This document discusses the human microbiome, which refers to the microorganisms that inhabit different areas of the human body. It notes that the microbiome develops immediately after birth and includes bacteria, yeasts and protozoa. The microbiome plays an important role in health, such as immune system development, but can also contribute to diseases. The document then describes the types of microbes typically found in different body sites like the gut, skin, respiratory and genitourinary tracts.

1. Welcome

2. Dr. Hamima Hasnat
M.B.B.S , M. Phil (Microbiology)
Assistant Professor
Eastern medical college, Cumilla
BACTERIABacteria

3. Human
Microbiome: The
undiscovered
country

5. Human microbiome
• The human microbiome is the distinct microbial communities
that inhabit different host environment on the body’s skin and
mucosal surface. The term microbiome encompasses all of the
genetic material associated with these organisms.

6. • In short, human microbiome means the entire inhabitant
microorganisms, their genomes, their capabilities and the
surrounding environment.

7. • These microbes are often referred to as commensals, which are
organisms that derive benefit from another host but do not
damage that host.

8. • Human microbiomes are the permanent residents of the body
in all humans.
• Some people can be transiently colonized, either for short or
long periods, with certain organisms, but those are not
considered members of the human microbiome.

9. • Carrier state:
The term carrier implies that an individual harbors a potential
pathogen and therefore can be a source of infection of others.
It is most frequently used in reference to a person with an
- asymptomatic infection or
- someone who has recovered from a disease but continues to
carry the organism and may shed it for a long period.

10. • Colonization:
Colonization is the presence of bacteria on a body surface (like
on the skin, mouth, intestines or airway) without causing
disease in the person.
• Infection:
Growth and multiplication of a microbe in or on the body of
the host with or without the production of disease.

11. • When we get colonized with human microbiome?
Immediately after birth.

12. Human microbiomes are either,
• Bacteria
• Yeasts,
• Protozoa.

13. We all have microbes.

14. What part of the human body is sterile?
•The internal organs usually are sterile such as the central
nervous system, blood, lower bronchi and alveoli, liver, spleen,
kidneys, and bladder.
• But the occasional transient microbial intrution occurs after
modest trauma (after flossing of teeth) or abration on the skin.

15. • Variation in the abundance and complexity of the microbiome
constituents is observed within any individual over time and
certainly between individuals.
• However within the first few years of life our microbial
communities mature and become relatively stable unless
perturbed, such as by antibiotic treatment.

16. Contribution of microbiome to health and
disease

17. 1. A healthy microbiome helps to develop immune system. Like
the gut microbiota influences the maturation and function of
the immune response.

19. 2. The nonpathogenic resident bacteria occupy attachment sites
on the skin and mucosa that can interfere with colonization by
pathogenic bacteria (Colonization resistance).
• For example, antibiotics can reduce the normal colonic flora
that allows Clostridium difficile, which is resistant to the
antibiotics, to overgrow and cause pseudomembranous colitis.

20. 3. Play an important role in several body functions and diseases,
such as weight control (obesity), inflammatory bowel disease.

21. 4. They harbors a diverse reservoir of antibiotic resistance genes
and this gene can be exchanged between bacteria through
horizontal gene transfer. So they can share drug resistence with
pathogenic bacteria.

22. 5. They can cause disease, especially in immunocompromised
and debilitated individuals. Although these organisms are
nonpathogens in their usual anatomic location, they can be
pathogens in other parts of the body.
.

23. 6. The intestinal bacteria produce several B vitamins and vitamin
K and have a major impact on the absorption of key minerals,
such as iron.
• Gut bacteria aid digestion by breaking down otherwise
indigestable plant fibers into short chain fatty acids that
intestinal cells can access.

24. Microbiome of the intestinal tract

26. • Stomach:
In normal fasting people the stomach contains few organisms,
primarily because of its low PH.

27. • The small intestine:
Streptococci,
lactobacilli, and
yeasts, particularly C.albicans.
(Larger numbers of these organisms are found in the
terminal ileum)

28. • Colon:
Colon is the major location of bacteria in the body. Roughly
20% of the feces consists of bacteria.

30. Microbiome of the skin

31. • Most of them are located superficially in the stratum corneum,
but some are found in the hair follicles and act as a reservoir to
replenish the superficial flora after hand washing.

32. 1. Staphylococcus epidermidis; most predominant organism
(nonpathogen on the skin but can cause disease when it
reaches certain sites, such as artificial heart valves and
prosthetic joints).
2. Staphylococcus aureus.

33. 3. Anaerobic organisms, such as Propionibacterium and
Peptococcus, are situated in the deeper follicles in the
dermis.
(Propionibacterium acnes is a common skin anaerobe that
is causes acne)

34. 4. Candida albicans
( It can enter a person’s bloodstream when needles pierce
the skin, e.g., in patients with intravenous catheters or in
those who use intravenous drugs and may cause systemic
infections in patients with reduced cell-mediated
immunity)

35. Microbiome of the respiratory tract

36. • Nose:
S. aureus
S. epidermidis,
Corynebacterium (diphtheroids),
various Streptococci

37. • Throat:
Viridans streptococci,
Neisseria species,
S. epidermidis.
Various streptococci
Haemophilus influenzae

38. • Mouth:
- Streptococcus viridans make up about half of the bacteria.
1. Streptococcus mutans, found in large numbers in dental
plaque, the precursor of caries.
2. S. sanguinis, causes subacute bacterial (infective) endocarditis,
enter into the bloodstream at the time of dental surgery and
attach to damaged heart valves.

39. - Eikenella corrodens
- Anaerobic bacteria, such as species of Bacteroides,
Prevotella, Fusobacterium, Clostridium, and
Peptostreptococcus, are found in the gingival crevices.(If
aspirated, these organisms can cause lung abscesses, especially
in debilitated patients with poor dental hygiene).

40. • In addition, the gingival crevices are the natural habitat of
Actinomyces israelii, an anaerobic actinomycete that can
cause abscesses of the jaw, lungs, or abdomen.

41. Microbiome of the genitourinary tract

42. • Vaginal:
-Lactobacillus
Lactobacilli are responsible for producing the acid that keeps
the pH of the adult woman’s vagina low. Before puberty and
after menopause, when estrogen levels are low, lactobacilli are
rare and the vaginal pH is high.

43. • Lactobacilli appear to prevent the growth of potential
pathogens, since their suppression by antibiotics can lead to
overgrowth by C. albicans, which can result in Candida
vaginitis.
• The vagina is located close to the anus and can be colonized
by members of the fecal flora. For example, women with
recurrent urinary tract infections harbor organisms such as E.
coli and Enterobacter in the introitus

44. • About 15% to 20% of women of childbearing age carry Group
B streptococci in the vagina. This organism is an important
cause of sepsis and meningitis in the newborn and is acquired
during passage through the birth canal.
• The vagina is colonized by S. aureus in approximately 5% of
women, which predisposes them to toxic shock syndrome.

45. • Various streptococci,
• Various gram-negative rods.
• B. fragilis,
• Corynebacterium (diphtheroids),
• C. albicans

46. • Urethra:
S. epidermidis,
coliforms,
diphtheroids, and
nonhemolytic streptococci.

48. hamimahasnat@yahoo.com