and oligosaccharides, thus providing nutrition and vitamins. 

It is especially important in early gut colonization, particularly in infants, influencing the colonic environment and potentially impacting health and development later in life. 

B. caccae can utilize a wide array of carbon sources, including mucins and complex sugars, creating a niche for itself and other beneficial gut bacteria. It produces anti-inflammatory molecules that help reduce inflammation, shaping the mucosal immune system and maintaining gut health. 

However, B. caccae can also become an opportunistic pathogen in compromised health conditions, capable of invading the bloodstream and causing severe infections. 

Its role in inflammatory bowel disease is complex, with some research linking it to pathogenesis while other studies suggest protective effects. Understanding B. caccae's dual roles in health and disease is crucial for developing targeted therapies and interventions.

Overview of Bacteroides spp. [1., 7., 8., 14., 20., 23., 25., 26.] 

Bacteroides spp., members of the Bacteroidetes phylum, are significant components of the human gut microbiota, crucial for maintaining gut homeostasis. 

This phylum, constituting about 30% of the human gut microbiota, includes several genera such as Bacteroides, Prevotella, and Porphyromonas. 

The proportion of Bacteroidetes varies based on population, geography, age, and diet.

Characteristics and Taxonomy

Bacteroides spp. are gram-negative, non-spore forming, anaerobic, rod-shaped bacteria. Approximately 24 species have been identified, with Bacteroides fragilis and Bacteroides thetaiotaomicron being the most studied. 

These bacteria thrive in anaerobic conditions, utilizing complex polysaccharides for energy through fermentation. 

They possess unique genetic and metabolic features that enable efficient degradation of dietary fibers and carbohydrates, producing short-chain fatty acids (SCFAs) and other metabolites that impact host physiology.

The Bacteroides genus uses a Type VI secretion system (T4SS) to maintain competitive advantage in the gut. [3.] 

The T4SS in Bacteroides helps maintain competition and balance in the human gut by releasing toxins that target other bacteria, enabling these bacteria to outcompete others and stabilize the gut ecosystem, often through the transfer of these systems via mobile genetic elements among neighboring strains. [3.] 

Role in the Human Microbiome [7., 8., 20., 26.]

Bacteroides spp. are key members of the human gut microbiome, significantly contributing to the microbial community in the colon. 

Their presence and abundance are influenced by diet, host genetics, and environmental exposures. 

Bacteroides spp. interact with other commensal bacteria and host cells, participating in complex microbial networks that regulate immune responses, nutrient metabolism, and intestinal barrier function.

Bacteroidetes, primarily found in the distal gut, possess a similar function of harvesting energy from diet through the fermentation of indigestible polysaccharides, producing short-chain fatty acids (SCFAs). [29.]

Metabolic Contributions

In adults, Bacteroides and other Bacteroidetes produce SCFAs such as acetate, propionate, and butyrate from the fermentation of undigested dietary polysaccharides. SCFAs play crucial roles in gut health, glucose homeostasis, and lipid metabolism. 

Bacteroides and Prevotella are major contributors to SCFA production, especially propionate. These bacteria adapt flexibly to the gut's nutritional environment, using a wide range of dietary polysaccharides and proteins.

Despite their diversity, Bacteroidetes share a high capacity for polysaccharide utilization, aided by numerous carbohydrate-active enzymes (CAZYmes). Their metabolic flexibility allows them to switch between different substrates based on availability and competition within the gut ecosystem. [7.] 

Diet and Bacteroidetes:

Diet significantly influences Bacteroidetes levels. 

Diets rich in animal products increase Bacteroides levels, whereas plant-based diets promote a more diverse microbial community. [7., 30.] 

Overnutrition decreases Bacteroidetes, affecting energy harvest efficiency. Conversely, undernutrition and fasting can either increase or deplete Bacteroidetes levels, depending on the conditions. [7.] 

Bacteroidetes and Metabolic Diseases:

Studies show varied associations between Bacteroidetes and type 2 diabetes. The relative abundance of Bacteroidetes can affect glucose metabolism differently in individuals, influenced by diet and other factors. 

Gnotobiotic animal studies show specific Bacteroidetes species can have different effects on host metabolism. Daily dosing with Bacteroides cultures improved glucose tolerance and insulin sensitivity in mice, suggesting microbial metabolites as potential metabolic effectors.

However, high Bacteroides have also been associated with impaired glucose tolerance. Bacteroides species' levels correlate with glucose responses post-meal, emphasizing the importance of dietary context. [7.] 

In one study, continuous blood glucose monitoring in 800 participants showed that the relative abundance of Bacteroidetes in stool was associated with a poor postprandial glucose response. [7.] 

However, within the phylum, many Bacteroides species correlated positively with a healthy postprandial glucose response when participants consumed diets optimized to their individual microbiota, dietary habits, and other factors. [7.] 

Overall, the effects of Bacteroidetes on glucose metabolism can vary significantly depending on dietary context and on the relative levels of Bacteroides subspecies. [7.] 

However, overall a healthy amount of Bacteroides seems to be beneficial for human metabolic health. [7., 11.]

Health Implications

Modulating Bacteroides metabolism through dietary interventions holds potential for restoring gut microbiota balance and promoting metabolic health. 

Imbalances in the composition of the gut microbiota, including alterations in Bacteroides spp. abundance, have been associated with numerous disease states. 

Bacteroidetes have been associated with metabolic disease, although the association between Bacteroidetes and metabolic diseases like obesity and type 2 diabetes is complex and context-dependent. [7.] 

Bacteroides has shown potential in preventing and treating non-alcoholic fatty liver disease (NAFLD) by modulating gut health.  [29.] 

By reducing liver inflammation, mitigating hepatic steatosis, and enhancing intestinal barrier function, they contribute to metabolic regulation, improve insulin resistance, and balance cytokines. 

While the mechanisms are not fully understood, Bacteroides’ ability to influence lipid metabolism and gut barrier integrity positions them as promising candidates for NAFLD therapy, although more clinical research is needed to confirm their efficacy.

What is Bacteroides caccae? [27., 28.]

Bacteroides caccae is a gram-negative, anaerobic bacterium commonly residing in the human gut, playing a crucial role in metabolizing polysaccharides and oligosaccharides to provide nutrition and vitamins. [27.] 

Health Benefits of Bacteroides caccae [10.] 

Bacteroides caccae is important in early gut colonization, particularly in infants. This bacterium is one of the first microbes to colonize the infant gut, especially in those delivered vaginally. 

Early colonization by B. caccae can influence the colonic environment and potentially impact infant health and development later in life. 

Bacteroidaceae members, including B. caccae, degrade a wide range of glycosides and may protect infants from developing allergic diseases by expressing lipopolysaccharides (LPS) and stimulating T-cell production and differentiation. [10.] 

A low relative abundance of Bacteroidaceae has been linked to the development of food allergies and atopic dermatitis in infants, highlighting the importance of early Bacteroidaceae colonization. [10.] 

B. caccae can utilize a wide array of carbon sources, including mucins and simple and complex sugars. It has the potential to utilize N-acetylneuraminic acid, cellobiose, and l-fucose, which helps create a niche for itself and other beneficial gut bacteria. 

Additionally, B. caccae produces anti-inflammatory molecules that help reduce inflammation, playing a crucial role in shaping the mucosal immune system and maintaining gut health.

One study identified a specific strain of B. caccae as a prevalent mother-child shared strain, found to be globally prevalent, indicating its widespread importance in the gut microbiota. [10.] 

It was also present in a significant portion of cesarean-born infants' samples, though less prevalent than in vaginally born infants. [10.]

In summary, Bacteroides caccae is a crucial bacterium in the human gut, especially important for early gut colonization and immune system development. It provides several health benefits, including anti-inflammatory properties and the ability to utilize diverse carbon sources. 

Its presence in infants' gut microbiota is significantly influenced by the mode of delivery, with higher colonization rates observed in vaginally delivered infants. 

Pathogenic Implications of Bacteroides caccae

While beneficial in the gut, B. caccae can become an opportunistic pathogen, particularly in individuals with compromised health. 

B. caccae in Infections

Although rare, it can invade the bloodstream, as seen in a reported case where a 42-year-old man with renal hypertension and gastrointestinal hemorrhage developed bacteremia caused by B. caccae. [27.] 

This bacterium, part of the B. fragilis group, can cause severe infections when the intestinal mucosa is damaged, highlighting the importance of accurate diagnosis using multiple blood cultures and advanced identification techniques. [27.] 

B. caccae, alongside Bacteroides thetaiotaomicron (B. theta), can degrade mucus glycans of the protective mucus layer over the epithelial lining.  

These organisms use them as an energy source, earning them the term "mucus generalists" for their metabolic flexibility in utilizing various polysaccharides, including those from dietary fibers and host mucus glycans. [18.] 

Therefore, B. caccae plays a role in either maintaining or degrading the mucus barrier based on their capacity to metabolize mucus glycans.  

Whether they protect or degrade the mucus layer depends in large part on the presence of dietary fiber in the colon, which is an alternate source of fuel for the bacteria. [18.] This shift can thin the mucus layer, heightening the risk of intestinal infections and inflammation.

B. caccae's involvement in the breakdown of mucus in the gut can compromise the intestinal barrier, leading to potential pathogen invasion, inflammatory conditions, and eventually, systemic infection. 

The increasing antibiotic resistance among anaerobic bacteria, including B. caccae, underscores the need for drug sensitivity testing to guide effective treatment. 

Preventing and managing underlying health conditions are also crucial in reducing the risk of such infections. 

B. caccae in Inflammatory Bowel Disease 

Some research has linked B. caccae with the pathogenesis of inflammatory bowel disease, although other research points to its having a protective effect. [9., 21.]

Laboratory Testing for Bacteroides caccae

Test Type, Sample Collection and Preparation

Bacteroides caccae levels are assessed in stool samples.  Stool samples may be collected from the comfort of home.  

Testing may require avoidance of certain medications and/or supplements including probiotics prior to sample collection.  It is important to consult with the ordering provider for full test preparation instructions.  

Interpretation of Test Results

Optimal Levels of Bacteroides caccae

It is important to consult with the laboratory company used for test interpretation.  Bacteroides levels are typically assessed by species, although some lesser-known species, such as B. caccae, may be reported as part of Bacteroides spp. 

One lab company provides the following reference range for Bacteroides spp. levels alongside Prevotella spp., and reports this on a scale from -3 (low prevalence of these organisms) to +3 (high prevalence of these organisms).  [16.]

Clinical Implications of High Bacteroides 

High levels of Bacteroides in the gut microbiome are generally associated with a healthy state and favorable metabolic outcomes. 

A high relative abundance of Bacteroides compared to other phyla like Firmicutes is considered essential for maintaining gut health, biodiversity, and homeostasis of metabolism, immune function, and colonization resistance.  

Bacteroidetes, the phylum of which Bacteroides are a part, are considered a "keystone taxon" in the gut microbiome, and their depletion can lead to detrimental shifts in the microbial community structure.  [12., 23.] 

Several studies have found an association between high Bacteroidetes levels and a lean phenotype or healthy weight.  A higher Bacteroidetes/Firmicutes ratio was associated with a lower body mass index (BMI).  [7., 11.] 

Conversely, a lower abundance of Bacteroidetes has been observed in obese individuals compared to lean individuals.  [7.] 

High levels of Bacteroidetes species like Bacteroides fragilis and B. thetaiotaomicron are considered beneficial as commensals, fermenting polysaccharides to produce short-chain fatty acids that serve as an energy source for the host. 

They also contribute to bile acid metabolism and provide colonization resistance against pathogens like Clostridioides difficile.  [23.]

However, elevated levels of Bacteroides in the setting of digestive symptoms or pathology warrants further assessment for bacterial strains such as B. fragilis or B. caccae, which have been associated with digestive pathology in certain settings.  

Low Bacteroides Abundance  [1., 11., 17.] 

Lower levels of Bacteroides have been associated with inflammatory bowel diseases (IBD) like ulcerative colitis, where specific Bacteroides species exhibit significantly lower abundance compared to healthy controls.

The loss of these species is suggested to result from disease exacerbation and may serve as potential biomarkers for disease activity.

Low Bacteroides levels may disrupt microbial community dynamics, favoring the overgrowth of potentially harmful bacteria and diminishing the beneficial effects of Bacteroides-mediated functions, such as the fermentation of dietary fibers and production of short-chain fatty acids (SCFAs).  [4.] 

Therefore, maintaining a high abundance of Bacteroides in the gut microbiome is generally considered a favorable state, associated with better metabolic health, a lean phenotype, and a lower risk of inflammatory conditions like IBD. 

Monitoring Bacteroides levels may have clinical significance in assessing gut health, disease risk, and potential therapeutic interventions aimed at restoring a balanced microbiome.

Treatments for B. caccae

Common Antibiotic Therapies [5.] 

Treatments for Bacteroides infections commonly center on treatment for B. fragilis infections, which is the most common organism associated with serious Bacteroides infections.  

Bacteroides spp. can cause serious infections if it breaches the mucosal barrier due to inflammation, trauma, or surgery. Proper specimen collection and prompt lab processing are crucial to avoid contamination. 

When the mucosal barrier is disrupted, it can lead to abscess formation and bacteremia, with Bacteroides fragilis producing toxins that contribute to its virulence and inhibition of clot formation, aiding its spread.

Bacteroides spp. are part of the normal colon flora but can cause significant morbidity when the mucosal lining is breached.  This is frequently seen in infections post-surgery or trauma, and in patients with malignancies. 

The bacterium is resistant to penicillin due to beta-lactamase production, with effective antibiotics including metronidazole, Piperacillin/tazobactam, and meropenem. 

However, resistance to metronidazole is emerging, with mechanisms involving nim genes, while newer antibiotics like eravacycline and tazobactam/ceftolozane show promise in treating complex infections.

Natural Ways to Optimize Microbiome Health [6.] 

A healthy diet and lifestyle are foundational for microbiome health.  

Diet and Nutrition

• Consume Diverse Foods: increase the variety of fruits, vegetables, whole grains, nuts, seeds, and legumes to promote microbial diversity.

• High-Fiber Diet: focus on fiber-rich foods to support the growth of beneficial bacteria.

• Fermented Foods: include yogurt, kefir, sauerkraut, kimchi, and other fermented foods to introduce probiotics.

• Polyphenol-Rich Foods: consume foods high in polyphenols such as berries, green tea, dark chocolate, and red wine to stimulate beneficial bacteria growth.

• Prebiotics: incorporate prebiotic-rich foods like garlic, onions, asparagus, and bananas to nourish beneficial bacteria.

Lifestyle

• Regular Exercise: engage in consistent physical activity to enhance gut microbiota diversity and composition.

• Stress Management: practice stress-reducing activities such as yoga, meditation, and mindfulness to prevent microbiota dysbiosis.

Medications and Supplements

• Probiotics: consider probiotic supplements to increase beneficial bacteria in the gut.

• Avoid Unnecessary Antibiotics: use antibiotics only when necessary to avoid disrupting the gut microbiome.

Environmental Factors

• Limit Artificial Sweeteners: avoid artificial sweeteners that can negatively affect gut microbiota.

• Healthy Sleep Patterns: maintain regular sleep patterns to support a balanced gut microbiome.

Hygiene Practices

• Avoid Over-Sanitization: limit the use of antibacterial soaps and sanitizers to maintain a healthy microbiota balance.

FAQ: Understanding Bacteroides caccae

Bacteroides caccae is a species of bacteria that plays a crucial role in the human gut microbiome. This FAQ section addresses common questions about Bacteroides caccae, its significance, and potential treatments related to its presence in the gut.

What is Bacteroides caccae?

Bacteroides caccae is a type of Gram-negative, anaerobic bacterium that belongs to the Bacteroides genus. These bacteria are commonly found in the human gastrointestinal tract, where they contribute to the digestion of complex carbohydrates and help maintain gut health.

What is the Role of Bacteroides caccae in the Gut Microbiome?

Bacteroides caccae plays a vital role in the gut microbiome by breaking down complex carbohydrates and other substrates that the human body cannot digest on its own. This process produces short-chain fatty acids, which are beneficial for gut health and overall metabolic functions.

How is Bacteroides caccae Detected?

Bacteroides caccae can be detected using various microbiological and molecular techniques, such as stool culture, 16S rRNA gene sequencing, and metagenomic analysis. These methods allow for the identification and quantification of Bacteroides caccae in the gut microbiome.

What Are the Benefits of Bacteroides caccae?

The benefits of Bacteroides caccae include aiding in the digestion of complex carbohydrates, contributing to the production of beneficial short-chain fatty acids, supporting the gut barrier function, and helping maintain a balanced gut microbiome.

Can Bacteroides caccae Be Harmful?

Under normal circumstances, Bacteroides caccae is beneficial and contributes to a healthy gut. 

However, an imbalance in the gut microbiome (dysbiosis) can sometimes lead to an overgrowth of Bacteroides species, which may be associated with gastrointestinal disorders.

What Are the Potential Treatments Related to Bacteroides caccae?

Bacteroides caccae treatment typically focuses on restoring and maintaining a healthy gut microbiome. Potential treatments include:

• Probiotics and prebiotics: to support the growth of beneficial bacteria.

• Dietary changes: including more fiber-rich foods to promote a balanced microbiome.

• Antibiotics: in cases where overgrowth or infection is suspected, though antibiotics can also disrupt the microbiome if overused.

• Fecal microbiota transplantation (FMT): in severe cases of dysbiosis, FMT may be considered to restore a healthy balance of gut bacteria.

How Can I Support the Growth of Beneficial Bacteria Like Bacteroides caccae?

Supporting the growth of beneficial bacteria like Bacteroides caccae involves:

• Eating a balanced diet rich in dietary fiber, especially from fruits, vegetables, and whole grains

• Consuming fermented foods such as yogurt, kefir, and sauerkraut

• Avoiding excessive use of antibiotics, which can disrupt the gut microbiome

• Maintaining a healthy lifestyle with regular exercise and stress management

How Does Bacteroides caccae Interact with Other Gut Bacteria?

Bacteroides caccae interacts with other gut bacteria through competitive and cooperative relationships. 

These interactions help maintain a balanced gut microbiome, where beneficial bacteria support each other's growth and function while keeping pathogenic bacteria in check.

When Should I Consult a Healthcare Provider About my Gut Microbiome?

You should consult a healthcare provider if you experience persistent digestive issues such as abdominal pain, bloating, diarrhea, or constipation. A healthcare provider can evaluate your symptoms, potentially recommend microbiome testing, and suggest appropriate treatments or dietary changes to improve gut health.

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