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Medical Evaluation of Functional GI Disorders
Published in Kevin W. Olden, Handbook of Functional Gastrointestinal Disorders, 2020
Michael Camilleri, Jeffrey W. Frank
There are difficulties in interpretation of breath-hydrogen tests. Early peaks may result from oral bacteria metabolizing the substrate, or from the sudden delivery of previously ingested carbohydrates to the colon. Similarly, bacterial overgrowth in the small bowel may metabolize the substrate and result in a peak in breath hydrogen. This is particularly relevant when breath testing is used in patients with significant small bowel dysmotility. Conversely, hyperventilation or exercise during the test or cigarette smoking may erroneously reduce or increase breath hydrogen, respectively (24). Previous ingestion of antibiotics or bowel cleansing will alter colonic bacteria, mitigating the accuracy of breath-hydrogen tasks. Lack of hydrogen production occurs in 6% of the population, and lower hydrogen excretion is found in those who are also methane producers (25). Finally, the accuracy of breath tests for detecting bacterial overgrowth is reduced in severe gastrointestinal motility disorders, probably due to lack of delivery of the substrate to the overgrowing bacteria (26).
Gastrointestinal tract and salivary glands
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
Symptoms of persistent or recurrent diarrhoea, abdominal pain, bloating, fever, fatigue can indicate small bowel diseases such as Crohn’s disease (particularly in young people), coeliac disease and bacterial overgrowth syndrome. Serological testing is now the first investigation recommended by NICE for suspected coeliac disease, and endoscopic biopsy can be used to confirm the diagnosis if necessary. Investigation of the small bowel for diagnosis (and assessment of complications) of Crohn’s disease has been revolutionised by MRI, offering high-quality imaging of the small bowel without a radiation risk. Classical fluoroscopic imaging of the small bowel (simple enterography or combined with fluid distension techniques) now has limited application. With an experienced operator ultrasound of the small (and large) bowel has been shown to be useful in assessment of Crohn’s disease, including detection of bowel wall thickening and strictures.
Management of Acute Intestinal Ischaemia
Published in Peter Sagar, Andrew G. Hill, Charles H. Knowles, Stefan Post, Willem A. Bemelman, Patricia L. Roberts, Susan Galandiuk, John R.T. Monson, Michael R.B. Keighley, Norman S. Williams, Keighley & Williams’ Surgery of the Anus, Rectum and Colon, 2019
Michael J. Stamos, John V. Gahagan
Drugs that treat bacterial overgrowth include antibiotics and probiotics. In patients who have a colon but lack an ileocaecal valve, colonic bacteria can reflux to the small intestine and lead to bacterial overgrowth. This overgrowth can exacerbate malabsorption and cause bloating and diarrhoea. A short course of antibiotics can decrease this bacterial load and improve symptoms. Probiotics have a theoretical benefit of replacing the overgrowth population with a less symptom-producing bacterial population, although the scientific data supporting this practice is lacking.
Is there a role for the microbiome in systemic sclerosis?
Published in Expert Review of Clinical Immunology, 2023
Bacterial overgrowth is a recognized feature of patients with long-standing SSc, historically thought to arise due to intestinal stasis. Slowing of intestinal motility facilitates the local proliferation of coliform bacteria. However, while intestinal motor complexes affect the diversity and abundance of the microbiota, new research has confirmed that this relationship is not unidirectional [12]. In other words, gut microbiota can influence motor patterns. Studies in germ-free animals demonstrate disruptions not only in motor patterns, but also in enteric neural and muscular morphology and function [12]. Colonization of germ-free rats with commensal species, such as Lactobacillus acidophilus and Bifidobacterium bifidum, reverses intestinal transit delays. Various bacterial components and products may affect motility, including short-chain fatty acids and bile salts [12].
Global transcriptional response of oral squamous cell carcinoma cell lines to health-associated oral bacteria - an in vitro study
Published in Journal of Oral Microbiology, 2022
Divyashri Baraniya, Kumaraswamy Naidu Chitrala, Nezar Noor Al-Hebshi
This was done as described previously [13]. Briefly, OSCC cells were seeded at 25,000–35,000 cells/well, depending on the cell line, in 48 well plates (TPP, Switzerland). The cells were allowed to attach for 24 h before bacteria grown to mid-log stage were added at a multiplicity of infection (MOI) of 100 – this concentration was selected based on results from our previous study in which MOI of 100 showed the highest upregulation of selected genes [13]. The co-cultures were then incubated for additional 24 hours. For each strain, a sub-minimum inhibitory concentration (sub-MIC) of streptomycin/penicillin was used to control bacterial overgrowth, as previously demonstrated [13]. All the co-cultures were performed in technical triplicates. Cells treated with culture medium devoid of bacteria were used as negative control.
Methane positive small intestinal bacterial overgrowth in inflammatory bowel disease and irritable bowel syndrome: A systematic review and meta-analysis
Published in Gut Microbes, 2021
Arjun Gandhi, Ayesha Shah, Michael P. Jones, Natasha Koloski, Nicholas J. Talley, Mark Morrison, Gerald Holtmann
Although there more than 60 peer-reviewed published studies (both case-control and prevalence studies) assessing the link between SIBO and IBS and IBD, less than half have measured both, methane and hydrogen on breath testing. It is now well acknowledged that lack of measurement of methane on routine breath testing could underestimate SIBO prevalence in various gastrointestinal conditions.14 Another important limitation is that all studies included in this systematic review and meta-analysis have only utilized breath tests (indirect testing), which are surrogate markers for diagnosing bacterial overgrowth. Methanogens are strict anaerobes57 and are exceedingly difficult to culture, requiring very specific conditions and culture media.58 Moreover, currently there is no consensus regarding the gold standard for the diagnosis of SIBO. While direct (small bowel aspirate and culture) tests are invasive, time consuming and require an endoscopy, they have been largely replaced in clinical practice by (indirect) breath tests. However, compared with culture-based methods, the GBT has a sensitivity of 62.5% and a specificity of 81.7% and the LBT has a sensitivity of 52.4% and a specificity of 85.7%.59Molecular techniques (PCR-based tests), utilizing specific primers to quantify small intestinal bacterial colonization are emerging as alternative diagnostic approaches.46