Small Intestinal Bacterial Overgrowth(SIBO)

Post Gastrectomy

Ahmed Abdelwanis

Research Fellow, Upper GI, St Jame’s University Hospital

Overview

• What is SIBO?• Factors protecting against SIBO• Associated Clinical Disorders• Pathophysiology & Clinical Picture• Testing for SIBO• SIBO & Gastrectomy• Treatment

What is SIBO?

The Gut Microflora in Healthy individuals

• There is small numbers of bacteria in the stomach and

small intestine.

• These bacteria are usually gram positive aerobes,

anaerobes are rare.

• Colonic anaerobes are not normally found in the

proximal small intestine

Small Intestinal Bacterial Overgrowth(SIBO)

Definition

The presence > 105 (colony forming units) CFU/ml

of small intestinal aspirate in the proximal small

intestine

Factors Which Protect Against SIBO

GASTRIC ACID

INTESTINAL MOTILITY

IC Valve

Pancreatic & Biliary Secretions

Mucosal Immune System

Disorders Commonly Associated with SIBO

Gastric acid secretion

Pancreatic / Biliary enzymes

Motility Disorder ImmuneDeficiency

Structural Defect

Potent acid suppressive drugs

Atrophic gastritis

Vagotomy

Chronic pancreatitis

Pancreatic insufficiency

Cirrhosis

Aging

Celiac sprue

Cirrhosis

Crohn’s disease

DM

Pseudo-obstruction

Renal failure

Radiation enteritis

Scleroderma

Immuno- suppressive Rx

CVID

IgA deficiency

Fistula

IC valve resection

Bariatric surgery

Gastrectomy

Small bowel div.

Surgical blind loop

Pathophysiology & Clinical Picture

SIBOSIBO

Glycosidase &Protease

• (-) disaccharidase enzyme• Bile Inactivation• inflammatory cytokines• Intestinal Permeability

(leaky gut)

CHO malabsorption

CHO malabsorption

Steatorrhea/ Vit Def

Steatorrhea/ Vit Def

Systemic Sx’sSystemic Sx’s

Hydrogen/Methane/CO2/H2S

Hydrogen/Methane/CO2/H2S

Fermintation Fermintation

Bloating\FlatulenceDiarrhea\Constipation

Abdominal Pain

Damage The Brush Border

Clinical Picture• Abdominal pain, including cramping

• Constipation (methane)

• Diarrhea (hydrogen)

• Excessive flatulence

• Malabsorption problems, i.e. fat soluble vitamins, vitamin B12, iron

• Systemic complaints such as fatigue, body pain, joint pain, headaches

Testing for SIBO

Culture of Jejunal Aspirate

Gold Standard This however, is not an ideal method of diagnosis:

•Costly and invasive method•High rate of false negative results•Technical problem•Risk of oral contamination

Hydrogen Breath Test (HBT)

Bacterial Concentration,Organisms/mL

<102

>105

Methods of Detection

Direct Aspiration and Culture

Glucose Breath Test

Lactulose Breath Test

Glucose

Lactulose

HBT

HBT Interpretation

• The exhaled gas is measured in parts per million (ppm)

• The fasting baseline of expired hydrogen should be <10ppm (ideally <5ppm)

• majority of studies suggest that a hydrogen peak exceeding 10-20 ppm above baseline is indicative of a positive glucose test

HBT Drawbacks

• Glucose is absorbed completely in proximal small intestine

• Time consuming procedure (especially in slow transit)

• Methane/H2S producing Bacteria

• +ve HBT may not always mean that a patient's symptoms are caused by SIBO

SIBO & Gastrectomy

Stomach FunctionsReservoir

Mixes &GrindsControls gastric emptying

Destroys ingested bacteria

Secretes digestive juices

Nutritional consequences after gastrectomy

• Dumping Syndrome (Early & Late)

• Vitamin B12 deficiency

• Iron Deficiency Anaemia

• Calcium deficiency

Significance of SIBO in post-gastrectomy patients

• SIBO is expected in post-gastrectomy patients however

its role has not been clarified

• Studies are trying to identify prevalence, symptoms and

Malnutrition and their relation to SIBO

Paik et al 2011• Paik et al examined a total of 76 patients for

bacterial overgrowth postgastrectomy• 59 SIBO +ve & 17 SIBO –ve• SIBO appears to be a cause of postprandial

intestinal symptoms. Moreover, SIBO positive postgastrectomy patients might have a risk for late hypoglycaemia

• There were no differences regarding age, gender, the time interval from operation, type of operation, and the presence or type of dumping syndrome

It is clear that future studies are needed to

fully understand the role of SIBO in

postgastrectomy patients by demonstrating

the response to antibiotic treatment of SIBO

Treatment• Correct predisposing condition if possible

• Correct Nutritional Deficiencies

• Diet Management

• Antibiotics • Probiotics

Diet

Antibiotics

There exists no consensus on the most efficacious dose or duration of

treatment

Antibiotics

• Empiric

because the contaminating bacterial populations are quite numerous, choice of antibiotic remains primarily empiric

• Meta-analysis by Shah et al 2013

Antibiotics appear to be more effective than placebo for breath test normalisation in patients with symptoms attributable to SIBO, and breath test normalisation may correlate with clinical response

Antibiotics

1) Amoxicillin-clavulinic acid (30 mg/kg/day)

2) Metronidazole (20 mg/kg/day) + cephalosporin

(30mg/kg/day)

3) Norfloxacin (800 mg/day)

4) Doxycyclin (200 mg/day)

5) Rifaximin (1650 mg/per day)

• The antibiotic Rifaximin is poorly absorbed

• In a randomized controlled trial, 142 patients with SIBO were randomized to seven days of rifaximin (1200 mg/day) or metronidazole (750 mg/day), glucose breath test normalization rates at one month were significantly higher in patients treated with rifaximin compared with metronidazole

Rifaximin

Probiotics• One pilot study assessed the effect of Lactobacillus casei

on SIBO patients, Following the 6-week intervention, 64% of patients no longer had a positive breath test, but there was no significant improvement in abdominal symptoms

• In another pilot study, patients were randomised to receive either a probiotic or metronidazole. A statistically significant difference in symptomatic response favoured the use of the probiotic over the antibiotic

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