Intestinal Dysbiosis & Bacterial Overgrowth

A balanced gut microbiome supports our health and well-being in numerous ways. It plays a role in absorbing nutrients from food, keeping the immune system healthy and strong, supporting our mood and cognition, and reducing the risk of disease. A balanced gut microbiota also helps maintain a strong intestinal barrier, keeping toxins, antigens, and bacteria from entering the bloodstream.

However, an imbalance of microbes in the gut — known as dysbiosis — can impair the intestinal barrier, trigger autoimmunity, induce inflammation, and even increase the risk of chronic conditions like neurologic disorders, obesity, and metabolic diseases. This happens when there are more “bad” microbes in the GI tract than “good”, creating an imbalance of bacteria, fungi, viruses, and archaea within the gut microbiota.

What is bacterial dysbiosis?

Since human bodies are made up of more bacterial cells than human cells, an imbalance of gut bacteria can be especially problematic. Also known as dysbacteriosis, bacterial dysbiosis has been associated with everything from inflammatory bowel disease (IBD) and diabetes to cancer, allergies, and obesity. Bacterial dysbiosis can also cause general GI issues like bloating, diarrhea, abdominal pain, and constipation.

Anything that disrupts or alters the balance of the gut microbiota can trigger bacterial dysbiosis. The consequences, however, may be short-term or long-term. It really depends on the cause and severity of the bacterial imbalance.

Some potential causes of bacterial dysbiosis in the gut include:

• Antibiotic therapy.
• Certain non-antibiotic medications (e.g. proton pump inhibitors).
• Abdominal surgery.
• Diet.
• Obesity.
• Regular alcohol consumption.
• Environmental toxin exposures.
• Chronic stress.
• Poor dental health.
• Infections with pathogenic bacteria such as Clostridium difficile (C. diff) and Helicobacter pylori (H. Pylori).

Bacterial dysbiosis & SIBO

You’re probably already familiar with the most well-established type of bacterial dysbiosis affecting the GI tract: small intestinal bacterial overgrowth (SIBO). SIBO occurs when one or more species of bacteria overgrow in the small intestine, usually as a result of surgery, proton pump inhibitor usage, low stomach acid, and certain GI conditions.

On the other hand, small intestinal fungal overgrowth (SIFO) occurs when there’s an overgrowth of fungi in the small intestine. SIFO is a type of fungal dysbiosis.

What about other types of bacterial dysbiosis?

Bacterial dysbiosis can also occur outside of the GI tract, affecting the skin, mouth, vagina, and respiratory tract. Bacterial vaginosis, for example, is a type of dysbiosis that occurs as a result of bacterial imbalances in the vaginal microbiota. Gingivitis, on the other hand, occurs as a result of bacterial imbalances in the oral microbiota. Any type of dysbiosis can negatively impact our health!

Pathogenic, dysbiotic, & overgrowth bacteria in the gut

A dysbiotic gut microbiota can cause many symptoms, illnesses, and diseases in susceptible individuals, especially when the GI tract is home to high levels of opportunistic bacteria, low levels of commensal bacteria, and intestinal permeability is present. Remember, a strong intestinal lining and a balanced gut microbiota are vital for gut health and overall well-being!

Examples of the opportunistic bacteria involved in gut dysbiosis include:

• Dysbiotic and overgrowth bacteria like Bacillus spp., Enterococcus faecalis, Morganella spp., Pseudomonas spp., Staphylococcus spp., and Streptococcus spp.
• Bacterial pathogens like C. difficile, H. pylori, Salmonella, Campylobacter, and Escherichia coli (E. coli).
• Inflammatory bacteria like Citrobacter spp., Klebsiella spp., Mycobacterium avium
• subsp., Proteus spp., Enterobacter spp., Escherichia spp., Fusobacterium spp., and Prevotella spp.

Several types of dysbiotic gut bacteria are thought to be involved in SIBO, while other types of dysbiotic and overgrowth bacteria are associated with constipation, bloating, abdominal pain, diarrhea, intestinal inflammation, and autoimmune diseases. For example, high levels of Bacillus spp., Enterococcus faecalis, Morganella spp., and Streptococcus spp. have been associated with SIBO and various other GI symptoms.

Furthermore, high levels of Prevotella spp., Fusobacterium spp., and Mycobacterium avium subsp. are associated with certain autoimmune diseases like rheumatoid arthritis, systemic sclerosis, and Crohn’s disease. Other impacts of gut bacteria on human health and diseases include histamine intolerance and skin disorders like atopic dermatitis, urticaria, and eczema. The list goes on!