Small Intestinal Bacterial Overgrowth (SIBO) Powerpoint file pptx: https://www.mediafire.com/file/99zkmdzpoatgtaj/

1. Small Intestinal Bacterial
Overgrowth (SIBO)

2. Int.
 Intestinal microflora is a complex microbiological system composed of
parasites, viruses, yeast and, above all, bacteria (the largest population).
 It is responsible for the integrity and functioning of the gastrointestinal tract through several
mechanisms.
- Synthesis Vitamin k & some of B, role in the immune system, produce antimicrobial subs.,
& helps in digest certain foods.
 There is emerging evidence indicating that quantitative and qualitative changes in intestinal
flora contribute to the pathogenesis of intestinal and extra-intestinal diseases.

3. Int. cont.
- The number of bacteria increases from stomach (10¹ to 10³ bacteria/g) to the colon (10¹¹ to 10¹²
bacteria/g).
- The small intestine comprises mainly of Gram positive and aerobic bacteria and the large
intestine contains predominantly Gram negative and anaerobic bacteria.
- The concentration of bacteria in small bowel is generally multiple magnitudes lower than in the
large bowel due to the microenvironment and anatomical differences between the two areas.

4. Def.
-“Small intestinal bacterial overgrowth (SIBO) is a heterogeneous syndrome characterized by an
increased number and/or abnormal type of bacteria in the small bowel.”
-“Small intestinal bacterial overgrowth (SIBO) is a condition in which the small bowel is colonized
by excessive aerobic and anaerobic microbes that are normally present in the colon.”
-“Currently a bacterial concentration of >10³ c.f.u./ml is generally considered significant.”
- The small intestine typically has less than 10⁴ organisms per milliliter.

7. Several mechanisms help to maintain low
microbial numbers in a healthy small intestine
SIBO is normally prevented by the combined action of:
- Antimicrobial peptides and immunoglobulins - secreted by small intestinal epithelial cells.
-Gastric acid.
-Pancreatic enzymes.
- Peristalsis and the Migrating motor complex (MMC) - stasis promotes bacterial growth.
-Ileocecal valve - prevents reflux of colonic bacteria into the small intestine
Several intestinal and extra-intestinal disorders, leading to the disruption of one or more of
these physiologic protection systems, act as predisposing conditions to SIBO development.

8. Migrating motor complex (MMC)
 The function of MMC is to propel (sweep) any remnants of previous meal in stomach & small
intestine into colon during the inter-digestive period.
 MMC starts at stomach and migrate down the intestine and reach the IC valve.
 Activity terminates as soon as food is ingested.

9. S&S
IBS-like symptoms
 bloating, gas, abdominal pain or cramping; diarrhea, constipation, or both.
GERD symptoms
 acid reflux.
Intestinal permeability symptoms (Leaky gut)
 food sensitivities, Food intolerances such as gluten, casein, lactose, fructose and more,
headaches, skin conditions, joint pain, fatigue, anxiety, depression.
Malabsorption symptoms
 B12, iron, magnesium deficiency, weight loss, steatorrhea.

10. S&S, cont.
Bacterial gases
 The bacteria ferment food, thus causes methane, and/or hydrogen gas production.
 Bacteria produces hydrogen, which usually causes diarrhea.
 Archaea produces methane, which usually causes constipation.
 Gas causes damage to microvilli, thus disturb nutrients absorption.
 Gram-negative coliforms, such as Klebsiella species, may produce toxins that damage the mucosa,
interfering with absorptive function and causing leaky gut syndrome.

11. Clinical finding

12. Conditions that may be associated with
SIBO
IBS, GERD, acne, eczema, chronic fatigue syndrome, fibromyalgia,
gallstones, gastroparesis, hypothyroidism, celiac disease,
lactose intolerance, high cholesterol, cystic fibrosis, liver cirrhosis,
non-alcoholic fatty liver disease, obesity, diabetes mellitus,
pancreatitis, rheumatoid arthritis, positive H. pylori breath test.

14. SIBO and the Thyroid
- SIBO can lead to hypothyroidism.
- about 21% of T4 to T3 conversion occurs in the gut.
- SIBO can cause issues with the T4 to T3 conversion which can then lead to hypothyroidism.

15. Risk factors
 Anatomic
1. Blind loops:
- GI tract surgeries eg, a Billroth II procedure predisposes
to bacterial stasis and overgrowth due to abnormal motility
and ineffective clearance of retained food and secretions.
- Food is not able to follow the normal digestive route.
Instead, it bypasses a section of your intestine.
Blind loops and strictures are the most important
anatomical factor predisposing to the development of SIBO.

16. Risk factors, cont.
 Anatomic
2. Incompetent ileocecal valve
- resection of the ileocecal valve increases the risk of developing SIBO, because retrograde
movement of bacteria from the colon into the small intestine can now readily occur.
3. Small intestine diverticula
- diverticula can harbor bacteria and lead to symptoms of SIBO.
4. Post-operative adhesions

17. Risk factors, cont.
 Motility Disorders
1. Diabetic autonomic neuropathy
2. Celiac disease
3. Drugs - morphine (which inhibits MMC) develop SIBO
 Gastric
1. Hypochlorhydria or achlorhydria
2. proton-pump inhibitors
 Miscellaneous medical conditions
Crohn’s disease, Chronic pancreatitis, Cirrhosis, Immunodeficiency syndromes

18. Diagnosis
Lab investigation:
 Elevated folate with or without vitamin B12 deficiency.
Aspirate and Culture (Gold Standard).
 Cons; Invasive, contamination, and only few parts of S&L intestine can be reached.
Breath Testing
 Pros; Inexp., simple, and safe.
Stool analysis?
 Stool tests reflect the LI, not the SI.

19. Diagnosis, cont.
Breath test
 Drink substrate (lactulose).
 Lactulose transits through small intestine
- if bacteria are present, H2 (hydrogen) or CH4
(methane) gas is produced.
 H2 and CH4 absorbed through intestines into
bloodstream.
 Gases carried to lungs through bloodstream and
expired.
 Breath collected at timed points.

20. Diagnosis, cont.
 Lactulose
 Cannot be digested or absorbed by
humans, thus passes through entire
length of small intestine.
 pros: Can diagnose distal overgrowth.
 Not as sensitive as glucose.
 Glucose
 Glucose is absorbed within first few feet of
small intestine, thus can only diagnose
proximal overgrowth.
 cons: Cannot diagnose distal overgrowth.
 Accurate diagnosis of proximal
overgrowth.

22. Treatment
 Antibiotics
In the past, tetracycline, doxycycline, co-trimoxazole,
fluoroquinolones have all been used in the treatment of SIBO.
In most of the recent studies among patients with IBS, rifaximin
has been the preferred antibiotic.
 (acts against Gram positive and Gram negative aerobic and anaerobic).

23. Treatment, cont.
 Probiotics
Probiotics are live microorganisms, which, when administered in
sufficient quantities may alleviate symptoms of IBS.
Importance of probiotics:
 Improve gut barrier strength.
 Modulate gut microbiota.
 Sustain the integrity of intestinal epithelium.
 Modulate the immune system and reduce inflammation throughout the body.