All Time Service Available Call Girls Marine Drive 📳 9820252231 For 18+ VIP C...
Microbial flora-of-the-human-body
1. Dr. Rashad Shawgi Babiker
M.Sc. (Microbiology) (UMST)
M.Sc. Stud. (Immunology )
Institute of Tropical Medicine.(SAS)
2. Normal Flora
Definition
Normal flora is the
mixture of
microorganisms
(bacteria and fungi) that
are regularly found at
any anatomical site of
human body.
3.
4. Symbiotic Relationship
1. Mutualistic
Both organisms benefit – “mutually benefical”
2. Commensalistic
One organism benefits, the other is neither helped nor
harmed
3. Opportunistic
Under normal conditions, microbe does not cause
disease, but if conditions become conducive , it can
cause disease
6. Commensalistic
We have no Commensalistic relationships with Bacteria
If Bacteria are in or on our body, they are either helping
us (Microbial Antagonism) or harming us.
7. Opportunistic
Escherichia coli - normally in our digestive tract
where it causes no problems, but if it gets into the
urinary tract it can become pathogenic.
Staphylococcus aureus – commonly found in the
upper respiratory tract, but if it gets into a wound or a
burn it can become pathogenic
9. Normal Microbial Flora
1. Resident Flora
Microbes that are always present
2. Transient Flora
Microbes that live in or on your body for a period of time
(hours, days, weeks, months) then move on or die off
10.
11. Transient Microbiota
Remain in the body for only hours to
months before disappearing
Found in the same regions as resident
microbiota
Cannot persist in the body…because…
Competition from other microorganisms
Elimination by the body’s defenses cells
Chemical or physical changes in the body
12. Sterile tissues
In a healthy human, the
internal tissues such as:
blood
brain
muscle
cerbrospinal fluid (csf.)
are normally free of
microorganisms.
Normal Flora
13. Normal Flora
Skin
Eyes (i.e.Cunjunctiva)
Nose (i.e. Respiratory
tract)
Mouth (i.e Human Oral
Cavity)
Ears
Urogenetal tract
Elementry tract
15. Normal Flora
Resident flora
Reflects age of person
Changes continuously
through out life
Reflects nutrition of
person
Reflects genetics of
person
Reflects environment of
person
Reflects sex of person
16. 1. They constitute a
protective host
defense mechanism
by occupying
ecological niches.
Importance of The Normal
Flora (Advantages)
17. Importance of The Normal Flora
(Advantages)
2. They produce vitamin B
and vitamin K in
intestine.
18. Importance of The Normal Flora
(Advantages)
3.The oral flora
contribute to
immunity by inducing
low levels of
circulating and
secretory antibodies
that may cross react
with pathogens.
19. Importance of The Normal Flora
(Advantages)
4.The oral bacteria flora
exert microbial
antagonism against
nonindigenous species
by production of
inhibitory fatty acids,
peroxides, bacteriocins,
etc.
20. Importance of The Normal Flora
(Advantages)
5. The normal flora may
antagonize other
bacteria through the
production of
substances which inhibit
or kill nonindigenous
species.
21. Importance of The Normal Flora
(Disadvantages)
1. They can cause disease in
the following:
a) When individuals
become
immunocompromised.
b) When they change their
usual anatomic location.
22. Contamination vs. Infection
Contamination – the mere presence of microbes in or
on the body
Infection – results when the organism has evaded the
body’s external defenses, multiplied, and become
established in the body
23. Portals of Entry
Sites through which pathogens enter the body
Four major types
Skin
Mucous membranes
Placenta
Parenteral route
24. Skin
Outer layer of packed, dead, skin cells
usually acts as a barrier to pathogens
Some pathogens can enter through
openings or cuts
Others enter by burrowing into or
digesting the outer layers of skin…
flesh-eating bacteria
25. Mucous Membranes
Line the body cavities that are open to
the environment
Provides a moist, warm environment
that is hospitable to pathogens
Respiratory tract is the most commonly
used site of entry – entry is through the
nose, mouth or eyes
Pathogens able to survive the acidic pH
of the stomach may use the
gastrointestinal tract as a route of entry
28. Infection vs. Disease
Infection is the invasion of the host by a pathogen
Disease results only if the invading pathogen alters the
normal functions of the body
Disease is also referred to as morbidity
29. Manifestations of Disease
Symptoms – subjective characteristics of disease felt
only by the patient
Signs – objective manifestations of disease that can be
observed or measured by others
Syndrome – group of symptoms and signs that
characterize a disease or abnormal condition
Asymptomatic, or subclinical, infections lack
symptoms but may still have signs of infection
30. Etiology
Study of the cause of disease
Germ theory of disease – disease caused by infections of
pathogenic microorganisms
Robert Koch developed a set of postulates one must
satisfy to prove a particular pathogen causes a
particular disease