Transcript Normal and Transient Flora. Host Parasite

Normal and Transient Flora;
Host/Parasite Relationships
Microbial Ecology

The study of microorganisms and their
environment.
www-esd.lbl.gov
Symbiosis
“living together”
 Describes the interactions that occur
between two dissimilar organisms (usually
2 different species) that live together or are
in close association with one another.
 Symbionts
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the organisms that live together in such a
relationship.
Neutralism
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Symbiotic relationship in which neither
symbiont is affected by the relationship.
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Both species are unaffected.
Commensalism
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Symbiotic relationship in which one symbiont
benefits and the other species is not affected
(neither harmed nor helped).
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Ex. Propionibacterium
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many species in this genera live on the skin and are thought to
neither hurt nor help humans.
Host
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An organism that harbors another organism.
Mutualism
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Symbiotic relationship
that is beneficial to
both symbionts.
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Ex. Termites and
protozoa
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Ex. Lichens

Termite
Lichen.
botit.botany.wisc.edu
Ex. Some species of
our microflora (i.e.
Escherichia coli.)
E. coli.
www3.niaid.nih.gov
Parasitism

Symbiotic relationship
in which one symbiont
is benefited and the
other is harmed.
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Ex. Sheep liver fluke
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Ex. Opportunistic
pathogens of our
normal flora.
Sheep Liver Fluke.
locksparkfarm.wordpress.com
Synergistic Relationship

When two (or more)
microorganisms “team
up” to cause a disease that
neither could cause by
itself.
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Called synergistic
infections.
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Ex. Acute necrotizing
ulcerative gingivitis (i.e.
“Trench Mouth).
Acute necrotizing
ulcerative gingivitis.
www.ohiohealth.com
Normal Flora of Humans

All microbes that reside on
and within a person.

Most commonly inhabited
parts of the body.
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Eyes
Skin
Mouth
Ears
Upper respiratory tract
Gastrointestinal tract
Genitourinary tract
www.scq.ubc.ca
When do microorganisms take up
residence in humans?
Establishing Normal Flora
www.ehponline.org
www.solarnavigator.ne
Transient Flora
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Live temporarily on the body.
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Often “picked up” from our daily routines.
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Why are they temporary?
Importance of Normal Flora
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Often helps prevent
infection.

Prolonged use of
antibiotics can cause an
imbalance.

Candida albicans.
www.humanillnesses.com
Ex. Candida albicans
Candida albicans
infection. www.lib.uiowa.edu
Microflora of the Skin
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Consists of mostly bacteria and fungi.
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Most are anaerobes, although some are
aerobic.
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Anaerobes live in the:
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deeper layers of the skin
hair follicles
sweat and sebaceous glands
health.howstuffworks.com
Microflora of the Skin
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The number and variety of microorganisms
depends on the:
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Amount of moisture present
pH
Temperature
Salinity
Presence of chemical wastes such as urea and fatty
acids
Presence of other microbes (which may produce
toxic substances)
Groups of Normal Skin Flora
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1. Diphtheroids (Coryneforms)
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2. Staphylococcus spp.
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Gram-positive, non-spore forming
rods.
Ex. Propionibacterium acnes.
Gram-positive cocci usually arranged
in clusters.
Helps maintain normal flora balance.
Propionibacterium acnes.
bacteriality.com
3. Yeasts – Candida spp.
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Single-celled fungi.
Ex. Causes tinea versicolor.
Tinea versicolor.
georgiahealthinfo.gov
Microflora of the Eyes and Ears
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Ears
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Middle ear and inner ear
sterile.
Outer ear and auditory canal
contain same types of
microorganisms as are found
on the skin.
www.bluedothealth.com
Eyes
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Does contain some
microorganisms.
Tears, mucus, and sebum
that are produced in and
around the eye greatly
reduce many
microorganisms.
www.infovisual.info
Respiratory Tract
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Upper Respiratory Tract
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Nasal passages
Throat (pharynx)
Lower Respiratory Tract
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Larynx (voice box)
Trachea
Bronchi
Bronchioles
Lungs
www.uic.edu
Microflora of the Respiratory Tract
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Upper Respiratory Tract
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Nasal Passages and Throat
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Have many species of microorganisms.
Provide moist, warm environment.
Many are harmless.
Some are opportunistic pathogens.
Some people are carriers of virulent pathogens.
Lower Respiratory Tract
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Usually microbe free.
Microflora of the Upper Respiratory Tract
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Staphylococcus spp.
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S. aureus
Corynebacterium spp.
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Gram-positive cocci in clusters.
Often includes S. aureus.
Gram-positive rods; nonmotile; nonspore-forming.
Nonpathogenic species.
Collectively called diphtheroids.
Moraxella spp.
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Corynebacterium spp.
Gram-negative diplococci.
Resemble Neisseria species.
Moraxella spp.
Microflora of the Upper Respiratory
Tract cont.
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Haemophilus spp.
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H. influenzae
Bacteroides spp.
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Small, gram-negative rods.
Often includes H. influenzae.
Small, gram-negative rods.
Strict anaerobes.
Streptococcus spp.
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Bacteroides fragilis
Gram-positive streptococci in chains.
Often includes S. pneumoniae.
Streptococcus spp.
Microflora of the Oral Cavity
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Provides great shelter and
nutrients for many species of
microbes.
Flourish in gum margins,
crevices between teeth, and
deep fold of the tonsils.
Bacteria feed on food particles
and dead epithelial cells.
Poor hygiene can lead to
periodontal diseases.
Most common microbes are
species of alpha-hemolytic
streptococci.
anatomy.med.umich.edu
Gastrointestinal Tract
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Digestion of food,
absorption of nutrients, and
elimination of undigested
material.
 Includes:
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Oral cavity and throat (already
discussed)
Esophagus
Stomach
Small intestines
Large intestines
Anus
www.giconsults.com
Microflora of the Gastrointestinal Tract
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Stomach
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Small Intestine
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Acidic environment prevents much growth.
Exception – Helicobacter pylori – found in some people causes
ulcers.
Upper part of small intestine (duodenum) – little growth due to
bile.
Lower portion of small intestine (jejunum and ileum) – more
microbial growth present.
Large intestine (colon)
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Contains the largest number and variety of microbes.
500-600 species.
Anaerobic environment.
Contains obligate anaerobes, aerotolerants, and facultatives.
Many are opportunistic pathogens if enter other areas of the
body.
Genitourinary Tract
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Urinary Tract
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Kidneys
Ureters
Urinary bladder
Urethra
Male and Female
Reproductive
Systems
www.pvurology.org
Microflora of the Genitourinary Tract
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Healthy kidneys, ureters, and urinary bladder are
sterile.
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Urethra harbors many microbes (i.e. yeasts, bacteria, and
viruses).
Usually don’t invade bladder due to acidic nature of urine.
UTI (urinary tract infections) occur when microbes travel up
the urethra and multiply.
Male and female reproductive systems are sterile
with the exception of the vagina.
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Type of growth depends on stage of sexual development.
pH of vagina changes throughout sexual development
providing different environments for different organisms.
The End