Irritable bowels or IBS, with or without small intestinal bacterial overgrowth - SIBO - may include a breakdown of the intestinal barrier followed by systemic inflammation or antibody cross-reactivity leading to autoimmunity in other parts of the body.


Cyrex Array 22 is helpful to:

  • Identify the overgrowth of large intestinal bacteria in the small intestine and the release of bacterial cytotoxins
  • Evaluate a breach of intestinal barrier by bacterial cytotoxins and their entry into circulation
  • Assist in determining treatment protocols of irritable bowels/SIBO to reduce risk of igniting the autoimmune process, or reverse autoimmune processes that are underway


Cyrex Array 22 is recommended for those who have one or more of the following:

  • Have or suspect they have IBS
  • Have or suspect they have SIBO
  • Exhibit symptoms of malabsorption, including weight loss, anaemia or fatty stools
  • Have conditions such as fatigue, reflux, skin disorders, obesity or food intolerances
  • Have autoimmune reactivity / autoimmune disease
  • Inconclusive results from the SIBO Breath Test


Irritable bowel syndrome (IBS) and small intestinal bacterial overgrowth (SIBO) are functional gastrointestinal disorders suffered by an estimated 10% or more of the population. To the frustration of both patients and clinicians, there has to date been a significant lack of sensitive and specific evaluation strategies, and as such as many as 75% of sufferers fail to seek medical care.


Owing to the range of clinical symptoms expressed in patients with irritable bowels and/or SIBO, and the overlap in symptom presentations with other gastrointestinal disorders (Coeliac disease, lactose intolerance, Crohn’s disease and inflammatory bowel disease) identifying causes and accurate diagnosis can prove challenging.


A large portion of IBS occurs exclusively after infection with bacteria such as E. coli, Samonella, Shigella and Campylobacter jejuni. All these organisms produce in common cytolethal distending toxins, which have a major role in the disruption of both tight junction and cytoskeletal proteins such as vinculin, talin and α-actinin, thus weakening the epithelial cells which line the intestinal wall. Dysregulated immunity, low-grade inflammation and altered gastrointestinal (GI) permeability, the presence of mood disorders, fatigue, fibromyalgia and migraine found in up to 70% of patients add complexity to the accurate diagnoses of these disorders. Currently, IBS diagnosis is made by exclusion of disorders that mimic IBS and by focusing on IBS common symptoms.


Furthermore, it is common for patients with SIBO to have symptoms that overlap with IBS. SIBO is defined as the presence of excessive gut bacteria in the small intestine that originates from the large intestine. Similar to IBS there is currently no definite test for the diagnosis of SIBO. The breath tests (lactulose/glucose), whilst providing much helpful information can be both problematic to carry out and render many false positives and some false negative results. Consequently Cyrex Array 22 has been developed as a blood test for the determination of IBS/SIBO.


The goals of lab testing in IBS and SIBO patients is to determine the cause and to establish the diagnosis as early as possible in order to initiate successful treatment regimens. Cyrex Array 22 measures IgA, IgG and IgM antibodies against bacterial cytotoxins and cytoskeletal proteins in human blood. This is based on the scientific fact that bacteria from the colon move up to the upper gut, and their concentrations become elevated. By producing cytotoxins, these bacteria affect the delicate environment of the small intestine, and then gain entry into the cell, where, by binding to the cellular DNA, they induce apoptosis (cell death). They then find their way to the submucosa, regional lymph nodes, and into the circulation. Immune response against the bacterial cytotoxins may result in the production of IgA, IgM and IgG antibodies against them.

Due to the antigenic similarity between E. coli, Salmonella, Shigella toxins, Campylobacter jejuni and human cytoskeletal proteins such as vinculin and talin, these antibodies cross-react with the cytoskeletal proteins, causing depolymerization of and release of these proteins from the epithelial cells, with subsequent antibody production against the cytoskeletal proteins vinculin, talin, and actinin. These IgA, IgM and IgG antibodies against bacterial cytotoxins and cytoskeletal proteins are detected in the blood with high accuracy and reproducibility. Thus, bacterial over-growth can be an instigator of extra-intestinal autoimmunity (autoimmune reactivity outside of the gastrointestinal tract).


A disrupted gut microbiome can occur due to a variety of reasons. Once the gram-negative bacteria begin to thrive, they may use their toxins to infiltrate and obliterate gut epithelial cells.


This results in a broken intestinal barrier allowing for the translocation of bacterial toxins such as lipopolysaccharides (Array 2) from the gut into the blood to circulate throughout the body. Systemic bacterial products contribute to systemic inflammation.


Cytoskeletal proteins from intestinal epithelial cells are also found in other body barriers. This production of antibodies against gut cytoskeletal proteins due to broken intestinal barrier may contribute to autoimmunity against the cytoskeletal proteins in various parts of the body.


Summarily, bacteria can have far-reaching effects. When the intestinal microbiome is altered, cytotoxins from gram negative bacteria are released. These cytotoxins assist the bacteria in the invasion of epithelial cells where they attack the cell’s DNA. This causes a breakdown in the intestinal barrier, releasing bacterial cytotoxins and other immunogens into the bloodstream. The systemic inflammation due to these immunogens may play a role in autoimmune reactivity in the body.


Cyrex Array 22 – Irritable Bowel / SIBO Screen assesses IgG, IgA and IgM antibodies to Bacterial Cytotoxins and to Cytoskeletal Proteins. Cytotoxins are lethal xenobiotics released by commensal coliform bacteria. Bacterial cytotoxins can destroy epithelial cells of the intestinal barrier. Therefore, Cyrex also assesses antibodies to cytoskeletal proteins. Once this epithelial cell damage occurs, bacterial cytotoxins can freely enter circulation. Like systemic lipopolysaccharides (Array 2 – Intestinal Antigenic Permeability Screen), when bacterial cytotoxins enter the blood stream, they produce chronic inflammation and can permeate the blood brain barrier (Array 20 – Blood-Brain Barrier Permeability Screen). With Array 22, one can identify a trigger of irritable bowels and the specific intestinal barrier damage they cause and thus help to direct treatment protocols.

For further guidance or questions re Cyrex Testing? Please refer to the Cyrex Testing Process or follow the Order and Pay link below.

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Photography by Shirley Bloomfield-Davies