1. NORMAL MICROBIAL FLORA
DR NAZIA KHAN
ASSISTANT PROFESSOR
COLLEGE OF MEDICINE

2. Human beings carry a lot of microorganisms both on and in their body.
A knowledge of normal microbial flora is important to an understanding of the interaction of human beings and their pathogen laden environment.

3. BENEFICIAL FUNCTIONS OF NORMAL FLORA
Prevent colonization by pathogens
Produce antimicrobial substances
In newborn it is a powerful stimulus for the development of the immune system
Microflora of intestine synthesize vitamin k and several B vitamins
Normal flora may produce endotoxins

4. Harmful effects of normal flora
When organisms are displaced from their normal site in the body to an abnormal site
When potential pathogens gain a competitive advantage due to diminished populations of harmless competitors example: by use of antibiotic therapy
When some harmless substances like ingested food are converted into carcinogenic derivatives by bacteria in the colon
Immunocompromised individuals
Drug resistance
Confusion in diagnosis

5. NORMAL FLORA OF THE SKIN
The human skin is constantly bombarded by organisms present in the environment .
It is also contaminated by one’s own secretions and excretions depending on individual’s personal hygiene .
Examples: Staphylococcus
Diphtheroids
E.coli
candida

6. NORMAL FLORA OF THE CONJUCTIVA
It is relatively free from organisms due to the flushing action of tears.
Examples: Diphtheroids
Staphylococcus

7. NORMAL FLORA OF THE NOSE, NASOPHARYNX AND ACESSORY SINUSES
In the nose: Corynebateria
Staphylococcus
The nasopharynx of infant is sterile at birth
But acquires the common commensal flora and pathogenic flora carried form the mother and hospital staff
Examples: Peudomonas
E.coli

8. NORMAL FLORA OF THE MOUTH AND UPPER RESPIRATORY TRACT
Mouth contains many organisms like
Examples: Micrococci
coliforms
Corynebacterium
Fusiform bacilli
Candida
The mouth of the infant is not sterile at birth

9. NORMAL FLORA OF THE INTESTINAL TRACT
In % newborn infants,the meconium is sterile but in 10-20% a few orrganisms probably acquired through labour may be present.
In all cases,within 4-24 hours of birth an intestinal flora is established
In bresstfed children the intestine contains lactobacillus while bottle fed babies have enterococci, colon bacilli and stahpylococci
With the change of food in adult person, flora changes

10. The umber of bacteria increases beyond duodenum to the colon
In adult duodenum there are bacteria per gram
In duodenum and upper ileum, lactobacili and enterococci are present
in adult normal colon,the resident bacterial flora are mostly anaerobes

11. NORMAL FLORA OF THE GENITOURINARY TRACT
Examples: Mycobacterium smegmatitis
In males: lactobacilli,
Female urethra amy be sterile or may have gram positive cocci
The vulva of newborn child is sterile but after 24 hours it acquires many flora
The nature of the flora of the vagina depends on the Ph of its secretions and its enzymes
The normal vaginal flora often includes: anaerobic cocci, and bacilli, listeria,etc.

12. BACTERIA IN THE BLOOD AND TISSUES
Blood is sterile
The commensals from the normal flora of the mouth,nasopharynx and intestinal tract may get into the blood and tissues but they are usually quickly eliminated by the normal defence mechanisms

14. الخميس، 10 محرم، 1440

15. الخميس، 10 محرم، 1440

17. THANK YOU

18. Self assessment
The greatest number and variety of indigenous microflora of the human body live in or on the:
a. colon.
b. genitourinary tract.
c. mouth.
d. skin.
2 . Which of the following sites of the human body does not have indigenous microflora?
a. bloodstream
b. colon
c. distal urethra
d. vagina
3 . Which of the following would be present in highest numbers in the indigenous microflora of the skin?
a. C. albicans
b. coagulase-negative staphylococci
c. Enterococcus spp.
d. E. coli

19. 4. The indigenous microflora of the external ear canal is most like the indigenous microflora of the:
a. colon.
b. mouth.
c. skin.
d. distal urethra.
5. Microorganisms are used in which of the following industries?
a. antibiotic
b. chemical
c. food, beer, and wine
d. all of the above
6. The term that best describes a symbiotic relationship in which two different microorganisms occupy the same ecologic niche, but have absolutely no
effect on each other is:
a. commensalism.
b. mutualism.
c. neutralism.
d. parasitism