Download Bacteria and Viruses

Bacteria and Viruses
All you ever (didn’t really) want to
know!
Did you know…
You are breathing in bacteria right now
Your body is crawling with bacteria
Right now…
Your skin
Your mouth
Your stomach
Your intestines
(about 500 different species)
Bacteria can grow anywhere
On Earth
Cheese, yogurt and beer are made
With bacteria
Garlic, onion, allspice, hot peppers
And ginger are considered
Anti-bacterial agents
One bacteria cell can become
More than 8 million in 24 hours
A little background on Bacteria
•Bacteria are the only
prokaryotes- What kingdoms?
•They live in soil, water, air, hot
and cold temps
• Bacteria have a cell
membrane that is
surrounded by a tough
cell wall
• DNA is not inside a
nucleus, it floats in the
cytoplasm
• DNA is called a plasmid
• Glycocalyx- polysacc. on
the outside of bacteria to
protect the cell- slimy feel
A square centimeter
of your skin has
Thousands of
bacteria
A teaspoon of soil
contains more than
A billion bacteria
How big are bacteria?
• Bacteria are measured in micrometers- one
millionth of a meter
• Ranging from 1 to 5 micrometers
• Eukaryotic cells tend to be about
10 times larger than a bacterial cell
Bacteria are described according to
their shape
BacilliRod shaped
Cocci- circular shape
Spirilla- spiral shape
Bacterial Nutrition
• Heterotrophic- feed on dead, decaying
organic matter
• Photoautotroph-use sunlight as source of
energy
• Chemoautotroph- use chemical reactions
as a source of energy
• Some bacteria can live with ( aerobic) or
without (anaerobic) oxygen
Production of Toxins
-Bacteria can give off toxins. Toxins are
poisonous substances that disrupt the
metabolism of the infected organism
- endotoxins- found in the cell wall
- exotoxins- secreted into the areas
around the bacteria
Common Bacterial Infections
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Strep throat
Pneumonia
Urinary tract infections
Ear infections
Salmonella and E.coli
Antibiotics
• Inhibit the growth of some bacteria
• They are only used for bacteria, they will not kill viruses (
common cold) For example, an antibiotic might inhibit a
bacterium's ability to turn glucose into energy, or its
ability to construct its cell wall. When this happens, the
bacterium dies instead of reproducing. At the same time,
the antibiotic acts only on the bacterium's cell-wallbuilding mechanism, not on a normal body cells.
• Disadvantages- over use can lead to bacterial resistance
and kill good bacteria in our body
Leading causes of Antibiotic
Resistance
• Antibiotic resistance
Although the survival tactics of bacteria
contribute to antibiotic resistance, humans
bear most of the responsibility for the
problem. Leading causes of antibiotic
resistance include:
Leading causes of Antibiotic
Resistance
• Unnecessary antibiotic use. Like other
superbugs, MRSA is the result of decades
of excessive and unnecessary antibiotic
use. For years, antibiotics have been
prescribed for colds, flu and other viral
infections that don't respond to these
drugs, as well as for simple bacterial
infections that normally clear on their own.
Leading causes of Antibiotic
Resistance
• Antibiotics in food and water.
Prescription drugs aren't the only source of
antibiotics. In the United States, antibiotics
can be found in livestock. These
antibiotics find their way into municipal
water systems when the runoff from
feedlots contaminates streams and
groundwater
Leading causes of Antibiotic
Resistance
• Germ mutation. Even when antibiotics are used
appropriately, they contribute to the rise of drugresistant bacteria because they don't destroy every
germ they target. Bacteria live on an evolutionary
fast track, so germs that survive treatment with one
antibiotic soon learn to resist others. And because
bacteria mutate much more quickly than new drugs
can be produced, some germs end up resistant to
just about everything. That's why only a handful of
drugs are now effective against most forms of staph.
Life Threatening Bacteria
Anthrax
• Anthrax is an acute disease in humans and animals caused
by the bacterium Bacillus anthracis, which is highly lethal in
some forms. There are effective vaccines against anthrax,
and some forms of the disease respond well to antibiotic
treatment.
• The anthrax bacillus is one of only a few that can form longlived spores: in a hostile environment, caused perhaps by the
death of an infected host or extremes of temperature, the
bacteria become inactive dormant spores which can remain
viable for many decades and perhaps centuries. Spores are
found on all continents except Antarctica. When spores are
inhaled, ingested, or come into contact with a skin lesion on a
host they reactivate and multiply rapidly
Anthrax skin lesion
MRSA
• MRSA infection is caused by
Staphylococcus aureus bacteria — often
called "staph." MRSA stands for
methicillin-resistant Staphylococcus
aureus. It's a strain of staph that's resistant
to the broad-spectrum antibiotics
commonly used to treat it. MRSA can be
fatal.
Symptoms of MRSA
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Staph skin infections, including MRSA, generally start as small red bumps that
resemble pimples, boils or spider bites. These can quickly turn into deep, painful
abscesses that require surgical draining. Sometimes the bacteria remain confined to
the skin. But they can also penetrate into the body, causing potentially life-threatening
infections in bones, joints, surgical wounds, the bloodstream, heart valves and lungs.
Flesh Eating Bacteria
• Necrotizing fasciitis is a rare bacterial
infection that can destroy skin and the soft
tissues beneath it, including fat and the
tissue covering the muscles (fascia).
Because these tissues often die rapidly, a
person with necrotizing fasciitis is
sometimes said to be infected with "flesheating" bacteria. The most common type
of bacteria causing necrotizing fasciitis is
Streptococcus pyogenes.
Flesh Eating Bacteria
• To eradicate necrotizing
faciitis, all of the affected
soft tissue must be
removed down to facia,
bone or muscle. Then,
the area must be free of
any bacteria before skin
grafting. The black line
down my shin is the
exposed tibia. The outer
layer of the bone was
killed by the bacteria,
giving it the dark
appearance.
Viruses
• Not considered living!
• They are a biological particle composed of
genetic material and protein
• Consist of RNA or DNA
• Virulent- disease causing
• Temperate- doesn’t cause disease
immediately
• Requires a host cell for reproduction
The Capsid
• Outer shell of the virus particle to protect
the DNA or RNA inside
• Made out of protein
• Can be Icosahedral or Rod Shaped
- A virus is a thousand times
Smaller than a bacteria
- Viruses are found in the
Environment until they find their
Way to a host cell digestive tract
Or respiratory system
- They take over the host cell replication
Machinery and make more virus
How do they replicate?
• The Lytic Cycle
• A virus particle attaches to a host cell.
• The particle releases its genetic instructions into the
host cell.
• The injected genetic material recruits the host cell's
enzymes.
• The enzymes make parts for more new virus
particles.
• The new particles assemble the parts into new
viruses.
• The new particles break free from the host cell
Why We Feel Sick
• An infected person sneezes near you.
• You inhale the virus particle, and it attaches to cells lining the
sinuses in your nose.
• The virus attacks the cells lining the sinuses and rapidly
reproduces new viruses.
• The host cells break, and new viruses spread into your
bloodstream and also into your lungs. Because you have lost
cells lining your sinuses, fluid can flow into your nasal passages
and give you a runny nose.
• Viruses in the fluid that drips down your throat attack the cells
lining your throat and give you a sore throat.
• Viruses in your bloodstream can attack muscle cells and cause
you to have muscle aches.
Our Bodies Response
• Your immune system responds to the infection, and in
the process of fighting, it produces chemicals called
pyrogens that cause your body temperature to increase
•
This fever actually helps you to fight the infection by
slowing down the rate of viral reproduction, because
most of your body's chemical reactions have an optimal
temperature of 98.6 degrees F. If your temperature rises
slightly above this, the reactions slow down.
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This immune response continues until the viruses are
eliminated from your body. However, if you sneeze, you
can spread thousands of new viruses into the
environment to await another host.
The Lysogenic Cycle
• Once inside the host cell, some viruses, such as herpes
and HIV, do not reproduce right away. Instead, they mix
their genetic instructions into the host cell's genetic
instructions.
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When the host cell reproduces, the viral genetic
instructions get copied into the host cell's offspring. The
host cells may undergo many rounds of reproduction, and
then some environmental or predetermined genetic signal
will stir the "sleeping" viral instructions.
• The viral genetic instructions will then take over the host's
machinery and make new viruses as described above
HIV
• HIV infection is a viral infection caused by the human
immunodeficiency virus (HIV) that gradually destroys the
immune system, resulting in infections that are hard for the
body to fight
• People who become infected with HIV may have no
symptoms for up to 10 years, but they can still transmit the
infection to others.
• Meanwhile, their immune system gradually weakens until
they are diagnosed with AIDS.
• HIV infects T-cells- normally the T-cell would kill the virus,
but the virus ends up killing the cell
Vaccines
• Disease prevention is the key to public health. It is
always better to prevent a disease than to treat it.
Vaccines prevent disease in the people who receive
them and protect those who come into contact with
unvaccinated individuals.
• Vaccines help prevent infectious diseases and save
lives. Vaccines are responsible for the control of many
infectious diseases that were once common in this
country, including
• polio, measles, diphtheria, pertussis (whooping cough),
rubella (German measles), mumps, tetanus, and
Haemophilus influenzae type b (Hib), chicken pox.
How they Work?
• Vaccines are preparations that
contain a small portion of a
killed or weakened organism
(often a virus) that we want to
avoid.
• The vaccine is designed to
trigger an immune response to
produce neutralizing
antibodies to the disease
normally caused by this
organism.
• This process then protects us
in the future if exposed to the
genuine bug
Vaccine for Viruses
• Weaken the virus - viruses become unable to
reproduce sufficiently to cause disease, but well
enough to protect against infection in the future.
Measles, Mumps and Chickenpox vaccines are
made this way.
• Inactivate the virus - viruses are completely
killed with a chemical so it cannot reproduce or
cause disease. Polio, Hepatitis A, Influenza and
Rabies vaccines are made this way
Vaccine for Bacteria
• Use a bacterial process - bacteria that cause
disease by producing a toxic protein are
neutralized by inactivating the toxins with a
chemical. Diptheria, Tetanus and Whooping
Cough vaccines are made this way.
• Use part of the bacteria - the vaccine confers
immunity to the sugar coating of the bacteria,
sometimes combined with a harmless protein,
rather than to the bacteria itself. Pneumococcal
and Meningococcal vaccines are made this way.
??Bacteria or Virus??
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Peptidoglycan
Bacteriophage
Sheath
Capsid
Capsule
Glycocalyx
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Plasmid
Bacilli
Icosahedral
Spirilla
Cocci
DNA
DNA & RNA