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Bacteria and Viruses

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Bacteria and Viruses Powered By Docstoc
					H5 avian flu virus.
       About 17 million birds
        were slaughtered in the
        Fraser Valley in February
        2004 following an
        outbreak of the H7N3
        strain of the disease, but it
        was a different strain from
        the deadly H5N1 version
        linked to nearly 250
        deaths and other illnesses
        in Southeast Asia, China,
        Russia and Europe.
                  Animal Cell
   Complex
   Many
    specialized
    organelles
   Nucleus
    surrounded
    by
    membrane
    Bacteria
   Tiny single celled
    organisms
   Differ from plant and
    animal cells in that
    they have no nuclear
    membrane
   Some organelles
Viruses
   Much smaller than
    bacterium
   Protein coat and
    genetic material
    (DNA or RNA)
                Bacterial Shapes
   Cocci
       spheres
   Monococcus
       Single sphere
   Diplococcus
       Live in pairs
   Streptococcus
       Chains of spheres
   Staphlococcus
       Grape-like clusters
Streptococcus
Staphlococcus
              Bacterial Shapes
   Bacilli
       Rod shaped
   Streptobacillus
       ?
   Staphlobacillus
       ?
                 Bacterial Shapes
   Spirillium
       Spiral or cork-screw
        shaped
       Bacterial Reproduction
   Bacteria contain the genetic
    blueprint (DNA) and all the tools
    (ribosomes, proteins, etc.) they
    need to reproduce themselves
   Reproduce through binary fission
   May exchange genetic material
        Bacterial Reproduction
   E. coli bacteria,
    found in the gut can
    divide    every   20
    minutes - this could
    yield 72 generations
    per day -that's 40
    with 21 zeros after it
    bacteria.
Bacteria Named by Shape
            Pathogenic Bacteria
   Clostridium
    botulinum
       Botulism is the result
        of an exotoxin
        produced by this
        anaerobe
Staphlococcus - Grape-like clusters
             ―Boils‖
            Pathogenic Bacteria
   Staphylococci
       Part of normal fauna
        of face and nose
        skin infections, boils
        and pimples but a
        virulent strain may
        cause death
Streptococcus - Chains of spheres
         ―Strep Throat‖
            Pathogenic Bacteria
   Streptococci
       strep throat, scarlet fever (caused by the
        bodies immune reaction) rheumatic heart
        disease
       Necrotizing fasciitis
           Pathogenic Bacteria
   Treponema pallidum
       syphilis spirochaete
            Pathogenic Bacteria
   Nesseria
    gonorrhoeae
       diplococcus
        gonorrhoea,      very
        resistant strains to
        antibiotics     have
        recently evolved
              Pathogenic Bacteria
   E. coli
       Normal inhabitant of the gut of many animals and
        birds
       Indicator of fecal contamination of water and food
       Escherichia coli O157:H7 (more than 70,000 a
        year infected in USA)
       http://www.sciencenews.org/20010804/bob12.asp
Plaque



   Tooth decay is the destruction
    of the outer surface, or enamel,
    of a tooth. It is caused by acid
    buildup from plaque bacteria,
    which dissolve the minerals in
    the enamel and create cavities.
                Antibiotics
   Bacterial infection can be directly
    treated through the use of antibiotics.
   The action of these drugs is varied but
    many interfere with bacterial
    reproduction.
   Remember E. coli with 72 generations
    per day
Penicillin – the first antibiotic
   1928 Alexander Fleming was growing
    staphylococci bacteria that he had isolated
    from wounds on agar plates.
   Became contaminated
Penicillin
   identified the fungus as Penicillium
    notatum
   Was unable to stabilize penicillin
   1940 Ernst Chain isolated and purified
    penicillin and human trials began
   Penicillin kills bacteria by interfering
    with the ability to synthesize cell wall.
Penicillin
   Before the introduction of penicillin
    many people died from bacterial
    infections
   How many times have you taken an
    antibiotic?
   It probably saved your life.
Antibiotics produced by Bacteria

   they are produced by some bacteria to
    prevent other bacteria from growing
    near them and using up their food
   Tetracycline
   Streptomycin
   Erythromycin
   How do
    antibiotics
    interfere with
    bacterial
    reproduction?
Biofilms
   Biofilms — snotty sheets of goo made by
    bacterial colonies — may be the secret
    superpower of the microbial world. When
    bacteria are deeply encased in a biofilm, they
    don't grow or reproduce. Since antibiotics work
    by disrupting those same activities, such
    bacteria are nearly invincible. Biofilms might be
    behind the tenacity of chronic ear infections
    and even tuberculosis.
Ancient Life
   The cyanobacteria or "blue-green
    algae," have left a fossil record that
    extends far back into the Precambrian -
    the oldest cyanobacteria-like fossils
    known are nearly 3.5 billion years old,
    among the oldest fossils currently
    known.
short chain of cyanobacterial
cells, from the Bitter Springs
Chert of northern Australia (about
1 billion years old).




            living
            cyanobacterium
      Cyanobacteria
   Many oil deposits are attributed to the activity of
    cyanobacteria
   The oxygen atmosphere that we depend on was
    generated by numerous cyanobacteria
   The chloroplast with which plants make food for
    themselves is actually a cyanobacterium living within
    the plant's cells
Women have a greater range of different
types of bacteria on the palms of their
hands than men, US research from the
University of Colorado at Boulder
suggests.




    http://news.bbc.co.uk/2/hi/health/7705608.stm
              Tuesday, 4 November 2008
   Using powerful gene sequencing
    techniques, researchers found a typical
    hand had roughly 150 different species
    of bacteria living on it.
   The study detected and identified more
    than 4,700 different bacteria species
    across 102 human hands in the study.
   However, only five species were shared
    among all 51 participants.
•   Even the right and left palms of the same
    individual shared an average of only 17%
    of the same bacteria types.
•   On average, women had 50% more
    bacterial species on their hands than men.
•   The higher bacterial diversity on women's
    hands may be due to the fact that men
    tend to have more acidic skin, which
    provides a more harsh living environment
    for the microscopic bugs.
•   Dr Fierer said the study also found hand
    washing had little impact on the diversity of
    bacteria found on an individual's hands.
•   While some groups of bacteria were less
    abundant following hand washing, others were
    more abundant.
•   However, the researchers said that washing
    with anti-bacterial cleansers was still an
    effective way to minimise the risk of disease, as
    it seemed particularly to target harmful bugs.
   Most are likely to be neutral, just living
    there without doing any harm or good.
   It is thought that having such flora on
    our hands is probably beneficial,
    because the bacteria occupy niches
    which are then unavailable to
    pathogens.
                     Prions
   Prions are rather ill-defined infectious
    agents believed to consist of a single
    type of protein molecule with no nucleic
    acid component.
   These agents are associated with
       Kuru and Creutzfeldt-Jakob disease in
        humans
       scrapie in sheep
       bovine spongiform encephalopathy (BSE) in
        cattle.
   The diseases are not caused by a
    bacterium—or a virus—or anything
    containing nucleic acid. They appear to
    be caused by nothing more than a
    misfolded protein, called a prion
    (proteinaceous infectious only;
   2). In addition, prions can apparently
    cross species barriers.
   BSE is unlike many other food-borne
    pathogens in that it cannot be killed
    simply by cooking the infected meat.

    Milk and milk products from cows are
    not believed to pose any risk for
    transmitting the BSE agent.
BSE
   In 1986, BSE (bovine spongiform
    encephalopathy or ―mad cow disease‖),
    a prion disease of cattle was described
    in England.
   The symptoms in affected cattle
       rapidly changed behavior
       inability to stand
       reduced sensation.
   When the epidemic peaked in 1993, an
    estimated 1.2 million animals were possibly
    infected, and the meat of about 730,000 BSE-
    infected cows had entered the human food
    chain
   Exports of beef from the United Kingdom
    were halted, and entire herds of cattle were
    destroyed to prevent the spread of the
    disease. The economic cost was huge.
         Bovine Spongiform
          Encephalopathy
   It was on September 10, 2001, that
    mad cow disease began a crisis in the
    North American beef industry.
   Japan reported its first case of bovine
    spongiform encephalopathy.
   People in Japan stopped eating beef!
Impact on Canada
   Canada has close to 13.5 million cows and calves.
    About 5.7 million (or 42 per cent) are in Alberta.

   Canada's total beef exports amount to $2.2 billion
    annually, and have risen sharply in recent years.
    Since 1991, beef exports have risen from 100,000
    tonnes to about 500,000 tonnes. Growth in exports
    has been greatest to Japan, South Korea and Mexico.
    Alberta's share of total beef exports is 39 per cent
    (worth about $860 million a year).
Kuru
   The disease was the
    result of the practice
    of ritualistic
    cannibalism among
    the Fore,people of
    New Guinea in which
    relatives prepared
    and consumed the
    tissues (including
    brain) of deceased
    family members.
Creutzfeldt-Jakob Disease
   First, the disease can occur sporadically,
    i.e. without apparent cause.
   Second, the disease can be inherited.
    10 – 15 % of cases
    Third, the disease can be transmitted
    through infection
Symptoms of CJD
   The initial stage of the disease can be
    subtle with ambiguous symptoms of
    insomnia, depression, confusion,
    personality and behavioral changes,
    problems with memory, coordination
    and sight.
Symptoms of CJD
   As the disease advances, the patient
    experiences a rapidly, progressive
    dementia
   involuntary and irregular jerking
    movements
   Problems with language, and sight,
    muscular weakness, and coordination
Symptoms of CJD
   In the final stage of the disease, the
    patient loses all mental and physical
    functions. The patient may lapse into a
    coma and usually dies from an infection
    like pneumonia precipitated by the
    bedridden, unconscious state.
Treatment of CJS
   At the present time, there is no known
    effective treatment to arrest or cure
    CJD. The disease is inevitably fatal.
   The only treatments available for CJD
    patients focus on easing their
    symptoms and discomfort.

				
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