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Dr.T.V.Rao MD NORMAL HUMAN F L ORA DR.T.V.RAO MD 1

Normal Human Flora

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Normal Human Flora

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Page 1: Normal Human Flora

Dr.T.V.Rao MD

NORMAL HUMAN

FLORA

DR.T.V.RAO MD 1

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HUMAN MICROBIOME

DR.T.V.RAO MD 2

• The human microbiome (or human micro biota) is the

aggregate of microorganisms that reside on the surface

and in deep layers of skin, in the saliva and oral

mucosa, in the conjunctiva, and in the gastrointestinal

tracts. They include bacteria, fungi. Some of these

organisms perform tasks that are useful for the human

host. However, the majority have no known beneficial

or harmful effect. Those that are expected to be

present, and that under normal circumstances do not

cause disease, but instead participate in maintaining

health, are deemed members of the normal flora

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• More bacterial than human cells in the body • provide some nutrients

(vitamin K)

• stimulate immune system, immunity can be cross-reactive against certain pathogens

• Prevent colonization by potential pathogens (antibiotic-associated colitis, Clostridium difficile)

NORMAL BACTERIAL FLORA

DR.T.V.RAO MD 3

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OVERVIEW OF HUMAN-MICROBIAL

INTERACTIONS

• Microbial flora of the healthy human host

1) The reasons for understanding the normal flora of the healthy human body ▶ Normal flora vs. human body ▶ Some normal flora: opportunistic pathogens when injury occurred, when resistance of body decreased, when moved to another site 2) Origin of the normal flora 3) Relationship between normal flora and human host 4) Distribution and occurrence of the normal flora

DR.T.V.RAO MD 4

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5

WHERE TO FIND MICROBE?

EVERYWHERE!

DR.T.V.RAO MD

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INTRODUCTION OF NORMAL FLORA

1. A diverse microbial flora =>

• Human body Area: the skin and mucous membranes

• Time: shortly after birth until death

• Number: 1014 bacteria =>1013 host cells

• 2. Normal flora may:

• a. Aid the host

• b. Harm the host (in sometimes)

• c. Exist as commensals (no effect to the host)

3. Viruses and parasites => NOT normal microbial flora

• Most investigators consider that they are not commensals and do not aid the host.

DR.T.V.RAO MD 6

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Colonization vs. Infection

Colonization: establishment of a site of reproduction of microbes on a person without necessarily resulting in tissue invasion or damage.

Infection: growth and multiplication of a microbe in or on the body of the host with or without the production of disease.

Outcomes of exposure to a microorganism:

1. Transient colonization

2. Permanent colonization

3. Disease

Normal Flora and Pathogenesis

DR.T.V.RAO MD 7

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SIGNIFICANCE OF NORMAL FLORA

• 1.The normal flora influences the anatomy, physiology,

susceptibility to pathogens, and morbidity of the host.

• 2. The effect of the normal flora on the host was not well

• understood until germ-free animals became available.

• Cesarean Section => Germ-free animals => Isolators

w/o detectable pathogens (viruses, bacteria & others)

• 3. Two interesting observations:

• a. the germ-free animals lived almost twice as long as

their conventionally maintained counterparts.

• b. the major causes of death were different in the

• two groups.

DR.T.V.RAO MD 8

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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

DR.T.V.RAO MD 9

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Significance of Normal Flora

Normal flora may aid the host in several ways:

• Aid in digestion of food

• Help the development of mucosa immunity

• Protect the host from colonization with pathogenic microbes.

106

pathogenic

microbes GI infection

w/ normal flora

GI infection

w/ reduced flora after

Streptomycin treatment

10 pathogenic

microbes

DR.T.V.RAO MD 10

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COMPOSITION OF THE NORMAL FLORA

DR.T.V.RAO MD 11

• The normal flora of humans are exceedingly complex and

consist of more than 200 species of bacteria. The makeup

of the normal flora may be influenced by various factors,

including genetics, age, sex, stress, nutrition and diet of the

individual.

Three developmental changes in humans, weaning, the

eruption of the teeth, and the onset and cessation of

ovarian functions, invariably affect the composition of the

normal flora in the intestinal tract, the oral cavity, and the

vagina, respectively. However, within the limits of these

fluctuations, the bacterial flora of humans is sufficiently

constant to a give general description of the situation

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DR.T.V.RAO MD 12

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• A human first becomes

colonized by a normal flora at

the moment of birth and

passage through the birth

canal. In utero, the fetus is

sterile, but when the mother's

water breaks and the birth

process begins, so does

colonization of the body

surfaces. Handling and feeding

of the infant after birth leads to

establishment of a stable

normal flora on the skin, oral

cavity and intestinal tract in

about 48 hours.

WHEN WE GET COLONIZED WITH

NORMAL FLORA

DR.T.V.RAO MD 13

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• The composition of a

child’s bacterial flora

is dependent on the

mother’s micro flora,

since she is the

primary source for

the child’s bacteria

at the outset

A NEW BORN CHILD'S FLORA IS

DEPENDENT ON MOTHER

DR.T.V.RAO MD 14

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• It has been calculated that a

human adult houses about 1012

bacteria on the skin, 1010 in the

mouth, and 1014 in the

gastrointestinal tract. The latter

number is far in excess of the

number of eukaryotic cells in all

the tissues and organs which

comprise a human. The

predominant bacteria on the

surfaces of the human body are

listed in Table 3. Informal names

identify the bacteria in this table.

DENSITY OF NORMAL FLORA IN

HUMANS

DR.T.V.RAO MD 15

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• Resident flora

•Reflects sex

of person

Normal Flora

DR.T.V.RAO MD 16

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POTENTIAL COLONIZATION SITES

DR.T.V.RAO MD 17

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HUMANS AS HABITATS

• Colonization (and infection) frequently begin at mucous membranes

•These are found throughout the body. Consist of single or multiple layers of

epithelial cells, tightly packed cells in direct contact with the external

_____________________________.

Bacteria may

associate loosely

or firmly

Breaches in the

_______________

barrier can result

in infection

(pathogenesis)by

opportunistic

pathogens DR.T.V.RAO MD 18

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UPPER RESPIRATORY TRACT – AND

LOWER RESPIRATORY TRACT

DR.T.V.RAO MD 19

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COMMON SKIN BACTERIUM MAY BE

NEW OPPORTUNISTIC PATHOGEN*

•Helococcus kunzii is a recently identified bacterium that is thought to be a nonpathogenic member of normal human skin flora and is rarely associated with skin infections. In the study though, the researchers report the isolation of the organism from an infected cyst on the breast of a 57-year-old immunocompromised woman.

• Finding provides further support for the opportunistic role of H. kunzii in causing infection in both immunosuppressed and immunocompetent patients," say the researchers. •A.H. Chagla, A.A. Borczyk, R.R. Facklam, and M. Lovgren. 1998. Breast abscess associated with Helocococcus kunzii. Journal of Clinical Microbiology. 36:2377-2379.)

DR.T.V.RAO MD 20

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• E. coli is the best known

bacterium that regularly

associates itself with humans,

being an invariable component of

the human intestinal tract. Even

though E. coli is the most studied

of all bacteria, and we know the

exact location and sequence of

4,288 genes on its chromosome,

we do not fully understand its

ecological relationship with

humans

ASSOCIATIONS BETWEEN HUMANS AND THE

NORMAL FLORA

DR.T.V.RAO MD 21

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• Sometimes the relationship between a member of the normal flora an its host cannot be deciphered. Such a relationship where there is no apparent benefit or harm to either organism during their association is

referred to as a commensal relationship. Many of the

normal flora that are not predominant in their habitat, even though always present in low numbers, are thought of as commensal bacteria. However, if a presumed commensal relationship is studied in detail, parasitic or mutualistic characteristics often emerge.

COMMENSAL RELATIONSHIP.

DR.T.V.RAO MD 22

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NORMAL FLORA ARE MUTUALISTIC

DR.T.V.RAO MD 23

• Much is not known about the nature of the associations between

humans and their normal flora, but they are thought to be

dynamic interactions rather than associations of mutual

indifference. Both host and bacteria are thought to derive

benefit from each other, and the associations are, for the most

part, mutualistic. The normal flora derive from their host a

steady supply of nutrients, a stable environment, and protection

and transport. The host obtains from the normal flora certain

nutritional and digestive benefits, stimulation of the development

and activity of immune system, and protection against

colonization and infection by pathogenic microbes.

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NORMAL FLORA OF THE

GASTROINTESTINAL TRACT (GIT)

• In bottle-fed infants

• Bifidobacteria are not predominant. When breast-fed infants are switched to a diet of cow's milk or solid food, bifidobacteria are progressively joined by:

1. Enterics

2. Bacteroides

3. Enterococci

4. Lactobacilli

5. Clostridia

DR.T.V.RAO MD 24

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NORMAL MICROBIAL FLORA OF THE

GASTROINTESTINAL TRACT

• Functions and Products of Intestinal Flora

• Intestinal microbes carry out a variety of

essential metabolic reactions that produce

various compounds

• The type and amount produced is influenced by the

composition of the intestinal flora and the diet

• Compounds produced include

• vitamins B12 and K

• gas

DR.T.V.RAO MD 25

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DR.T.V.RAO MD 26

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THE FLORA OF THE LARGE INTESTINE

(COLON)

1. Enterococci

2. Clostridia

3. lactobacilli

4. Bacteroides

5. Bifidobacterium (Bifidobacterium bifidum)

6. Escherichia coli

7. Methanogenic bacteria

8. Viridans streptococci

9. Staphylococcus sp.

10. Proteus sp.

11. Candida albicans (Yeast)

12. Mycoplama sp.

DR.T.V.RAO MD 27

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NORMAL FLORA OF THE RESPIRATORY

TRACT

A) The nares (nostrils)

1. Staphylococcus epidermidis

2. Corynebacterium

3. Staphylococcus aureus

4. Neisseria sp.

5. Haemophilus sp

6. Streptococcus pneumoniae

DR.T.V.RAO MD 28

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NORMAL FLORA OF THE RESPIRATORY

TRACT

B) The upper respiratory tract (nasopharynx).

1. Non-hemolytic streptococci

2. Alpha-hemolytic streptococci

3. Neisseria sp.

4. Streptococcus pneumoniae

5. Streptococcus pyogenes

6. Hemophilus influenzae

7. Neisseria meningitidis

DR.T.V.RAO MD 29

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NORMAL FLORA OF THE RESPIRATORY

TRACT

• C) The lower respiratory tract (trachea, bronchi, and pulmonary tissues):

• Usually sterile.

• The individual may become susceptible to infection by pathogens descending from the nasopharynx e.g.

• H. influenzae

• S. pneumoniae).

DR.T.V.RAO MD 30

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NORMAL FLORA OF THE HUMAN ORAL

CAVITY

• Oral bacteria include:

1. Viridans streptococci

2. Lactobacilli

3. Staphylococci (S. aureus and S. epidermidis)

4. Corynebacterium sp.

5. Bacteroides sp.

6. Streptococcus sanguis (dental plaque)

7. Streptococcus mutans (dental plaque)

8. Actinomyces sp.

DR.T.V.RAO MD 31

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SITES OF HUMAN BODY THAT THE NORMAL

FLORA

MICROBES COLONIZE

• 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

DR.T.V.RAO MD 32

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• Especially in hosts

rendered susceptible by:

• 1. Immuno-suppression

(AIDS & SCID)

• 2. Radiation therapy &

Chemotherapy

• 3. Perforated mucous

membranes

• 4. Rheumatic heart

disease…etc.

NORMAL FLORA MAY ACT AS

OPPORTUNISTIC PATHOGENS

DR.T.V.RAO MD 33

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Sterile tissues

In a healthy human, the

internal tissues such as:

• blood

• brain

• muscle

• cerbrospinal fluid (csf.)

are normally free of

microorganisms.

Normal Flora absent in …

DR.T.V.RAO MD 34

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1. They constitute a

protective host

defense

mechanism

by occupying

ecological niches.

Importance of The Normal Flora

(Advantages)

DR.T.V.RAO MD 35

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NORMAL FLORA OF THE SKIN

• The most important

sites are:

1. Axilla

2. Groin

3. Areas between the

toes

DR.T.V.RAO MD 36

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The oral flora contribute to immunity by inducing low levels of circulating and secretory antibodies that may cross react with pathogens.

IMPORTANCE OF THE NORMAL FLORA

(ADVANTAGES)

DR.T.V.RAO MD 37

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1. They can cause disease in the following:

a) When individuals become immunocompromised or debilitated.

b) When they change their usual anatomic location.

IMPORTANCE OF THE NORMAL FLORA

(DISADVANTAGES)

DR.T.V.RAO MD 38

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FECAL BACTERIOTHERAPY

DR.T.V.RAO MD 39

• Fecal bacteriotherapy, which is now officially and

scientifically known as fecal micro biota

transplantation and is also referred to as fecal micro

biota therapy, fecal transfusion, fecal transplant, stool

transplant, fecal enema or human probiotic infusion

(HPI), is a medical treatment for patients with

pseudomembranous colitis (caused by Clostridium

difficile), or ulcerative colitis that involves restoration of

colon homeostasis by reintroducing normal bacterial

flora from stool obtained from a healthy donor.

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• Fecal micro biota transplantation

(FMT) -- also known as fecal

bacteriotherapy, among other names

-- is an effort to calm a troubled

bowel by reintroducing the vast

diversity of collaborative bowel

inhabitants after the usual mix has

been disturbed. More than 1,000

different strains of bacteria co-

exist peacefully in the typical healthy

bowel. But when the delicate

balance is altered, by antibiotics or

other causes, a few strains can

become dominant, leading to severe

diarrhea, inflammation and tissue

damage.

FECAL MICRO BIOTA

TRANSPLANTATION

DR.T.V.RAO MD 40

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• Like an organ transplant, fecal

microbiota transplantation begins

with finding a donor, often a

family member. The treatment

team collects a fresh stool

sample, at least 200 to 300

grams. The sample is mixed with

salt water in a blender and

filtered to remove particulate

matter. It can be administered to

the recipient through a

colonoscopy, as an enema, or --

when the inflamed region is

higher in the colon -- through a

naso-gastric tube.

MICROBIOTA TRANSPLANTATION

DR.T.V.RAO MD 41

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• Programme created by Dr.T.V.Rao MD for

Medical and Paramedical students in the

Developing World • Email

[email protected]

DR.T.V.RAO MD 42