IBS

Question 1

Irritable Bowel Syndrome
Diagnostic Criteria*

Answer 1

◦ Recurrent abdominal pain, on average, at least 1
day per week in the last 3 months, associated with
two or more of the following:
 1. Related to defecation
 2. Associated with a change in frequency of stool
 3. Associated with a change in form (appearance) of stool
 * Criterion fulfilled for the last 3 months with symptom
onset at least 6 months prior to diagnosis

Question 2

Irritable Bowel Syndrome
Subjects with IBS can be subdivided by their
symptoms into subtypes

Answer 2

◦ Constipation-predominant (C-IBS)
◦ Diarrhoea-predominant (D-IBS)
◦ Mixed IBS (M-IBS or DA-IBS)
◦ Unsubtyped IBS

Question 3

Irritable Bowel Syndrome
Aetiological Factors

Answer 3

Enhanced visceral perception –
 patients with IBS have been found to have increased visceral
sensation and visceral hyperalgaesia compared to healthy
controls (Delvaux, 2002)(Camilleri et al, 2002)

◦ Low-grade inflammation – (Camilleri et al, 2002)(Bercik et al, 2005)
 IBS patients show no identifiable inflammation on routine
colonic biopsies
 some do show increased expression of inflammatory
markers
 i.e., increased enterochromaffin and mast cell numbers, increased
intraepithelial T lymphocytes and increased mucosal interleukin-1 β
messenger RNA
 suggesting low-grade inflammation is present
 this mild mucosal inflammation is theorised to cause local
disruptions to neuromuscular function

◦ Altered GIT motility – (Coulis, 2001)(Serra et al, 2001)
 in C-IBS - significant delays in overall colonic transit
and decreased numbers of fast and propagated
colonic contractions compared to healthy controls
 in D-IBS – more rapid ileocolonic transit and colonic
transit
 impaired transit of intestinal gas

Altered GIT microflora (dysbiosis) –
 colonic fermentation studies have found patients with
IBS to produce significantly more colonic hydrogen
than healthy controls, as well as having altered faecal
short-chain fatty acid profiles (King et al, 1998)(Treem et al, 1996)
 lower faecal concentrations of bifidobacteria and
lactobacilli (Si et al, 2005)(Malinen et al, 2005)(Balsari et al, 1982)
 higher concentrations of Enterobacteriaceae

Question 4

Irritable Bowel Syndrome
Risk Factors

Answer 4

◦ Familial disposition (Morris-Yates etal, 1995)(Locke et al, 1996)
 may contribute to the development of IBS in some patients
 this predisposition may not be disease specific but more
related to alterations in the responsiveness of the central
nervous system to stimuli

◦ Acute gastrointestinal infections (McKendrick and Read, 1994)(Gwee et al,
1999)(Mayer, 1999)(Rodriguez and Ruigomez, 1999)(Thabane et al, 2007)(Dai and Jiang, 2012)
 long-lasting alterations in mucosal function and structure
may be responsible for post-infective IBS
 increased intestinal permeability, increased expression of
inflammatory markers (such as interleukin-1β), and neuromuscular
dysfunction

◦ Antibiotic use (Mendall and Kumar, 1998)(Maxwell et al, 2002)(Villarreal et al, 2012)
 probably mediated via antibiotic-induced alterations in the
GIT microflora and/or enhanced visceral sensitivity

◦ Stressful and traumatic life events
 frequently reported to precede the initial onset of IBS
symptoms and symptom flare-ups in patients already
suffering from IBS (Bennett et al, 1998)(Whitehead et al, 1998)
 IBS has consistently been found to have a high degree of
psychiatric co-morbidities (Masand et al, 1995)(Hochstrasser and Angst, 1996)
 such as dysthymia, depression, panic disorder, and generalised
anxiety disorder

Question 5

Irritable Bowel Syndrome
Consequences

Answer 5

◦ substantial impact on QOL
 Impacts physical functioning, mood, sexual functioning,
social functioning and even sleep
◦ economic
 absent 3-5% of work week
 report impaired productivity ~30% of the week
◦ substantial healthcare burden
 3.6 million visits annually in US due to IBS
 >$20 billion annually in direct and indirect expenditures

Question 6

IBS –Treatment Aims

Answer 6

Optimise GIT microflora
‘Normalise’ bowel habit
Manage GIT symptoms
Support the nervous system
Decrease gut inflammation and diminish visceral
hypersensitivity
Improve liver function
Assess and manage food allergens and intolerances

Question 7

How Optimise GIT Microflora

Answer 7

Prebiotics
Probiotics
Role for Antimicrobials?

Question 8

Optimise GIT Microflora -
Prebiotics

Answer 8

Galactooligosaccharides (GOS)
◦ R, SB, PC, CO (Silk et al, 2009)
 3.5 g/day GOS or 7.0 g/day or placebo for 4 weeks to subjects
with IBS
 Results:
 3.5 g/day
 improvement in stool consistency, flatulence scores, bloating scores,
and overall IBS symptom scores compared to placebo (all P<0.05)
 7.0 g/day
 improvements in overall IBS symptom scores and a reduction in
anxiety levels compared to placebo (both P<0.05)
 increase in bloating scores relative to baseline (P<0.05

NB - FOS txt no better than placebo at end of trial

Question 9

Optimise GIT Microflora - Probiotics

Answer 9

Lactobacillus plantarum 299v (Ducrotte et al, 2012)
◦ R, DB, PC; n=214
 all IBS sub-types included
◦ L.. plantarum 299v (1 x 1010 CFU/day) for 4 weeks
◦ Results:
 the frequency and severity of abdominal pain, bloating, and
feeling of incomplete evacuation scores were significantly
reduced in the 299v group compared to controls (all
P<0.05)
 stool frequency was significantly reduced in the 299v
group (P<0.05)
 78% of subjects in the 299v group scored the symptomatic
effect as excellent or good vs 8% of controls (P<0.01)

Question 10

Manage GIT Symptoms
Three gastrointestinal symptoms have the
greatest negative impact upon quality of
life:

Answer 10

◦ straining at stool
◦ abdominal pain
◦ abdominal bloating