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Category: Bowel Resection

Biofilm

April 26, 2020 9:44 am

Written By: Eric Baghdasaryan, Maria Vardapetyan, Osheen Abnous

Biofilm are tiny microorganism-filled communities found throughout the human gastrointestinal tract and oral cavity. These communities adhere to both biological and non-biological surfaces within the human body. They provide their inhabitants with many competitive advantages that help these bacterial communities withstand biological, chemical, and physical stresses1. Within these communities, microorganisms collaborate with one another to increase the likelihood of growth and multiplication despite the harsh conditions of the human gut. Not all bacteria within these biofilms are harmful, but those that are go on to cause infections and other severe health problems for the host. 

Biofilm formation

Studies have shown that approximately 60-80% of bacterial infections in the human body are associated with biofilm formation. Such findings have compelled researchers to investigate the complex factors responsible for biofilm formation.

Biofilm formation

Figure 1: Biofilm adhesion, formation, and maturation. whiteley.com.au/biofilms

It was shown that bacteria anchor themselves to the mocosa surface. They collectively form a protective layer made of polysaccharides, proteins, and extracellular DNA. This forms the biofilm matrix. This biofilm matrix acts as a shield against antimicrobials, toxins, and antibodies. From here, biofilm associated bacteria go on to cause chronic infections characterized by persistent inflammation and tissue damage, initiating in the gut and adjacent regions of the gastrointestinal tract. Furthermore, some biofilm associated bacteria have shown the ability to disperse from this mature biofilm to colonize new niches, underscoring the association between local infections and systemic diseases such as atherosclerosis and rheumatoid arthritis2 caused by the buildup of biofilm dispersed bacteria and subsequent inflammation in the coronary vasculature and joint capsules, respectively. In fact, BADAS syndrome (bowel associated dermatosis-arthritis syndrome) is a condition where patients present themselves with small bumps on their inner skin (mainly along the vasculature) caused by the buildup of circulating microtoxins (very small clusters of bacteria). This may lead to chronic bacteremia in the bloodstream. Also, the over circulation of host immune complexes presents many problems for the patients, such as the development of arthritis and the accompanying joint pain, caused by the build up of white blood cells in host joint capsules. Patients often link the lumps to a dermatological condition, when in reality the condition is caused by a bacterial overgrowth originating in the gut and bowel. Clinicians now believe it is very likely these bacteria are biofilm-associated and a proper early diagnosis of the biofilm origin is critical to the prevention of BADAS and similar pathologies3. 

The formation of biofilms has been studied on foreign substances such as intravenous catheters, orthopedic implants, and other biomaterials that have shown device-associated infections. However, it is commonly accepted that the majority of chronic bacterial infections involve biofilm formation on natural surfaces. The pathogenic bacterial overgrowth, forming the biofilms, have been linked to major diseases of the gastrointestinal tract including Inflammatory bowel disease and colo-rectal cancer4.

In addition to the gastrointestinal tract, biofilms can also be formed in the oral cavity. Over 700 bacterial species reside in the oral cavity. These contribute to the outgrowth of oral biofilms (otherwise known as dental plaque, see figure 2). These oral biofilms are responsible for major oral diseases such as tooth decay, gingivitis, and periodontitis. Moreover, those with periodontal infections have significantly increased risk of cardiovascular diseases, including atherosclerosis, myocardial infarction, and stroke2. The inflammation caused by oral biofilm may also be a contributing cause of conditions such as diabetes and rheumatoid arthritis1. Therefore, the control of oral biofilm growth before the development of oral infections is critical for the prevention of these system conditions.  

Dental biofilm

Figure 2: Oral Biofilm Formation.

https://phys.org/news/2018-10-scientists-infection-causing-biofilms.html

This symbiotic (mutually beneficial) relationship between gut microbiota (bacteria living in our gut) and the host begins at birth and is crucial to our overall fitness and health. However, certain external and internal factors modify the gut microbiota. This causes the formation of a pathogenic biofilm, which leads to detrimental health conditions. The same bacteria that was once helping us by maintaining a healthy gastrointestinal tract, is now triggering disease conditions4. 

Due to bacteria’s ability to translocate, migrate, and colonize new surfaces or niches, biofilm associated infections in the gut have been linked to systemic infections in other organs, including the joints, the skin, the eyes, the vasculature, the lungs, and even the central nervous system. It is assumed that the formation of a thick mucosal biofilm might be used as a diagnostic biomarker for the onset of systemic diseases. The outgrowth of a biofilm is widely viewed as the tipping point between two alternative states: a healthy and diseased gut1. 

Biofilm formation

Figure 3. Biofilm matrix – a protective layer.  Trends in Microbiology.

The biggest clinical challenge with biofilm-associated infections is their high resistance to antibiotic therapy. The effective therapeutic concentration of certain antibiotics to fight off bacteria within a biofilm (amount of the antibiotics needed in order to have positive therapeutic effects) is about 100-1000-fold higher than if the same bacteria were not associated with a biofilm2. The extracellular matrix, scaffold that keeps the bacteria anchored in place, prevents the penetration of host immune cells into the biofilm, thus contributing to the increased survival of the bacterial species living within the biofilm. Bacteria living within a biofilm also undergo an increased number of mutations, leading to the generation of more antibiotic-resistant phenotypes of bacteria. Finally, studies have shown that minimal concentrations of antibiotics may actually facilitate and stimulate biofilm formation, which can be extremely problematic in clinical treatment2. Therefore, to decrease the risk of biofilm induction, physicians should begin with very high doses of chemotherapeutics (antibiotics) from the very beginning of diagnosed infection. Looking ahead, there is clearly a need for novel biofilm-targeted therapies that are specifically made to prevent biofilm formation as well as eliminate the biofilm completely once it has already matured. Researchers have identified several drug candidates – DNase, lactoferrin, chlorhexidine, and taurolidine2 – that they believe have the potential to effectively penetrate and destroy components of the biofilm matrix. Further research is needed to determine their efficacy. 

 

References

  1. Tytgat HLP, Nobrega FL, van der Oost J, de Vos WM. Bowel Biofilms: Tipping Points between a Healthy and Compromised Gut? Trends in Microbiology. January 2019;27(1): 17-25. doi:10.1016/j.tim.2018.08.009.
  1. Marcinkiewicz J, Strus M, Pasich E. Antibiotic Resistance: a “dark side” of biofilm-associated chronic infections. Polskie Archiwum Medycyny Wewnetrznej (Polish Archive of Internal Medicine). 2013;123(6):309-312. 
  1. Dicken CH. Bowel Associated Dermatosis-Arthritis Syndrome: Bowel Bypass Syndrome Without Bowel Bypass. Mayo Clinic Proceedings. January 1984;59(1):43-46. doi:10.1016/S0025-6196(12)60341-3
  1. Buret AG, Motta JP, Allain T, Ferraz J, Wallace JL. Pathobiont release from dysbiotic gut microbiota biofilms in intestinal inflammatory diseases: a role for iron? Journal of Biomedical Science. January 2019;26(1) doi:10.1186/s12929-018-0495-4

Adhesions, Internal Hernia And Bowel Obstruction

December 15, 2018 2:35 pm

Adhesions are fibrous bands of scar tissue that form during the healing process. Following surgery, many people live normally with this scar tissue. However, they are also the cause of bowel obstruction when the adhesions form in such a way that causes a segment of the bowel to either get trapped, or form a “knot”. In both of those cases, the end result is a partial narrowing or a complete blockage of the intestines. This is called bowel obstruction.

Without treatment, the blocked parts of the intestine can die, leading to serious issues. However, with prompt medical care, intestinal obstruction often can be successfully treated.

Other causes of bowel obstruction:

  • In children, the most common cause of intestinal obstruction is telescoping of the intestine (intussusception).
  • Intussusception telescoping of the interstine
  • Hernias — portions of intestine that protrude into another part of your body
  • Inflammatory bowel diseases, such as Crohn’s disease
  • Diverticulitis — a condition in which small, bulging pouches (diverticula) in the digestive tract become inflamed or infected
  • Twisting of the colon (volvulus)
  • Impacted feces
  • Colon Cancer
Adhesion band with trapped bowel

 

Internal Hernia

In patients who haven’t Bariatric / weight loss surgery or an untouched GI track, bowel obstruction may manifest itself by symptoms of loss of appetite, constipation, nausea, vomiting, enlarged abdomen, abdominal pain, cramping, with no passage of gas or bowel movements.

However, patients who have had a weight loss surgery (Duodenal Switch, or the Gastric Bypass) because of the parallel limbs of the small bowel, the symptoms outlined above may not present. The diagnosis of a bowel obstruction, when suspected, should be identified with CT scan of the abdomen and pelvis with Oral and IV contrast. A CT scan with no oral contrast or water instead of oral contrast is inadequate and may lead to a delay in diagnosis and surgical intervention. Examples of Bowel Obstruction CT findings were discussed previously.

The treatment for an internal hernia and adhesions causing a bowel obstruction depending on the severity may range from observation to  surgical intervention in order to release the small bowel from the constraints of the adhesions.

GI Bleed following Weight Loss Surgery

September 17, 2018 10:28 am

Gastrointestinal (GI) Bleed following weight loss surgery is rare but does require knowledge of the particular bariatric surgical procedure the patients has and how to proceed with diagnostics to fully evaluate the situation. Acute or chronic gastrointestinal bleeding can cause anemia in patients. However, Anemia may also be caused by nutritional deficiencies (iron, vitamin , minerals), Kidney disease, bone marrow disease and others. The work-up for anemia following weight loss surgery follows a routine protocol. If there is an evidence of bleeding from intestine (bloody emesis, bloody bowel movement, “tar” like black bowel movements) then the diagnostic work up would include an upper and lower endoscopy.

Endoscopic Procedures:

Upper endoscopy Esophagogastroduodenoscopy (EGD): evaluates the esophagus, stomach and a limited area of the duodenum past pyloric valve.

Normal Anatomy
Normal Anatomy

Lower endoscopy Colonoscopy or coloscopy: evaluates the rectus and the entire colon.

Between these two tests, there is still a considerable amount of the small bowel that is not accessible or visualized with endoscopic procedures. For the small bowel, examination Capsule endoscopy is an option in an intact GI tract. Patients who have had Gastric bypass RNY or the Duodenal Switch, the large segments of the small bowel can not be visualized or examined with capsule endoscopy.

RNY Gastric Bypass
RNY Gastric Bypass
Duodenal Switch Two Anastomosis
Duodenal Switch Two Anastomosis
SADI-S Single Anastomosis Duodeno-ileal - Sleeve
SADI-S Single Anastomosis Duodeno-ileal - Sleeve

Patients who have had Duodenal Switch, Gastric Bypass and SADI – S would need a tagged red cell scan or CT angiography if GI bleed is suspected in areas of the small intestine that are inaccessible by endoscopic procedures.

Lymphatic Channels

May 22, 2018 8:21 am

We are all aware of the arterial and venous systems. Arteries take the oxygenated blood from the heart to the organs and the veins take the blood back to the lungs to unload the carbon dioxide and reload oxygen to be taken back to the organs. In addition to the arterial and venous vascular systems, we also have the lymphatic channels that flow into the lymphatic system.

The Lymphatic channels and system may be new to some, however, it is the third vascular network that is much less defined. The Lymphatic system collects fluids that has left the artierial/venous vascular system along their travel outlined above and take it back to the venous system. The lymphatic vessels transport this fluid to the lymph nodes throughout the body where the nodes filter the fluid of bacteria and harmful substances. Eventually, the fluid makes it way back to the venous system via the Superior Vena Cava. Additionally, Lymphatics collect the lipids within the GI tract and transport them to the venous system for metabolism. Most of the time these serosal lymphatic vessels are very small and hard to notice on the bowel.

Example of Lymphatic channels

The following image is in a patient who had small bowel obstruction. The obstruction had resulted in vascular congestion at the base of the mesentery. The congestion had effected the low pressure system of the veins and the lymphatics disproportionately more that the arterial system. The white-milky tubular structures are the lymphatic channels filled with lipids.

lymphatic channels
Visible white lymphatic channels

There are three layers to the small intestinal lymphatic system, in the villi, submucosal and serosal layers and has the unique ability to transport absorbed intra-lumenal nutrients. There is a need for further research in the areas of health, obesity and disease in regards to the lymphatic system.

Hypertrophy of Small Bowel and Weight Gain Years After Duodenal Switch

August 21, 2015 7:53 pm

Duodenal switch (DS) operation results in the highest success rate of all weight loss surgical procedures. Patients, over time, will experience some weight gain many years after DS procedure. There are a number of suspected mechanisms that may be responsible for the weight gain:

1-Ageing may slow the metabolism and the activity down.

2-Over time patients may not be as adherent to healthy dietary and lifestyle changes as they may have been immediately after surgery.

3- Hypertrophy of the alimentary and common channels over time increases in surface area f allowing greater caloric absorption leading to increased weight gain.

It has been demonstrated in bowel resection studies, as well as rat studies, that the nutrient stimulated regions of small intestine increase villus height and total weight, crypt depth and proliferation as well as wall thickness, as an adaptation to compensate for the loss of absorptive capacity in the resected bowel. This observation may be applied to DS procedure as seen in histological slides from a patient who had to have an operation done requiring bowel resection. The segment of the bowel resected included the junction of the biliopancreatic, common and alimentary limbs.

Screen Shot 2015-08-20 at 2.09.29 PM
Side by Side comparison of Biliopancreatic and the Alimentary limb