The document discusses the normal flora or microbiota that colonize the human body. It describes the major sites where microbes normally reside, including the skin, respiratory tract, gastrointestinal tract, and urogenital tract. The gut microbiota plays an important role in digestion and produces vitamins. Antibiotics can disrupt the normal balance of microbes. The Human Microbiome Project aims to characterize the microbes associated with health and disease.

1. Micro
of the human body
Semester -6th
Paper – Medical-
microbiology
Topic – Normal flora
BY: KHAN SHAH RUKH
Roll no : 4181457022
Submitted to: Dr. Sweta

2. Introduction of normal flora
Factors influencing normal flora
Distribution of the normal flora
Normal flora – skin
Normal flora- upper respiratory tract
Normal flora-gastrointestinal tract
Normal flora-urogenital tract
Significance of the normal flora
Human microbiome project
Summary
Reference
Questions
CONTENT

3. Microbes are all over us
http://commons.wikimedia.org/wiki/File:Man_shadow_-_upper.png
Thousands of different species on the skin
alone
Some thrive on dry patches of the elbow,
others thrive in moist environment of
armpit
There are millions of microbes
per square inch on your body
It is estimated that there are more microbes
in your intestine than there are human cells
in your body!

5. Germ-free Animals Regular
Counterparts
Lifespan Twice One
Cause of
death
Intestinal Atonia Infection
Anatomic &
Physiological
Changes
1. Alimentary lamina
propria under-
developed
2. No Ab
3. Intestinal epithelial cell
renewal rate down
half
Germ-free Animals vs Counterparts

11. 1. Local Environment (pH,
temperature, redox
potential, O2, H2O, and
nutrient levels…).
2. Diet
3. Age
4. Health condition (immune
activity…)
5. Antibiotics,…..etc
Factors Influencing Normal Flora

12. Microbes are normally found in and on
the human body
The followingsitesare “hotspots” for microbial life
http://nihroadmap.nih.gov/hmp/ Let’s explore these regions
Some
microbes are
native,
normally
found in the
body
Some microbes
are introduced,
suddenly arriving
at a new
residence in the
body

13. Respiratory tract and head
outer ear, eye, mouth, oropharynx, nasopharynx
Sterile sites: sinuses, middle ear, brain, lower
respiratory tract (trachea, bronchiole, lung)
Gastrointestinal tract
esophagus, stomach, small intestine, large intestine
Genitourinary system
anterior urethra, vagina
Sterile sites: bladder, cervix, uterus
Skin
Sites of human body that the normal flora
microbes colonize

14. Normal flora - Skin

16. What’s Happening
on the Skin?
There are several skin
environments: oily,
dry, moist. Some
microbes prefer one
over another.
The skin has natural
defenses including
slightly acidic sweat
and antimicrobial
peptides.
Microbes hide in
crevices to recolonize
skin after washing with
soap
Antibiotic washes and
oral antibiotics disturb
normal balance of
microbes on the skin
There is a normal balance of microbes on the skin that protect introduced microbes
from harming us. Damaged skin gives opportunities for microbes to invade the
bloodstream and cause serious illness.

17. Skin
• Propionibacterium acnes bacteria colonizes healthy pores, but if pores
become clogged, it grows out of control
• Staphylococcus epidermidis bacteria normally colonizes on the skin. But
when P. acnes clogs pores, S. epidermidis also grows out of control in the
infected pores
• Staphylococcus aureus bacteria can also infect clogged pores like Staph
epidermidis. Even worse, many antibiotic resistant strains of Staph
aureus make it difficult to treat the infection.

18. Normal Flora- Upper RespiratoryTract

19. Figure27.11
Sinuses
Nasopharynx
Pharynx
Oral cavity
Larynx
Trachea
Bronchi
Lungs
Upper
respiratory
tract
Lower
respiratory
tract
© 2012 Pearson Education, Inc.

20. Nose
The interior lining of the nose contains mucous secreting glands. A wide
variety of microbes are normally found there. Here’s a few:
http://commons.wikimedia.org/wiki/File:Human-nose.jpg
http://en.wikipedia.org/wiki/File:Staphylococcus_epidermidis_01.pn
g
• Staphylococcus epidermidis bacteria forms a biofilm
that coats the mucosal lining
• Staphylococcus aureus bacteria is fine when kept
under control by a protease found in S. epidermidis,
but if left to grow out of control, S. aureus can become
pathogenic and cause infection
http://en.wikipedia.org/wiki/File:MRSA7820.jpg
What’s Happening
in the Nose?

21. Nose
http://commons.wikimedia.org/wiki/File:Human-nose.jpg http://en.wikipedia.org/wiki/File:Aspergillus_fumigatus_Invasive_Disease_Mechanism_Diagram.jpg
• Aspergillus fungal spores are often
inhaled through the nose. If the
immune system fails to clear these,
mold can grow in the lungs
http://en.wikipedia.org/wiki/File:Aspergillus.jpg
• Corneybacterium accolens bacteria is rarely a
pathogen, but if it enters the bloodstream due to a
torn blood vessel, it can cause serious infections
http://en.wikipedia.org/wiki/File:Corynebacterium_ulcerans_01.jpg

22. Normal flora
Gastrointestinal tract

23. Figure27.9
Major bacteria present Organ
Esophagus
Stomach
Small
intestine
Large
intestine
pH 2
Secretion of acid (HCl)
Digestion of macromolecules
pH 4–5
Continued digestion
Absorption of monosaccharides,
amino acids, fatty acids, water
pH 7
Absorption of bile acids,
vitamin B12
Duodenum
Jejunum
Ileum
Colon
Anus
Esophagus
Lactobacilli
Enterococci
Prevotella
Streptococcus
Veillonella
Helicobacter
Proteobacteria
Bacteroidetes
Actinobacteria
Fusobacteria
Bacteroides
Bifidobacterium
Clostridium
Enterobacteria
Enterococcus
Escherichia
Eubacterium
Klebsiella
Lactobacillus
Methanobrevibacter
(Archaea)
Peptococcus
Peptostreptococcus
Proteus
Ruminococcus
Staphylococcus
Streptococcus
Major physiological
processes
© 2012 Pearson Education, Inc.

25. What’s Happening
in the Gut?
http://commons.wikimedia.org/wiki/File:Intestine_and_stomach_-_transparent_-_cut.png
Major barriers for microbes entering the gut:
• low pH
• Saliva and Bile
• Immune system
• Finding a place to attach to intestinal wall
• Surviving a widely varied diet
For those microbes that manage to colonize the gut:
• gut flora perform regular tasks of digestion, vitamin production, many others

26. Gut
http://commons.wikimedia.org/wiki/File:Intestine_and_stomach_-_transparent_-_cut.png
http://microbewiki.kenyon.edu/index.php/File:G_reaction1.jpg
Ruminococcus sp. bacteria can be found in significantly
high numbers in the gut flora. They break down cellulose
in the gut, helping with digestion.
Helicobacter pylori bacteria has a helical shape and colonizes the
stomach and upper G.I. tract. It is known to be a major cause of
stomach ulcers, although many with H. pylori do not get ulcers.
http://commons.wikimedia.org/wiki/File:Helicobacter_pylori_diagram.png

27. Normal Flora-Urogenital Tract

28. Alpha hemolytic streptococci
anaerobes streptococci (peptostreptococci)
Provotella
Clostridium
Gardnerella vaginalis
Uriplasma urilyticum
NORMAL FLORA -VAGINA
MOST COMMON BACTERIA LEAST COMMON BACTERIA
Lactobacillus sp
Streptococcus sp.
Alpha hemolytic Streptococci,
Anaerobes Streptococci,
(Peptostreptococci )
Provotella sp.,
Clostridia sp.,
Gardnerella sp,.
Uriplasma urealyticum,
Sometimes Listeria sp. and
Mobiloncus sp.

29. Urogenital
http://commons.wikimedia.org/wiki/File:Female_Genital_Organs.svg
Lactobacillus and vaginal epithelial cell
http://commons.wikimedia.org/wiki/File:Lactobacillus_sp_01.png
Lactobacillus
normally maintain
low pH while
other species are
kept in small
numbers in the
vagina
If
Lactobacillus
decreases from
antibiotics…
Candida
albicans can
take over and
cause a yeast
infection
http://en.wikipedia.org/wiki/File:Candida_albicans_2.jpg
G. vaginalis and vaginal epithelial cell
Gardnerella
vaginalis can grow
too much and cause
bacterial vaginosis.

30. Interplay Between Medicine
and Microbes
Antibiotics
Kills infectious bacteria but also
disrupts natural flora. Can result in
yeast infections, digestive problems,
etc.
http://commons.wikimedia.org/wiki/File:NOVAMOXIN_antibiotic.jpg
http://commons.wikimedia.org/wiki/File:Chemotherapy_bottles_NCI.jpg
Chemotherapy drugs
Gut flora has been shown to modify
some drugs during metabolism. This
causes many side effects, including
upset stomach.

34. Normal flora may act as opportunistic
pathogens
Especially in hosts rendered susceptible by:
1. Immuno-suppression (AIDS & SCID)
2. Radiation therapy & Chemotherapy
3. Perforated mucous membranes
4. Rheumatic heart disease…etc.

35. From friends and foe

36. Possible questions that may be answered
by the HMP
How stable and resilient is an individual’s microbiota
throughout one day and during his/her lifespan?
How similar are microbiomes between members of a family,
community or across communities in different
environments?
Do all humans have an identifiable “core” microbiome and
how is it acquired and transmitted?
What affects the genetic diversity of the microbiome and
how does this diversity affect adaptation by the
microrganism and the host to markedly different lifestyles
and to various physiological or pathophysiological states?

37. Goals
New diagnostic biomarkers of health
Industrial application
Deeper understanding of nutritional requirements of
humans
Personalized drug and diet regimen

38. Future Research
Better coverage needed for shotgun sequencing.
Also new experimental approach should be created
which allow the sequencing of the more fragile phyla of
bacteria, such as bacteroitides.
Analyses of horizontal gene transfers in gut microbes.
Quantitation of metabolites etc, contributed and
consumed by gut flora.
Effects of antibiotic administration of gut flora and the
host, succesion of microbes after antibiotics, and
creation of pathogenic specific antibiotics that don’t
effeect the gut flora or at least minimalize effects.

39. SUMMARY

42. • Should a doctor consider a patient a single human organism
or a community of organisms?
• What is the community of the human host and its microbes
called?
• Where on a healthy human is the microbiome located?
• Does your body contain more of your own human cells or
more microbial cells?
Comment on the normal flora of the gut and its significance?
(2015)
Name any two bacteria inhabiting the skin?(2014)
Questions?

43. Reference
 Jawetz, Melnick, & Adelberg’s,Medical Microbiology,
Twenty-Sixth Edition
Google search-slide share.com
wikipedia.com
and
https://www.google.co.in/?gfe_rd=cr&ei=0avdVa3RI6TG8Aeb3p
,
https://www.google.co.in/?gfe_rd=cr&ei=0avdVa3RI6TG8Aeb3p
https://www.google.co.in/search?sclient=psy-ab&site=&source=
1c.1.64.psy-ab..13.0.0.0.rM6dRZ_quqc&pbx=1 .
http://commons.wikimedia.org/wiki/File:Lactobacillus_sp_01.png

44. In the womb, humans are free of microbes. Colonization begins during the journey down
the birth canal, which is riddled with bacteria, some of which make their way onto the
newborn's skin.