Download Antibiotic Resistant Bacteria

Viruses, Bacteria
Diversity of Life
Today…
• Viruses
• Prokaryotes
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VIRUSES
Viruses are non-living organisms.
Technically they are not considered living organisms,
since they cannot self replicate (they’re not a kingdom)
Remember that living organisms:
1.
2.
3.
4.
5.
6.
7.
8.
Organized (have cells)
Maintain homeostasis
Take energy & use it
Respond to stimuli
Grow & develop
Able to self reproduce (sexually or asexually)
Have Genetic material
Adapt to their environments
Virus structure
• Viruses: Just a protein coat
for protection (capsid) and a
nucleic acid (RNA or DNA) for
information on how to make
more copies of the same virus
• Cannot replicate/reproduce on
its own! Needs a host…
Virus is a cellular parasite
• Uses cell machinery of a host cell to
replicate and to produce more viruses
• They come in
many varieties,
sizes & shapes
Viruses cause diseases
• Viruses cause numerous diseases in Plants, animals,
bacteria & fungi…
• Examples of human viruses:
• Herpes virus
• Hepatitis virus
• Rabies
• Ebola – emerging epidemics
• Influenza (“flu”) – respiratory infection (fever, headache,
chills, cough, stuffy nose, sore throat) caused by a variety
of viruses. Flu season: Nov. – March.
• Passed on by sneezing, coughing – air, hand-to-mouth,
etc.
• Vaccine helps prevent outbreaks.
Human Viruses
• Human Immunodeficiency Virus (HIV) – causes
AIDS.
• Transmitted through
sexual contact,
sharing infected needles,
blood transfusions,
mother to baby.
• Severe Acute Respiratory Syndrome (SARS) –
brand new deadly virus, started in China, causes
atypical pneumonia. Spreads quickly.
• Antibiotics Don’t Work but some do have
antiviral medication.
Plant Viruses
• Tobacco Mosaic Virus (TMV) causes
mottling symptoms
• Rose mosaic virus
• Spots on fruit
• Wheat stunt virus
Genetic Reassortment in Influenza Viruses
Generation of Novel Influenza A Viruses
Human H2N2
ANTIGENIC SHIFT
Genetic Reassortment
Avian H3N8
Point mutation of HA and NA
genes
ANTIGENIC DRIFT
Human H3N2
Virus-induced tumours
Virus
Infection
[ ]
Uninfected
Cell
Uncontrolled cell
growth and tumour
formation
Infected cell
PROKARYOTES
• Bacteria are small and unicellular
• They have no internal
organelles
(no chloroplasts, nucleus,
ER, mitochondria)
Bacteria
• Replication is asexual – clonal, rapid simple
division (no mitosis)
• Pseudo-sexual reproduction, has means for
Genetic exchange
• Called conjugation
Bacteria
• Bacterial forms: cocci, bacilli, spirilli
• Some forms are photosynthetic: cyanobacteria
Bacterial pathogens
• Animal pathogens:
• Typhoid, tuberculosis
• Bubonic plague or “Black Death”,
transmitted by fleas (caused
25 million deaths in Medieval
Europe)
• Syphilis, gonorrea (venereal diseases)
• E. coli, Salmonella (food poisoning)
76 million illnesses worldwide
Some examples of contagious bacterial diseases are:
-strep throat
-impetigo
-pertussis (whooping cough)
-bacterial conjunctivitis (pink
eye)
Antibiotics Work
Bacterial control
• There are ways of controlling bacterial
growth:
• Disinfectants
• Antibiotics
• Low temperatures
• High temperatures,
• Low oxygen
Beneficial Bacteria
• Nitrogen-fixation – convert atmospheric N into
useful Nitrogen (N gas  plants  animals)
• Decomposition in the biosphere – get rid of dead
organisms, nature’s recyclers
• Intestinal Bacteria – supply vitamins (K)
• Commercial use: yogurt, sour cream, fermentation
• Genetically-engineered bacteria produce insulin
and other important chemicals.
• Can also help clean up oil spills: oil ‘eating’
bacteria!
What are
Antibiotics?
Powerful medicines with one very important job: to
fight disease-causing bacteria.
When used properly, antibiotics can save lives.
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Antibiotic Resistant
Bacteria Are:
Bacteria that mutate and are able to resist
the antibiotics that are meant to kill them.
This is a normal process speeded up by
the overuse and misuse of antibiotics.
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What is Antibiotic Misuse?
• Taking antibiotics when they are not needed:
– for viral infections
• When needed, taking antibiotics incorrectly:
– stopping the medicine when you feel better - not
finishing the prescription
– saving antibiotics for a future illness
– sharing or using someone else’s medicine
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Why is Antibiotic Misuse
a Problem?
1. Antibiotics become less effective and may not
work the next time you use them.
2. Improper use of antibiotics leads to more
antibiotic resistant bacteria.
3. Antibiotic resistant bacteria can be spread
throughout the community and from person to
person.
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Antibiotic Resistant Bacteria
• Require stronger antibiotics
• Are more common in people who recently
used antibiotics*
• Can be spread within a family or a
community
• Can affect anyone
• Are becoming more common
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Emergence of Antimicrobial
Resistance
Susceptible Bacteria
Resistant Bacteria
Resistance Gene Transfer
New Resistant Bacteria
Selection for AntimicrobialResistant Strains
Resistant Strains
Rare
Antimicrobial
Exposure
Resistant Strains
Dominant
This process shows what?
Can Disease affect a population
or evolution?
Can Disease affect a population
or evolution?
1. Small pox introduction to Native Americans
2. Sickle- Cell anemia advantages to being heterozygous
Populations decrease with
pathogens.
What if a few are resistant to
disease?
How do we fight them?
• Sanitation and safe water
• Antiviral- kill/suppress viruses
Our Immune System
• First line of defense:
skin, tears, stomach acid
• Second line of defense:
Inflammation – white
blood cells, temp.
increases (fever not so
bad!)
Antigens and Antibodies
• Antigen – is the substance that triggers a
response: pollen, bacterial toxin, virus
• Antibodies – Proteins that recognize and bind
to antigens (shaped like the letter Y)
– Produced by B cells
– Travel through the blood
– Can “remember” antigens
Vaccines:
Vaccine helps prevent outbreaks.
•Our bodies use introduced antigens to make antibodies to
fight the disease in the future.
•What are advantages to this?
Passive Immunity: Receive
antibiodies from mother (birth or
breast milk)
Active Immunity: You make
antibodies on your own from getting
sick or vaccine