Normal flora refers to the microorganisms naturally found in different areas of the human body. These microorganisms include bacteria and fungi found in places like the skin, respiratory tract, mouth, and ears. The normal flora varies depending on factors like a person's age, nutrition, environment, and health status. While normal flora play an important role in occupying niches and producing vitamins, they can also cause disease if the person becomes immunocompromised or the microorganisms shift locations. Examples of normal flora include Staphylococcus epidermidis and Staphylococcus aureus on the skin and Corynebacterial and Neisseria species in the respiratory tract. The gastrointestinal tract fl

1. NORMAL FLORA
By Sikander Ali
WhatsApp number: +923369179410 Gmail: sikanderalisumalani11@gmail.com

2. what is normal flora
 Normal flora is the mixture of
microorganisms (bacteria and
fungi) that are regularly found at
any anatomical site of human body
 They are found in areas like: skin,
respiratory tract, mouth, ears.

3. Attribute of Normal flora:
Reflects age of person
Changes continuously throughout life
Reflects nutrition of person
90% is S. epidermidis; S. aureus, may be in moist areas
Reflects environment of person

4. Sterile tissues:
In a healthy human, the internal tissues such as blood,
brain, muscle, cerebrospinal fluid (CSF) are normally
free of microorganisms.

6. Advantages/Disadvantages of the normal
flora:
Advantages of the normal flora: Disadvantages of the normal flora:
1. They constitute a protective host defense
mechanism by occupying ecological niches.
2. They produce vitamin B and vitamin K in
intestine. E.g. E.coli
3. The normal flora may antagonize other bacteria
through the production of substances which
inhibit or kill non-indigenous species.
1. They can cause disease in the following:
i. When individuals become
immunocompromised.
ii. When they change their usual anatomic
location.
2. The oral flora of humans may harm their host
since some of these bacteria are pathogens or
opportunistic pathogens.

7. 1. Normal Flora of the Skin:
The most important sites are: perineum, toe webs, hands, face, trunk,
upper arms and legs.
The majority of skin microorganisms are found in the most superficial
layers of the epidermis and the upper parts of the hair follicles.
• Important bacteria:
o Staphylococcus epidermidis:
____Major inhabitant making up more than 90% of the flora.
o Staphylococcus aureus:
____Nose, perineum, vulvar skin.
____Occurrence in nasal passages varies with age being greatest in
newborns, less in adults

8. 2. Normal flora of the respiratory tract
The nares (nostrils) contains,
1. Staphylococcus epidermidis
2. Corynebacterial
3. Neisseria sp.

9. 3. Normal flora of the gastrointestinal
tract (GIT)
• In humans, the GIT flora is influenced by: age, diet, cultural conditions
and the use of antibiotics
At birth:
___The entire intestinal tract is sterile, but bacteria enter with the first
feed. The initial colonizing bacteria vary with the food source of the infant.
In bottle-fed infants:
___Bifidobacterial are not predominant. When breast-fed infants are
switched to a diet of cow's milk or solid food, bifidobacterial are
progressively joined by: Enterococci, Bacteroides, Staphylococci,
Lactobacilli and Clostridia

10. Probiotics/Prebiotics:
Probiotic :
It is the oral administration of living organisms to promote health
__Mechanism speculative: competition with other bacteria; stimulation of
nonspecific immunity
__Species specific: adherence and growth (tropism)
Prebiotic:
__It is the Non-digestible food that stimulates growth or activity of GI
microbiota, especially bifidobacterial and lactobacillus bacteria (both of
which are noninflammatory)