Normal flora by MR. MANOJ MAHATO j

1. NORMAL FLORANORMAL FLORA
MR. MANOJ MAHATOMR. MANOJ MAHATO

2. NORMAL FLORA
• DefinitionDefinition
Normal flora is the mixture ofNormal flora is the mixture of
microorganisms (bacteria and fungi)microorganisms (bacteria and fungi)
that are regularly found at anythat are regularly found at any
anatomical site of human bodyanatomical site of human body
on /within the body of a healthyon /within the body of a healthy
personperson

3. NORMAL FLORA
oSkinSkin
o Eyes (i.e.Cunjunctiva)Eyes (i.e.Cunjunctiva)
o Nose (i.e. Respiratory tract)Nose (i.e. Respiratory tract)
o Mouth (i.e Human OralMouth (i.e Human Oral
Cavity)Cavity)
o EarsEars
o Urogenetal tractUrogenetal tract
o Gastrointestinal tractGastrointestinal tract
 LOCATION SITE OF NORMAL FLORA ON HEALTHY PERSONLOCATION SITE OF NORMAL FLORA ON HEALTHY PERSON

4. ORIGIN OF NORMAL FLORAORIGIN OF NORMAL FLORA
Healthy fetus, in utero, is essentially free of MOsHealthy fetus, in utero, is essentially free of MOs
Infant exposed immediately to MOs when passingInfant exposed immediately to MOs when passing
through mom’s vaginal tract and then to MOs inthrough mom’s vaginal tract and then to MOs in
environmentenvironment
Within few hours, oral and nasopharyngeal flora ofWithin few hours, oral and nasopharyngeal flora of
neonate establishedneonate established
Within one day, resident flora of lower intestinalWithin one day, resident flora of lower intestinal
tract establishedtract established

5. TYPES OF NORMAL FLORATYPES OF NORMAL FLORA
• 1. Resident Flora
• Microbes that are always present
• consists of relatively fixed types of microorganisms regularly
found in a given area at a given age
• If disturbed, it promptly reestablishes itself
• 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
• consists of nonpathogenic or potentially pathogenic
microorganisms that inhabit the skin or mucous membranes for
hours, or days

6. FACTORS INFLUENCING THE NORMAL FLORA
Acquired rapidly during & afterAcquired rapidly during & after birth
Changes continuously through out lifeChanges continuously through out life
1.1.Local EnvironmentLocal Environment
2.2.DietDiet
3.3.AgeAge
4.4.SexSex
5.5.Immune conditionImmune condition
6.6. Use ofUse of Antibiotics

7. .
FACTORS INFLUENCING NORMAL FLORA
 Nutrition of personNutrition of person
 Age of personAge of person

8.  Genetics of personGenetics of person
FACTORS INFLUENCING NORMAL FLORA
 Sex of personSex of person

9. FACTORS INFLUENCING NORMAL FLORA
 EnvironmentEnvironment:
- pH, temperature, redox
potential, O2, H2O
-90% is S. epidermidis; S. aureus,
may be in moist areas

10. NORMAL FLORA
STERILE TISSUES:STERILE TISSUES:
In a healthy human, the internal tissues such as:
-Blood
-Brain
-Muscle
-Body Fluid
-Cerbrospinal fluid (csf.)
are normally free of microorganisms

11. Importance of The Normal Flora- Advantages
-Because of the normal flora occupy
body’s epithelial surfaces, they are
able to prevent other bacteria from
establishing themselves by blocking
receptors (attachment), competing for
essential nutrients or producing anti-
bacteria substances.
e.g.Fatty acids, peroxides , Bacteriocins
1.Protection from External Enviornment1.Protection from External Enviornment

12. Importance of The Normal Flora- Advantages
2. NUTRITION2. NUTRITION
•They produce vitamin B12 and vitamin K in intestine.
-E. coli & Bacteroids produce Vitamin K in the gut which is
available for use by host.

13. Importance of The Normal Flora- Advantages
3.3. IMMUNOSTIMULATIONIMMUNOSTIMULATION
a)They produce antibodies which may
contribute to host defenses.
b)Some of these antibodies may cross
react with normal tissue components.
.

14. Importance of
TheNormalFlora(Advantages)
4. Inhibitory action:4. Inhibitory action:
The noral bacteria flora exert microbial
antagonism against nonindigenous species
by production of inhibitory fatty acids,
peroxides, bacteriocins, etc.

16. Importanceof The Normal Flora(Disadvantage
1. They can cause disease in the
following:
a) When individuals become
immunocompromised
b) When they change their
usual anatomic location.

17. Importance of TheNormalFlora(Disadvantage)
2.The oral flora of humans may harm their
host since some of these bacteria are
pathogens or opportunistic pathogens

18. Estimation of the Normal flora
• It has been calculated that the
normal flora human body about
1012
bacteria on the skin, 1010
in
the mouth, and 1014
in the
gastrointestinal tract.

19. Normal Flora of the Skin
• The most important sites are:
1. Axilla
2. Groin
3. Areas between the toes

20. Normal Flora of the Skin
• The majority of skin microorganisms
are found in the most superficial layers
of the epidermis and the upper parts of
the hair follicles.

21. Normal Flora of the Skin
• Important bacteria:
1. Staphylococcus epidermidis
2. Micrococcus sp.
3. Corynebacteria sp.
4. Mycobacterium smegmatis

22. Normal Flora of the Conjunctiva
1. Staphylococcus epidermidis
2. Corynebacterium sp.
3. Propoinibacteriumacnes)
4. Staphylococcus aureus
5. Viridans streptococci
6. Neisseria sp.
7. Haemophilus influenzae

23. Normal flora - Conjunctiva
• low numbers present due to
•High moisture
•Blinking mechanically removes
bacteria
•Lachrymal secretions include
lysozyme

24. Pathogens which do infect the conjunctiva
• Neisseria onorrhoeae
• Chlamydia trachomatis

25. Sinuses
Nasopharynx
Pharynx
Oral cavity
Larynx
Trachea
Bronchi
Lungs
Upper
respiratory
tract
Lower
respiratory
tract
ANATOMY OFANATOMY OF RESPIRATORY TRACT

26. Normal Flora of the Respiratory Tract
A) The nares (nostrils)
1. Staphylococcus epidermidis
2. Corynebacteria
3. Staphylococcus aureus
4. Neisseria sp.
5. Haemophilus sp
6. Streptococcus pneumoniae

27. 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. Haemophilus influenzae
7. Neisseria meningitidis

28. Normal Flora of the Respiratory Tract
C) The lower respiratory tract:
- Trachea, bronchi, and pulmonary
tissues are usually sterile due to:
• Ciliated epithelium
• Mucus blanket: entrapment
• Alveolar macrophages
• If breached: opportunistic infections
occurs when individual may become
susceptible to infection by pathogens
descending from the nasopharynx
e.g. H. influenzae, S.pneumoniae).

29. Sputum SampleSputum Sample

30. Normal Flora of the Human- Oral Cavity
• Ecology and developmental stages:
• Birth: sterile mouth within 4-12 hours: lactobacilli,
streptococci
• Neonate : (Streptococcus salivarius, staphylococci,
Neisseriae, Moraxella catarrhalis
• Teeth appear: Streptococcus mutans, Streptococcus
parasanguis
• Gingival crevice area: Anaerobic species, yeasts
• Puberty: Bacteroides, spirochetes
• 108
bacteria/mL of saliva; potentially >700 species

31. Normal flora - Urogenital tract
Upper urinarytract: kidneys,ureters,bladder are usually
sterile
•Male anterior urethra: Same as skin
+enteric+enterococcus
•Vagina: complex microbiota
•At birth: Same as mother (PH 5)
•Neonate: Same as skin+enteric+ strept (PH 7)
•At puberty: Lactobacillus+same as
skin+anaerobes+strep (PH 5)
•At menopause: return to prepuberty flora

32. VAGINAL FLORAVAGINAL FLORA

33. The Normal Flora of The Ears (external ear)
The external ears contains avariety of
microorganisms.
These include:
1. Staphylococcus epidermidis
2. Staphylococcus aureus
3. Corynebacterium sp

34. Normal flora of the Urogenital Tract
a) The anterior urethra:
1. Staphylococcus epidermidis
2. Enterococcus faecalis
3. lpha-hemolytic streptococci.
4. Some enteric bacteria (e.g. E. coli, Proteus sp.)
5. Corynebacteria sp.
6. Acinetobacter sp.
7. Mycoplasma sp.
8. Candida sp.
9. Mycobacterium smegmatis

35. Normal flora of the Urogenital Tract
b) The vagina
1. Corynebacterium sp.
2. Staphylococci
3. Nonpyogenic streptococci
4. Escherichia coli
5. Lactobacillus acidophilus
6. Flavobacterium sp.
7. Clostridium sp.
8. Viridans streptococci
9. Other Enterobacteria

36. Normal Flora of the Gastrointestinal Tract
In humans, the GIT flora are
influenced by:
1. Age
2. Diet
3. Cultural conditions
4. The use of antibiotics

37. Normal Flora of the Gastrointestinal Tract
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.

38. Normal Flora of the Gastrointestinal Tract
In breast-fed
1. Bifidobacteria account for more
than 90% of the total intestinal
bacteria.
2. Enterobacteriaceae
3. Enterococci
4. Bacteroides
5. Staphylococci
6. Lactobacilli
7. Clostridia

39. Normal Flora of the Gastrointestinal Tract
 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

40. Normal Flora of the Gastrointestinal Tract
In the upper GIT of adult humans
• mainly acid-tolerant lactobacilli
e.g. Helicobacter pylori
H. pylori survives in the submucosal layer

41. Normal Flora of the Gastrointestinal Tract
The proximal small intestine
1. Lactobacilli
2. Enterococcus faecalis
3. Coliforms
4. Bacteroides

42. THE FLORA OF THE LARGE INTESTINE
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.

43. BACTERIAL-HUMAN RELATIONSHIPS
-Normal flora
-Opportunistic infections
-Pathogenic infections

44. NORMAL FLORA - RISKS
Dental plaque
Dental caries: destruction of enamel,
dentin or cementum of teeth
Periodontal disease
Inflammatory bowel disease
Obesity

45. OPPORTUNISTIC FLORA
Some normal flora become opportunistic pathogens
(Staphylococcus aureus, Streptococcus mutans, Enterococcus
faecalis, Streptococcus pneumoniae, Pseudomonas aeruginosa,
etc.)
Breach of skin/mucosal barrier: trauma, surgery, burns
Bacterium at one site may be commensal, but might be pathogenic at
another site

46. Mouth flora

47. OPPORTUNISTIC FLORA
 -Growth of commensals may put patient at risk
 -Broad-spectrum antibiotic therapy decreases total number of
bacterial in gut
 -During repopulation, faster-growing aerobic Enterobacteriaceae
over slower-replicating anaerobes increases probability of gram-
negative bacteremia
 -Cross-reactive responses to host tissue: Superantigen ,Chronic,
low-grade inflammation,Perturbation of cytokine network

48. OPPORTUNISTIC FLORA onon GASTROINTESTINAL
Due to overuse of Antibiotics
•Antibiotic associated diarrhae
•C. dfficile -associated diarrhea
(CDAD)
•Pseudomembranous colitis
•toxic megacolon

49. NORMAL FLORA - RISKS AND OPPORTUNISTIC

50. PROBIOTICS/PREBIOTICS
 PROBIOTICPROBIOTIC
Oral administration of living organisms to promote health
Mechanism speculative: competition with other bacteria;
stimulation of nonspecific immunity
Species specific: adherence and growth (tropism)
 PREBIOTICPREBIOTIC
Non-digestible food that stimulates growth or activity of GI
microbiota, especially bifidobacteria and lactobacillus bacteria
Typically a carbohydrate: soluble fiber