The document discusses the gut microbiome, noting that the human intestine contains over 100 trillion microorganisms consisting of about 500 bacterial species that play an important role in health by aiding nutrient absorption, training the immune system, and preventing pathogenic bacteria overgrowth, while alterations in the gut flora balance due to factors like antibiotics, illness, or diet can impact conditions such as inflammatory bowel disease, obesity, and cancer.

2. WORLD DIGESTIVE HEALTH
DAY
 29th May.
 Bangladesh Gastroenterology Society
creating awareness nation-wide.

3. Slogan
Gut microbes-
Importance in health and disease

4. Dr. Jimma Hossain
MBBS, MD (Gastro)
Assistant Professor
Department of Gastroenterology
Rangpur Medical College & Hospital

5. Gut flora
 Gut flora consists of a complex of
microorganism species.
 Human intestine carries about 100 trillion
microorganisms.
 Ten times greater than total cell in body.

6. Gut flora
 About 500 different species live in gut.
 Bacteria makeup the majority.
 Over 99% of bacteria are anaerobes.
 Fungi, protozoa and archaea also part of gut
flora,but little is known about their activities.

7. Gut flora
 Most bacteria belong to genera
Bacteroids,Clostridium,Fusobacterium,Eubacterium,Ruminococcu
s,Peptococcus,Peptostreptococcus and Bifidobacterium.
 Bacteroids alone constitute 30%.
 Fungi include Candida, Saccharomyces,
Aspergillus and Penicillium.
 Archea another large class of flora important
for metabolism of bacterial products of
fermentation.

8. Gut flora and diet
 Association between concentration of
microbial community and dietary components.
 Prevotella with carbohydrate based diet.
 Bacteroids with animal protein diet.
 Gut flora can be changed by following a long
term diet.

9. Acquisition of gut flora
 At birth digestive tract is sterile.
 Colonised by microbes within first few days.
 All infants initially colonized by E.coli and
Streptococci and subsequently anaerobes
predominate.
 Breast fed babies predominated by
Bifidobacteria.
 With introducton of other foods,a diverse
microbial population develops.

10. Gut flora and health
 Research suggests relationship between gut
flora and humans not merely commensal ,but
rather mutualistic.
 Though people can survive without gut
flora,microorganisms perform a host of useful
functions.

11. Gut Flora
A healthy digestive system should contain at least 80-
85% friendly bacteria to prevent diseases caused by
organisms like E. coli & salmonella.
Stomach
10¹-10³ cfu/ml
Jejunum/Ileum
104-107 cfu/ml
Colon
10¹¹-10¹² cfu/ml
Duodenum
10¹-10³ cfu/ml

12. Useful Functions
 Recycle energy by fermenting unused energy
substrate.
 Early development & training of the immune
system.
 Prevention of the growth of harmful pathogenic
bacteria.
 Regulation of the development of gut.
 Production of vitamins such as biotin, folate and
vitamin K.

13. Useful Functions
 Antidiabetic,anticarcinogenic,hypocholesterol
emic role.
 However,in certain conditions,some species
capable of causing disease by producing
infection,increasing cancer risk for the host.

14. Fermentation
 Saccharolytic - more favorable.
 Proteolytic- less favorable.

15. Saccharolytic fermentation
 Carbohydrates fermented into short chain
fatty acids(SCFAs).
 Acetic acid,propionic acid and butyric acid.
 These are used by enterocytes and other
cells and helps mineral absorption.
 Butyric acid provides energy to gut cells and
prevents cancer.

16. Butyrate
Potential Mechanisms of Anti-neoplastic Action

17. Proteolytic Fermentation
 Breaks down proteins like enzymes,dead host
and bacterial cells,collagen,elastin.
 Can produce toxins and carcinogens in
addition to SCFAs.

18. Trophic effects
 SCFAs increase growth of intestinal epithelial
cells and control proliferation and
differentiation.
 Growth of the lymphoid tissue near the gut.
 Prevents cells from injury.
 Prevents cancer.

19. Suppression of pathogenic microbial growth
 Prevents harmful bacteria through competitive
exclusion.
 By competing for nutrition and attachment sites to
epithelium.
 Produce bacteriocins that kills harmful microbes.
 By producing acids during fermentation lowers
colonic PH and thus prevents proliferation of harmful
species and facilitating helpful species.
 By influencing mucosal barrier.
 By influencing immune function.

21. Immunity
 Gut flora have regulatory effects on mucosal
immune response.
 Key in promoting early development of gut’s
mucosal immune system.
 Stimulate lymphoid tissue associated with the
gut to produce antibodies to pathogens.

22. Immunity
Modulation of immune response by flora
Stimulation of mucosal immunity
* Better oral vaccine responses
* Control infections
Suppression of mucosal immunity
* Reduce allergy
* Reduce inflammation

23. Prevention of allergy
 Can influence tolerance of gut immune
system to antigens
 Helpful gut flora stimulate immune system
and train it to respond properly to antigens.
 Lack of these bacteria in early life leads to an
inadequately trained immune system that
over reacts to antigens.

24. Prevention of allergy
 Composition of gut flora varies in patients
with/without allergies.
 In allergy: Bacteroides, Bifidobacteria
S.aureus, C.difficile

25. Prevention of inflammatory bowel disease
 SCFAs prevent IBD.
 Some form of bacteria can prevent
inflammation.
 Linked to good hygiene in youth.
 Inversely linked with poor sanitation during
first year of life.
 Antibiotics that kill native bacteria.
 High concentration probiotics decrease
inflammation.

26. Alteration in flora balance
 Inflammation
 Antibiotic use
 AAD

Irritating bowel directly

Changing levels of gut flora, alteration in flora balance.

Allowing pathogenic bacteria to grow

Decreased ability to ferment CHO and bile acids

Over growth of C.difficile
 Gut flora composition also changes in severe illness,
ischaemia, immune compromise.

27. Alteration in flora balance
 Pharmabiotics
 Generic term to encompass any form of
therapeutic exploitation of commensal flora
 Use of live probiotic bacteria,pre-
biotics,synbiotics(genetically modified
commensal).
 Pre-biotics : dietary components that foster
the growth of micro organisms in the gut
 Pregnancy.
 Wt loss.

28. Role in disease
 Have pathogenic properties in addition to
their health-inducing ones.
 They can produce toxins and carcinogens.

29. Role in disease
 Implicated in conditions as MOF,sepsis,colon
cancer and IBD.
 A major factor in health is the balance of
bacterial numbers ; if too high or low,will harm
the host.

30. Role in disease
 Some genera-Bacteroids and Clostridium
associated with in increase in tumor growth
rate.
 Lactobacillus and Bifidobacteria are known to
prevent tumor formation.

31. Role in disease
 Bacterial translocation in certain conditions
causes sepsis.
 Implicated in colitis, obesity.

32. Conclusion
 The gastrointestinal tract is now considered one of
the most complex microbial ecosystem on earth.
 Till to date, little is known about this ecosystem.
 Researches are going on to explore undiscovered
aspects of gut flora in health & disease.