A presentation on microflora or microbiota.

1. HUMAN MICROBIAL FLORA
 Yasidi M. b.

2. LEARNING OBJECTIVES
What ARE normal FLORA
RESIDENT AND TRANSIENT FLORA
BENEFITS OF NORMAL FLORA
HARMFUL EFFECTS OF NORMAL FLORA

3. Introduction
The Human microbiome (normal flora) is an aggregate
of microorganisms that reside on the surface or deep
layers of the skin and mucous membranes, They include
bacteria and fungi some of which are beneficial to man
while some are harmful. Normal flora are symbiotic
either as opportunistic, commensalistic or mutualistic in
nature.

4. NORMAL MICROBIAL FLORA
The term “ normal microbial flora”
denotes the population of microorganisms
that inhabits the skin and mucous
membranes of an healthy normal
individuals

5. SYMBIOSIS
symbiosis
opportunistic
mutualistic
commensalistic

6. • Under normal condition they do not
cause harm, but if conditions become
favourable they strive.
Opportunistic
• Both organisms benefit from the
relationships.
Mutualistic
• One organism benefit, while the
other neither benefit nor harmed.
Commensalistic

7. FACTORS THAT INFLUENCES THE ACTIVITIES
OF NORMAL FLORA
Temperature
Oxygen
Redox Potential
Anatomical sites
moisture
Nutrients
pH.
Immune status

8. Microbiome or normal flora of the skin or
mucosal surfaces are:-
Residents: these are fixed aggregate
groups of microbes that regularly inhabit a
given anatomical site at a given age, if
disturbed they re-establish themselves.
Transient: these are nonpathogenic or
potentially pathogenic microbes that
inhabit the skin or the mucosal surfaces for
hours, days or weeks, if disturbed they
don’t re-establish themselves.

9. MERITS OF MICROBIAL FLORA
Protect the host’s defence system by
maintaining conditions such as pH.
Compete for nutrients with pathogenic
organisms.
Compete for colonization with pathogenic
organisms & immune stimulation
They synthesize vitamin B, K and ammonia.
Inhibit the growth of pathogenic bacteria by
secreting waste substances.

11. DEMERITS OF FLORA
Can cause infections if they change
anatomical site. E.g. E.coli
Can cause infection if he immune
system is compromised. E.g.
pseudomonas
Can cause infections if conditions favors
their growth
Transfer to susceptible host
Compete for host’s nutrients

12. NORMAL FLORA OF THE SKIN
The skin harbors largely the resident flora
which include:-
o S. epidermidis
o Diphtheriods
o Propionibacterium
o Peptostreptococci
o Staphylococcus aureus
o Non-pathogenic Neisseria

13. FACTORS THAT KEEP SKIN FLORA IN CHECK
Skin is slightly acidic with pH of 4-6 due to the
organic acid produce by microorganisms and
secretions from sweat gland.
Lack of moisture on the skin drive resident flora in to
a dormant state.
High concentrations of salt in sweat makes the skin
hyperosmotic which suppress the growth of some flora
Lysosomes from sweat gland is inhibitory to some
organisms

14. FLORA OF THE ORAL CAVITY
The oral cavity is also a
habitat to collection of
microorganisms :-
Viridans streptococci
Lactobacilli
Corynebacterium sp.
Bacteriods.
Actinomycetes.

15. THE NASAL FLORA
The nasal systems also harbors
collection of microbiomes which
include:-
S. epidermidis
Corynebacterium
S. aureus
Haemophilus sp.
Neisseria sp.
S. pneumonia.

16. FLORA OF THE RESPIRATORY TRACT
The upper respiratory tract is
colonized by normal flora
 Beta and alpha hemolytic
streptococcus
 Neisseria sp.
 H. influenza.
Lower respiratory tract do not have
normal flora

17. INTESTINAL FLORA
The intestine harbors lot of bacteria
mostly during adult stage.
At birth the intestine is sterile, but
organisms are soon introduce through
food.
The number of microbiomes outnumber
the human somatic cells.
Concentration of 10PM12/gram in colon
Total weight: 1-2kg

18. URETHRAL FLORA
The anterior portion of the urethra of
both sexes inhabits numbers of types
bacteria found skin and perineum and
are normally voided in urine.

19. VAGINAL FLORA
The soon after birth, aerobic lactobacilli
appear in the vagina and persist for several
weeks because is acidic.
Mixed flora of cocci and bacilli strive till
puberty stage because is now neutral
At puberty stage aerobic and anaerobic
lactobacilli reappear in large number to
maintains the acid pH.
These checks the presence of pathogens.

20. VAGINAL FLORA CONT.
If lactobacilli are suppressed due to
administration of drugs, yeasts and other
bacteria strive and causes irritation.
After menopause, lactobacilli diminishes and
mixed flora returns.
Group B streptococci are acquired during birth
which might in some cases causes sepsis.
They include : Streptococci, Prevotella,
Clostridia, Ureaplasma, Gardnerella, Listeria

21. CONJUNCTIVAL FLORA
Predominantly the diphtheriods, S. epidermidis,
and nonhemolytical streptococci occupies the
conjunctiva.
Neisseria and gram-negative bacilli resembling
haemophili are also present.
The conjunctival flora are kept under check by the
flow of tears which contain antibacterial
lysosomes

22. THANKS