Normal flora , microbiology includes the normal flora present in inside the environment and outside the environment and also bacterias etc Normal flora , microbiology includes the normal flora present in inside the environment and outside the environment and also bacterias etc

1. Pharmaceutical Microbiology
Asif Mehmood Hashmi
hashmiajk@yahoo.com
12/13/2022 1

2. Normal Flora

4.  Definition:
Normal flora is the mixture of microorganisms
(bacteria and fungi) that are regularly found at any
anatomical site of human body like:
 Skin
 Eyes (i.e.Cunjunctiva)
 Nose (i.e. Respiratory tract)
 Mouth (i.e. Human Oral Cavity)
 Ears
 Urogenital tract
 Elementary tract

5. In a healthy human, the internal tissues such as:
 blood
 brain
 muscle
 Cerebrospinal fluid
are normally free of microorganisms.

6. Acquired rapidly during & after birth.
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

7. They constitute a protective host defense
mechanism by occupying ecological
niches.
They produce vitamin B and vitamin K
in intestine.
The oral flora contribute to immunity by
inducing low levels of circulating and
secretory antibodies that may cross react
with pathogens.

8. The oral bacteria flora exert microbial
antagonism against nonindigenous
species by production of inhibitory fatty
acids, peroxides, bacteriocins, etc.
The normal flora may antagonize other
bacteria through the production of
substances which inhibit or kill
nonindigenous species.

9. They can cause disease in the
following:
a) When individuals become
immunocompromised or debilitated.
b) When they change their usual anatomic
location.
The oral flora of humans may harm their
host since some of these bacteria are
pathogens or opportunistic pathogens.

10. 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.

11. 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

12.  Normal flora is the term used to describe the
various bacteria and fungi that are permanent
residents of certain body sites, especially the
skin, oropharynx, colon, and vagina.
 The viruses and parasites, which are the two
other major groups of microorganisms, are
usually not considered members of the normal
flora, although they can be present in
asymptomatic individuals.
 The normal flora organisms are often referred to
as commensals (bacterium Staphylococcus
epidermidis uses the dead cells of the human
skin as nutrients).

15. 1.Organisms that are medically
significant or present in large
numbers.
2.Organisms that are less
medically significant or present
in smaller numbers.
3.These organisms are not part of
the normal flora in this location
but are important colonizers.

16.  The predominant organism is Staphylococcus
epidermidis, which is a non-pathogen on the skin
but can cause disease when it reaches certain
sites such as artificial heart valves and prosthetic
joints.
 It is found on the skin much more frequently
than its pathogenic relative Staphylococcus
aureus.
 There are about 103–104 organisms/cm2 of skin.
 Most of them are located superficially in the
stratum corneum, but some are found in the hair
follicles and act as a reservoir to replenish the
superficial flora after hand washing.

17.  Anaerobic organisms, such as Propionibacterium
and Peptococcus, are situated in the deeper
follicles in the dermis where oxygen tension is
low.
 Propionibacterium acnes is a common skin
anaerobe that is implicated in the pathogenesis of
acne.
 The yeast Candida albicans is also a member of
the normal flora of the skin. It can enter a person's
bloodstream when needles pierce the skin (e.g., in
patients with intravenous catheters or in those who
use intravenous drugs).
 It is an important cause of systemic infections in
patients with reduced cell mediated immunity.

18.  A wide spectrum of organisms colonize the nose,
throat, and mouth, but the lower bronchi and alveoli
typically contain few, if any, organisms.
 The nose is colonized by a variety of streptococcal and
staphylococcal species, the most significant of which is
the pathogen S. aureus.
 Occasional outbreaks of disease due to this organism,
particularly in the newborn nursery, can be traced to
nasal, skin, or perianal carriage by health care
personnel.
 The throat contains a mixture of viridans streptococci,
Neisseria species, and Streptococcus epidermidis.

19.  These non-pathogens occupy attachment sites
on the pharyngeal mucosa and inhibit the
growth of the pathogens Streptococcus
pyogenes, Neisseria meningitidis, and S.
aureus, respectively.
 In the mouth, viridans streptococci make up
about half of the bacteria.
 Streptococcus mutants, a member of the
viridans group, is of special interest since it is
found in large numbers (1010/g) in dental
plaque, the precursor of caries.

20.  The plaque on the enamel surface is composed
of gelatinous, high-molecular-weight glucans
secreted by the bacteria.
 The entrapped bacteria produce a large amount
of acid, which demineralizes the enamel and
initiates caries.
 The viridans streptococci are also the leading
cause of bacterial (infective) endocarditis.
 These organisms can enter the bloodstream at
the time of dental surgery and attach to
damaged heart valves.

21.  Eikenella corrodens, also part of the normal oral flora,
causes skin and soft tissue infections associated with
human bites and "clenched-fist" injuries, i.e., injuries
to the hand that occur during fist fights.
 Anaerobic bacteria, such as species of Bacteroides,
Prevotella, Fusobacterium, Clostridium, and
Peptostreptococcus, are found in the gingival crevices,
where the oxygen concentration is very low.
 If aspirated, these organisms can cause lung abscesses,
especially in debilitated patients with poor dental
hygiene.
 In addition, the gingival crevices are the natural habitat
of Actinomyces israelii—an anaerobic Actinomycetes
that can cause abscesses of the jaw, lungs, or abdomen.

22.  In normal fasting people, the stomach contains few
organisms primarily because of its low pH.
 The small intestine usually contains small numbers of
streptococci, lactobacilli, and yeasts, particularly C.
albicans.
 Larger numbers of these organisms are found in the
terminal ileum.
 The colon is the major location of bacteria in the body.
 Roughly 20% of the feces consists of bacteria,
approximately 1011 organisms/g.
 Note that more than 90% of the fecal flora are
anaerobes, the most important of which is Bacteroides
fragilis.

23.  The most abundant facultative bacteria are the
coliforms of which Escherichia coli is the most
important.
 The normal flora of the intestinal tract plays a
significant role in extra intestinal disease.
 For example, E. coli is the leading cause of
urinary tract infections and B. fragilis is an
important cause of peritonitis associated with
perforation of the intestinal wall following
trauma, appendicitis, or diverticulitis.

25. Other important anaerobic pathogens
include Fusobacterium and
Peptostreptococcus and other important
facultative bacteria include Enterococcus
faecalis, which causes urinary tract
infections and endocarditis, and
Pseudomonas aeruginosa, which can cause
various infections, particularly in
hospitalized patients with decreased host
defenses.
P. aeruginosa is present in 10% of normal
stools, as well as in soil and water.

26.  Antibiotic therapy, e.g., with clindamycin, can
suppress the predominant normal flora, thereby
allowing a rare organism such
as the toxin-producing Clostridium difficile to
overgrow and cause severe colitis.
 Administration of certain antibiotics, such as
neomycin orally, prior to gastrointestinal
surgery to "sterilize" the gut leads to a
significant reduction of the normal flora for
several days, followed by a gradual return to
normal levels.

27.  The vaginal flora of adult women consists primarily of
Lactobacillus species.
 Lactobacilli are responsible for producing the acid that
keeps the pH of the adult woman's vagina low.
 Before puberty and after menopause, when estrogen
levels are low, lactobacilli are rare and the vaginal pH
is high.
 Lactobacilli appear to prevent the growth of potential
pathogens, since their suppression by antibiotics can
lead to overgrowth by C. albicans. overgrowth of this
yeast can result in Candida vaginitis.
 The vagina is located close to the anus and can be
colonized by members of the fecal flora.

28.  For example, women who are prone to recurrent
urinary tract infections harbor organisms such as
E. coli and Enterobacter in the introitus.
 About 15% to 20% of women of childbearing age
carry group B streptococci in the vagina.
 This organism is an important cause of sepsis and
meningitis in the newborn and is acquired during
passage through the birth canal.
 The vagina is colonized by S. aureus in
approximately 5% of women, which predisposes
them to toxic shock syndrome.

29.  Urine in the bladder is sterile in the healthy
person, but during passage through the outermost
portions of the urethra it often becomes
contaminated with S. epidermidis, coliforms,
diphtheroids, and nonhemolytic streptococci.
 The area around the urethra of women and
uncircumcised men contains secretions that carry
Mycobacterium smegmatis, an acid-fast
organism.
 The skin surrounding the genitourinary tract is
the site of Staphylococcus saprophyticus, a cause
of urinary tract infections in women.

30.  The air contains gases, dust particles, dried
vapor droplets, in addition to these, air also
contains more number of microorganisms.
 The air has vegetative cells and spores of
bacteria, fungi and algae and protozoan cyst.
 In the atmosphere, air mainly acts as dispersal
or transport medium for microorganisms.
 When compared to soil or water, air contains
less numbers of microorganisms.
 The microbiology of air can be studied under
two headings such as outdoor and indoor micro
flora.

31.  The air in the atmosphere, which is found
outside the buildings, is referred to as outside
air.
 The dominant micro-flora of outside air are
fungi.
 The two common genera of fungi are
Cladosporium and Sporobolomyces.
 Besides these two genera, other genera found
in air are Aspergillus, Alternaria, Phytophthora
and Erysiphe.

32.  The outdoor air also contains basidispores,
ascopores of yeast, fragments of mycelium and
conidia of molds.
 Among the bacterial genera Bacillus and
Clostridium, Sarcina, Micrococcus and
Corynebacterium widely found in the outside
air.
 The number and kind of microorganisms may
vary from place to place, depending upon the
human population densities.

33. The air found inside the building is
referred to as Indoor air.
The commonest genera of fungi in indoor
air are Penicillium, Aspergillus.
The commonest genera of bacteria found
in indoor air are Staphylococci, Bacillus
and Clostridium.

34. The drinking water of most communities
and municipalities is obtained from surface
sources - rivers, streams and lakes.
 Such natural water supplies are likely to be
polluted with domestic and industrial
water.
Many city residents (whose water comes
from the rivers) are not aware that a
considerable portion of their drinking water
may have been used earlier for domestic
and industrial purposes.

35.  Water is used for bathing, washing clothes,
washing utensils and flushing toilets.
 The domestic water consumption may vary with
the availability of water.
 Most of the water taken into the houses may be
returned as waste water through drainage system.
 All these waste waters contain organic and
inorganic waste as suspended or dissolved
matter.
 In addition, these waste waters contain
microorganisms, including those of faecal origin
and pathogenic nature.

36. As a potential of pathogenic organisms,
water can be in danger to health and life.
The pathogens most frequently transmitted
through water are those which cause
infections of the intestinal tract, namely,
typhoid and paratyphoid bacteria, dysentery
(Bacillary) and cholera bacteria and viruses.
The causative organisms of these diseases
are present in the feces or urine of an
infected person.

37. Microorganisms occur in all depths.
The surface film and bottom sediments
have a high concentration of
microorganisms.
 Drifting microbial life of aquatic
environment is called Plankton.
 It is composed of Phytoplankton e.g.
Algae and Zooplankton.

38. The bottom region of the body of water
harbors largest number and kinds of
microorganisms called benthic
microorganisms.
The movement of water by wind, tide and
currents affect the distribution of
microorganisms up welling occurs in
oceans.
 It is a process in which the bottom water
carries with it a rich supply of nutrients and
delivers it to the surface region

39.  Lakes and ponds of temperate region show
thermal stratification, which influences the
microbial population in different seasons.
 In spring and autumn mixing occurs resulting
in massive growth of algae called bloom.
 The common microorganisms found in fresh
water are Pseudomonas, Flavobacterium,
Aeromonas and Alcaligenes.
 It receives fresh water with all particulate
suspensions through rivers.

40.  In areas receiving domestic wastes with
organic nutrients contain the following
organisms: Coliforms, Faecal Streptococci,
Bacillus, Clostridium, Thiothrix and
Thiobacillus.
 Soil bacteria such as Azotobacter,
Nitrosomonas and Nitrobacter are also
found in water.
 Very few fungal organisms from the classes
Ascomycetes, Phycomycetes and Fungi-
imperfecti are also present in water.

41.  The sea is the largest natural environment
inhabited by microbes.
 Bacteria, algae, protozoa, molds and yeast are
major groups of microorganisms found in the sea.
 The number of microorganisms is more in coastal
waters and it gradually decreases in the open sea.
 In sea, phyto-planktons form group of
microorganisms which convert radiant energy into
chemical energy and which support the entire
population of fishes e.g. Diatoms, Cyanobacteria,
Dinoflagellates, Chrysomonads and
Chlamydomonas.

42.  Agriculturally, it is the region supporting plant
life and from which plants obtain their
mechanical support and required nutrients.
 Organic substances.
 The soil environment is unique in several
ways: it contains bacteria, fungi,
Actinomycetes, algae and protozoa.
 It is one of the most dynamic sites of biological
interactions in nature.
 Soil is the region in which occur many of the
biochemical reactions.

43.  The soil is composed of five major components:
mineral matter, water, air, organic matter and living
organisms.
 The quantity of these constituents is not the same in all
soils but varies with the locality.
 The inorganic portion of the soil, because its influence
on nutrient availability, aeration, and water retention
has a marked effect on the microbial inhabitants.
 The soil is not a dead inert material.
 Actually it is full of life.
 One gram of soil contains approximately one million
microorganisms.
 The soil depends upon the microorganisms for its
fertility.

44.  Soils contain five major groups of
microorganisms.
 They are bacteria, actinomycetes, fungi, algae
and protozoa.
 Among the soil microorganisms, bacteria are
most dominant group of organisms.
 All kinds of bacteria are found in the soil.
 This is because all kinds of organic refuse are
disposed off on the soil.

45.  Many of the soil bacteria perform useful
functions like decomposition of organic matter,
conversion of soil constituents into useful
materials, production of antibiotics in the soil,
and biogeochemical cycling of elements like
carbon, nitrogen, phosphorus, iron, sulfur and
manganese.
 The bacterial population of the soil exceeds the
population of all other groups of
microorganisms in both number and variety.

46.  Direct microscopic counts as high as several
billions bacteria per a gram of soil have been
reported.
 The Actinomycetes population as many as
millions per gram of soil is present.
 The most predominant genera present in the soil
are Nocardia, Streptomyces and
Micromonospora.
 These organisms are responsible for the
characteristic musty or earthy odour soon after
the rainfall.

47. Actinomycetes are capable of degrading
many complex organic substances and
consequently play an important role in
building soil fertility.
The Actinomycetes have ability to
synthesize and excrete antibiotics.
Most of the antibiotics are produced by
Actinomycetes.
The presence of antibiotic substances in
soil can be detected with great difficulty.

48.  The fungal population ranging from thousands to
hundred thousands per gram of soil has been reported.
 They are aerobic in nature and found more numbers
near the earth surface.
 They exist in the atmosphere as mycelial and spore
stage.
 Fungi are active in decomposing the major constituents
of plant tissues, namely, cellulose, hemicellulose,
lignin and pectin.
 The population of algae in soil is very smaller than that
of either bacteria or fungi.
 The major types present in the soil are the green algae
and diatoms.

49.  In a fertile soil biochemical activities of algae are
masked by bacteria and fungi.
 In certain conditions, algae perform prominent and
beneficial changes. For example, on barren and
eroded lands they may initiate the accumulation of
organic matter because of their ability to carry out
photosynthesis and other metabolic activities.
 Many soil protozoa are flagellates or amoebas; the
population per gram soil ranges from a few
hundred to several thousand in moist soils rich in
organic matter.
 Protozoa are of significance since their dominant
mode of nutrition involves ingestion of bacteria.