Download 3.1 Bacteria and Viruses

Bacteria and
Viruses
Prokaryotes
• Prokaryotes (from Old Greek pro- before + karyon- nucleus) are
organisms without a cell nucleus or any other membrane-bound
organelles.
• Most are unicellular, but some prokaryotes are multicellular.
• Prokaryotes have had a greater impact on the environment and
on biological evolution than all other forms of life combined.
Prokaryotic cells contain pili, a cell wall, capsule, and ribosomes,
but no membrane-bound nucleus.
• Prokaryotes are classified into two domains, Bacteria and
Archaea.
• Viruses are sometimes discussed in this category since they are
neither prokaryotic nor eukaryotic, but more closely resemble
prokaryotes.
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ARCHAEA
• Archaea are microscopic organisms which
thrive in places too acidic, too salty, too cold,
or too hot for most other organisms.
Archaea are one of the most
abundant cell types below
1,000 meters in the oceans.
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ARCHAEA
• 1. Methanogens: Use carbon dioxide for energy and make methane gas
(flatulence) as a waste product. They cannot survive in an oxygen
environment. They can live in animal bodies such as humans, cattle, and
termites. Human intestinal gas is largely produced by Archaea in our
intestines. Some live in swamps where the other microorganisms have
used up all the oxygen, and they create “marsh gas”. They are used as
decomposers in sewage treatment facilities.
• 2. Extreme Halophiles: like excess salt; some live in the Great Salt Lake
and the Dead Sea.
• 3. Extreme thermophiles: like extreme temperatures (hot and cold).
Examples are those living in sulfur-rich volcanic springs at 300°F, and the
hot springs of Yellowstone National Park. Others live in the freezing
temperatures of the deep sea or the Antarctic regions.
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BACTERIA
• Bacteria thrive almost everywhere; although
they are microscopic, what they lack in size
they more than make up in numbers.
• Their collective biological mass (biomass) is at
least 10 times that of all eukaryotes. The
number of bacteria in a single handful of fertile
soil is greater than the number of people who
have ever lived.
• They have even been discovered in rocks 2
miles below Earth's surface.
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BACTERIA
• They perform some of the essential ecological services
such as the recycling of chemicals.
• Only a minority of bacteria cause serious illness in
humans.
• We depend on them for our very survival, and
biotechnology is beginning to harness the metabolic
powers of these organisms for our benefit.
• Improved sanitation, antibiotics, and education have
greatly reduced the incidence of bacterial diseases.
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BACTERIA
• Most bacteria are unicellular, although some species
grow in colonies. Their cells come in three basic shapes:
spheres (cocci), rods (bacilli), and spirals.
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BACTERIA
• Bacteria are first classified by whether or not
they absorb Gram stain, a purple colored dye.
• Those that stain purple are called Gram
positive bacteria, and those that do not absorb
the dye are called Gram negative bacteria.
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Gram Positive
Gram Negative
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Video
• Bacteria Shape (3 mins)
• Bacteria (2 mins)
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BACTERIA
• Gram-positive bacteria are normal inhabitants
on our skin.
• As long as there is no break in the skin, they do
not cause disease.
• However, if the skin is broken, they get into
the wound and cause the typical redness, heat,
and swelling of an infection.
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BACTERIA
• Gram-negative bacteria are normal inhabitants inside
our large intestines.
• We even need them to help digest and absorb our food.
• Large numbers of Gram-negative bacteria are excreted
in the feces.
• If Gram-negative bacteria get on our hands and then
onto our food and into our mouths, they get into the
upper portion of our digestive tract, where they cause
serious disease.
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BACTERIA
• The reason Gram-positives and Gram negatives
react differently to the stain is because of
differences in their cell walls and plasma
membranes.
• Bacteria also have certain cellular features that
differ from eukaryotes.
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PLASMA MEMBRANE
• All cells (prokaryote and eukaryote) have a plasma
membrane; it is a baggie-like structure that holds the
organelles inside of the cell.
• Any substance that can rupture the plasma membrane
will kill the whole organism; therefore this structure is
carefully studied. Alcohol, soaps, and other detergents
easily rupture the plasma membrane of bacteria.
• Gram negative organisms have an inner and an outer
plasma membrane, whereas Gram positive organisms
only have one plasma membrane. The inner from the
outer plasma membrane in a Gram negative bacterium
is separated by a cell wall.
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GRAM NEGATIVE
GRAM POSITIVE
Plasma membrane
Cell Wall
Outer plasma
membrane
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Bacterial Cell Walls
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Figure 3.13a
Bacterial Cell Walls
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Figure 3.13b
BACTERIA
• In Gram negative organisms only, the outer
plasma membrane contains a special structure
called a lipopolysachharide (LPS), which
means it is made of lipids (fats) and many
sugars (polysaccharides).
• The LPS of the plasma membrane in bacteria is
recognized as a foreign element by our
immune system (white blood cells: WBC’s).
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BACTERIA
• This makes it an antigen (something our immune
system sees as foreign and needs to be destroyed).
• The LPS unit is called an “O antigen”. One little piece
of the LPS contains a substance called Toxin A.
• If this toxin builds up in a human or animal, it can
cause septic shock (blood poisoning) and death.
• That is why an infection from a Gram negative
organism is so dangerous. Christopher Reeves
(Superman) died from this.
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GRAM NEGATIVE
O Antigen
Inner plasma membrane
LPS
Cell Wall
Toxin A
(endotoxin)
LPS
Outer plasma
membrane
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CELL WALL
• Prokaryotic cell walls maintain cell shape, provide
physical protection, and prevent the cell from
bursting in a hypotonic environment.
• The cell wall is more complex in prokaryotes
(bacteria) than in eukaryotes (plants). It keeps the
organism from exploding from osmotic shock (too
much water entering into the cell).
• Unlike Archaea, bacterial cell walls contain a
unique substance called peptidoglycan, which is a
combination of peptide (protein) and glycan
(sugar).
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CELL WALL
• Peptidoglycan is only found in bacteria, not in any
other organism. Therefore, this structure is
important to study because we can create
antibiotics that attack peptidoglycan and it will
not harm the cells of the patient.
• Mycoplasma (causes TB or leprosy, depending on
the species) is the only bacteria without a normal
cell wall (its cell wall is 60% waxy). It is neither
Gram-positive nor Gram-negative. It is called
“Acid-fast” because it takes an acidic stain to
color it.
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CELL WALL
• The cell wall of a Gram positive bacterium is
different than a Gram negative bacterium, and
the antibiotics to attack each type of cell wall
are different.
• Gram positive organisms have much more
peptidoglycan than Gram negatives.
• The peptidoglycan is what takes up the purple
Gram stain.
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CAPSULE
• This is a protein sheath that covers the whole
bacterium. Not every bacterium has a capsule; those
that do are more resistant to our immune system.
• Its purpose is to store nutrients and also to protect it
from phagocytosis (ingestion) by our protective white
blood cells which are trying to eat it and kill it.
• Once the bacteria without a capsule is phagocytized
(ingested), the white blood cell releases a sac of
enzymes to dissolve it. Phagocytosis is inhibited by
capsules.
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CAPSULE
• Sometimes, a white blood cell is able to phagocytize a
bacterium with a capsule (for example a tuberculosis
organism in the lungs).
• The bacterium can then live inside the white blood cell
because the capsule also protects it from the
destructive enzymes.
• The WBC now has become an infected host to the
bacteria. The body will try to surround the infected
WBC with calcium deposits to kill the WBC, but
although the WBC dies, the bacteria go on living in this
calcified nodule.
• An x-ray of a TB patient will show these nodules in the
lungs.
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Capsule
TB nodules
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NUCLEOID
• The region of a prokaryotic cell that contains
the cell's DNA.
• It is not enclosed in a membrane; it just stays
together as a mass in the cell.
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FLAGELLUM
• Whip-like tail used for motility; it is difficult to
see under the microscope in live cells, but you
can see the bacteria swimming around.
• The flagella contain a piece of material that
our white blood cells recognize as foreign, so
they attack the bacteria. This piece is called the
H antigen.
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FLAGELLUM
• There is one strain of E. coli called O157.H7
(weird name!).
• The letter “O” followed by a number indicates
the type of LPS antigen and the H7 indicates
the type of flagellar antigen.
• This strain of E. coli is the main pathogen that
you hear about on the news. It produces
intestinal bleeding, especially in babies. It is
found in cattle feces.
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FLAGELLUM
• If there is an outbreak of bleeding diarrhea
that is traced to having eaten spinach at one
restaurant, the Center for Disease Control
(CDC) has to find out where that spinach came
from and pull that product from the grocery
store shelves because it probably did not have
the fertilizer cleaned off it properly.
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FLAGELLUM
• Flagella come in various arrangements:
• Peritricous: Many flagella all around the
perimeter of the cell.
• Lophotrichous: A group of flagella gathered
at one end of the cell.
• Amphitrichous: One flagellum coming out of
each end of the cell.
• Monotrichous: Only one flagellum, comes
out of one end of the cell.
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Names for flagella arrangement
• Monotrichous
• Lophotrichous
• Amphitrichous
• Peritrichous
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Flagella Arrangement
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Figure 4.7
PILI
• Short, thin appendages that help prokaryotes
adhere to surfaces, such as rocks or cells.
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ENDOSPORES
• When essential nutrients are depleted, certain
Gram-positive bacteria form specialized resting
cells called endospores.
• An example is Clostridium, which causes
diseases such as gangrene, tetanus, botulism,
and food poisoning.
• Another example is Bacillus, some species of
which cause anthrax and food poisoning.
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ENDOSPORES
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Figure 4.21a
Video
• Cell Structure and Function (6 mins)
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PROKARYOTES PLAY CRUCIAL ROLES IN
THE BIOSPHERE
• If humans were to disappear from the planet
tomorrow, life on earth would go on for the
prokaryotes.
• However, if prokaryotes disappeared, plants,
animals, and humans would not survive.
• Cyanobacteria (blue-green algae) first gave
Earth its oxygen-containing atmosphere.
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Cyanobacteria
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PROKARYOTES PLAY CRUCIAL ROLES IN
THE BIOSPHERE
• Organic compounds are those which contain carbon.
Carbon atoms always combine with other atoms, such as
oxygen, hydrogen, and nitrogen.
• Therefore, carbon dioxide, carbohydrates, proteins,
enzymes, and lipids are all examples of organic compounds.
• All of the atoms that make up all of the organic molecules in
all living things were at one time part of the inorganic
compounds in the soil, air, and water. Sooner or later, that
is where those atoms will return.
• Ecosystems depend on the continual recycling of chemical
elements between the living and nonliving components of
the environment, and prokaryotes play a major role in this
process.
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PROKARYOTES PLAY CRUCIAL ROLES IN
THE BIOSPHERE
• For example, prokaryotes function as decomposers by
breaking down dead bodies, dead vegetation, and
waste products such as feces.
• During decomposition, the carbon, nitrogen,
hydrogen, and oxygen are released back into the
environment.
• These elements are then absorbed by plants, which
are eaten by herbivores (vegetarian animals), which
are eaten by omnivores (meat eating animals) such as
humans.
• When the plants and animals die, the bacteria
decompose the dead body or vegetation back into the
original elements so that the
cycle can begin again.
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SYMBIOTIC RELATIONSHIPS
• Certain species of prokaryotes have mutually
beneficial associations with eukaryotes.
• An ecological relationship between organisms of
different species that are in direct contact is called
symbiosis (from a Greek word meaning “living
together”).
• If one of the symbiotic organisms is much larger
than the other, the larger is known as the host and
the smaller is known as the symbiont.
• Symbiotic relationships are categorized as either
mutualism, commensalism, or parasitism.
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SYMBIOTIC RELATIONSHIPS
• Mutualism is the relationship where both
symbiotic organisms benefit.
• Commensalism is the relationship where one
organism benefits while neither harming nor
helping the other in any significant way. This
type of relationship is very rare in nature.
• Parasitism is the relationship where one
organism, called a parasite, benefits at the
expense of the host.
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Mutualism
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Commensalism
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Parasitism
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SYMBIOTIC RELATIONSHIPS
• Humans depend on mutualistic prokaryotes.
• For example, human intestines are home to about
1000 species of bacteria; their cells outnumber all
human cells in the body by as much as 10 times.
• Most of these species are mutualists, which digest
food that our own intestines cannot break down.
• Many of them also synthesize carbohydrates,
vitamins, and other nutrients that we need that
we cannot make ourselves, such as vitamin B12
and folate.
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PATHOGENIC PROKARYOTES
• Prokaryotes cause about half of all human
diseases.
• About 3 million people a year die of
tuberculosis, and another 2 million die from
various diarrheal diseases caused by other
bacteria.
• Some bacteria are spread by insects. About
one million people a year die from malaria;
every 30 seconds, one African child dies from
this disease.
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PATHOGENIC PROKARYOTES
• In the United States, the most widespread
disease carried by a pest is Lyme disease,
caused by a bacterium carried by ticks
(especially those found on deer).
This disease starts as a large, ring-shaped
rash around the tick bite, and progresses
to arthritis, heart disease, and nervous
system disorders if left untreated.
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PATHOGENIC PROKARYOTES
• Pathogenic bacteria usually cause disease by producing
poisons which are classified as exotoxins or endotoxins.
• An exotoxin is a protein secreted by the bacteria. Examples
include bacteria that cause cholera and botulism.
• An endotoxin is the toxin found on the LPS portion of the
Gram-negative bacteria’s outer membrane (Toxin A).
• In contrast to exotoxins, endotoxins are released only
when the bacteria die and their cell walls break down.
• An example is Salmonella, which can cause food poisoning
or typhoid fever, depending on the species.
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Salmonella enterica
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Salmonella enterica
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Infections associated with
Enterobacteriaceae
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PATHOGENIC PROKARYOTES
• Since the 19th century, improvements in
sanitation have greatly reduced the threat of
pathogenic bacteria.
• Antibiotics have also saved many lives and
reduced the incidence of disease.
• However, resistance to antibiotics is currently
causing new strains of bacteria to evolve with
immunity to these drugs.
• Other environmental factors can occur that can
cause the genes of bacteria mutate, turning
normally harmless bacteria into fatal pathogens.
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PATHOGENIC PROKARYOTES
• E. coli, for instance, is ordinarily a harmless symbiont in the
human intestines, but pathogenic strains that cause
bloody diarrhea have emerged.
• One of the most dangerous strains, called O157: H 7, was
first discovered in 1982.
• Today it is a global threat; in the United States alone there
are 75,000 cases of this infection per year, often from
contaminated beef or vegetables that have been fertilized
with feces from contaminated cattle.
• This particular strain has a gene that codes for an exotoxin
that enables it to attach to the intestinal wall and extract
nutrients. It is also highly resistant to antibiotics.
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Escherichia coli
Motile species
Non-motile species
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PATHOGENIC PROKARYOTES
• Pathologic bacteria also pose a potential
threat as weapons of bioterrorism.
• In October 2001, endospores of Bacillus
anthrax were found in envelopes mailed to
members of the news media and the US
Senate; 18 people developed anthrax and five
died.
• Other bacteria that could be used as weapons
include those that produce botulism and black
plague.
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Anthrax, Oct 2001
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PROKARYOTES IN RESEARCH AND
TECHNOLOGY
• On a positive note, we reap many benefits
from the metabolic capabilities of bacteria.
• For example, humans use bacteria to convert
milk to cheese and yogurt.
• Modern research includes using bacteria genes
inserted into plants to make them resistant to
insects.
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PROKARYOTES IN RESEARCH AND
TECHNOLOGY
• Prokaryotes are also the principal agents in
bioremediation, the use of organisms to
remove pollutants from soil, air, or water.
• For example, they are used to decompose the
organic matter in sewage, converting it to
material that can be used as fertilizer.
• Other bioremediation applications include
using bacteria to break down radioactive
waste and clean up oil spills.
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Bacteria and Oil Spills
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PROKARYOTES IN RESEARCH AND
TECHNOLOGY
• In the mining industry, prokaryotes help
recover metals from ores.
• Bacteria are used to assist in the extraction of
30 billion kg of copper each year.
• They are also used to extract gold; one factory
in the African nation of Ghana produces one
million kg of gold concentrate a day-- about
half of Ghana’s foreign exchange.
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Gold Mining with Bacteria
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PROKARYOTES IN RESEARCH AND
TECHNOLOGY
• Through genetic engineering, humans can now
modify bacteria to produce vitamins,
antibiotics, insulin, and other hormones and
products.
• Research is underway to produce bacteria that
can produce large amounts of hydrogen to
reduce dependence on fossil fuels.
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Video
• GMO foods by viruses (9 mins)
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VIRUSES
• Viruses were first discovered in 1883 when a German
scientist was studying a disease that stunted the
growth of tobacco plants.
• He found that a diseased leaf could transmit the
disease to a healthy plant, but he could not find any
bacteria present.
• This indicated that there was an organism smaller than
a bacterium that was causing the disease.
• It was not until 1935 that these infectious particles
were identified and called “viruses”.
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Tobacco Virus
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VIRUSES
• These are the smallest of all microbes; hundreds of
viruses can fit inside one bacterium!
• They are acellular (no cells) and they do not have their
own metabolism; they use host cells for metabolism
and replication.
• They do not have a nucleus, and their genetic material
is incomplete: It consists of a core of a fragment of
either DNA or RNA (not both), surrounded by a
protein coat.
• Therefore, viruses can only replicate when they are
living in a host cell; they use the host’s genetic
material.
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Virus
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Video
• Viruses Invading (2 mins)
• Virus Plasmids (5 mins)
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VIRUSES
• A virus that does not contain its own DNA will use
its RNA as a template to transcribe the hosts DNA
into genetic material they can use to replicate.
• Viruses are classified as being DNA viruses or RNA
viruses.
• The RNA viruses don’t have stable genes and they
mutate frequently.
• The most famous example of an RNA virus is AIDS.
•
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VIRUSES
• Viruses are obligate intracellular (must live inside
host cell) parasites (live at the expense of the host,
which it weakens or kills).
• Even when you kill a virus, it can leave behind an active
particle that can cause disease.
• Viruses attack by injecting their DNA or RNA into a cell
and starting a genetic take over of the cell.
• Viral biotechnology includes techniques enabling
scientists to use viruses to obtain genes from one
organism and transfer them into another organism.
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Virus Attack
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VIRUSES ARE HOST
SPECIFIC
• Since a virus does not have metabolic
enzymes, ribosomes, and other equipment for
making proteins, an isolated virus is merely a
packaged set of genes in transit from one host
cell to another.
• Each type of virus can infect only a limited
range of host cells.
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VIRUSES ARE HOST
SPECIFIC
• Viruses identify their host cells by a “lock and
key” fit between proteins on the outside of
the virus and molecules on the surface of cells.
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VIRUSES ARE HOST
SPECIFIC
• A few viruses have a large number of hosts they can
infect.
• West Nile virus, for example, can infect mosquitoes,
birds, horses, and humans.
• Most viruses have a host range so narrow they can
only infect a single species.
• For example, measles and polio only infect humans.
Furthermore, most viruses are so host-specific that
they usually only affect particular tissues.
• Human cold viruses infect only the cells lining the
upper respiratory tract, and the AIDS virus only binds
to certain types of white blood
cells.
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Video
• Flu Attack: How a virus invades your body
• (4 mins)
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VIRAL PATHOGENS
• Diseases caused by viral infections afflict humans,
agricultural crops, and livestock worldwide.
• Examples of viral diseases in humans range from
the deadly HIV to the common cold virus.
• Hepatitis A is a virus that can remain viable (living)
even outside of the host for long periods of time;
it spreads through fecal contamination (food
workers who do not wash their hands after a
bowel movement).
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VIRAL PATHOGENS
• Viruses that seemed to appear suddenly in our society are
referred to as emerging viruses.
• HIV, the AIDS virus appeared in San Francisco in the early 1980’s.
• The deadly Ebola virus appeared in 1976 in Central Africa, causing
hemorrhagic fever.
• The West Nile virus appeared in 1999 in the United States and
causes encephalitis, inflammation of the brain.
• In 2002, the SARS virus appeared in China, causing severe acute
respiratory syndrome.
• Viruses can also infect plants. More than 2000 types of viral
diseases of plants are known, and together they account for the
loss of $15 billion a year due to crop destruction.
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VACCINATION VERSUS
ANTIBIOTICS
• A vaccine is a harmless piece of a pathogenic
microbe (like a piece of flagella from a bacterium)
that will stimulate the body's own immune system
to mount a natural attack against the whole
pathogen.
• Vaccines can prevent some viral infections, but
antibiotics are ineffective for treatment of a viral
infection.
• Antibiotics work by interfering with cell wall
synthesis or metabolism; since viruses don’t have
these things, they are not effective.
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VACCINATION VERSUS
ANTIBIOTICS
• There are medicines that treat but don’t cure viruses,
such as acyclovir for Herpes Simplex 1. In other words,
viruses are very difficult to kill with medicines.
• It is better to get a vaccine to prevent serious viral
diseases.
• The reason there is no cure for the common cold is
that there are millions of different viruses that cause
it.
• If we made a vaccination for one cold virus, you would
still catch another cold from a million different viruses.
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Video
• Bacteria and Viruses (5 mins)
85
HOW MICRO-ORGANISMS CAUSE DISEASE
• BARRIERS TO ENTRY: The skin serves as a
tremendous protection against invasion by
disease-causing organisms.
• There is nothing that can get through unbroken
skin. So why do we have those paper toilet seat
covers? There is nothing you can catch from a
toilet seat as long as you don’t have an open
wound on your buttocks.
• Mucous membranes are also a protective barrier,
but some organisms thrive on the moisture and
can invade those sites.
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TRANSMISSION
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TRANSMISSION
• DIRECT CONTACT: is when you must come in
contact with the body fluids or lesions of an
infected person. An example is catching herpes
from kissing someone with a cold sore.
• AIRBORNE transmission is when the organism is
suspended in the air and carried by moisture away
from the host. An example is catching a cold after
someone with a cold sneezed in the same room
before you walked in.
• It takes 3 days to incubate a cold virus.
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TRANSMISSION
• VEHICLE transmission is when the organism falls
onto an inanimate object and lives there until
picked up by another host.
• An example is a cold virus that you catch from
using a public telephone. You can also get
Salmonella food poisoning from getting raw
chicken juices on a kitchen counter.
• If you don’t clean it up and it gets in your mouth,
you can get really sick. Cooking thoroughly kills
bacteria from meat products.
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TRANSMISSION
• VECTOR transmission is an animal that carries
the disease from one host to another. An
example is getting malaria from a mosquito.
• A PATHOGEN is an organism that causes
disease.
• An OPPORTUNISTIC PATHOGEN only causes
disease when they have an opportunity. We
have many types of bacteria on our body that
don’t cause disease as long as they stay where
they belong.
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TRANSMISSION
91
Mary Mallon (right) in
1931.
First diagnosed as carrier
in 1907. Quarantined and
then released in 1910.
Went back to work as a
cook in 1914 at a NYC
hospital.
Quarantined permanently
to North Brother island in
1915.
www.pbs.org
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TRANSMISSION
• The intestinal bacteria that help us digest our food. If
they get from the colon to an area of broken skin,
they will cause a serious infection.
• That’s why it is so important to wash your hands
after going to the bathroom. If you do wash your
hands, but then touch a contaminated door handle
when you leave the bathroom, everywhere you
touch in the outside world gets contaminated.
• Then everyone who touches what you touch is also
contaminated. Eventually, someone will then touch
their eye or mouth and the
94 organism can get in.
TRANSMISSION
• Another opportunistic type of bacteria is called
staphylococcus, or “staph” for short.
• They normally are found all over the outside of
our skin, but they usually cannot get in.
• Every time you get even a small paper cut, you
should wash it with soap and water and put
TRIPLE ANTIBIOTIC OINTMENT on it and a
Band-Aid (USE PROPER TECHNIQUE) and it will
heal in three days instead of ten days.
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TRANSMISSION
• This ointment kills staph and other common
skin organisms.
• Neosporin ointment kills only one type of
bacteria, but Triple Antibiotic has Neosporin
plus two other types of antibiotics.
• The proper way to put on bandaid is to apply
the ointment to the Band-Aid, and then the
Band-Aid to the wound without touching your
fingers to the ointment or the sterile Band-Aid
pad.
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Cutaneous Disease
• Various skin conditions including scalded skin syndrome,
impetigo, folliculitis, and furuncles
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TRANSMISSION
• One of the major reservoirs that the Staph organisms
hide out is in the nose. That’s why your mother always
told you not to pick you nose!
• Everything you touch after that is spreading Staph
germs. Not washing hands is the major cause of food
poisoning.
• Food poisoning such as Salmonella is frequently
caused from having raw chicken juices left on the
kitchen counter. When the bacteria from the juices
get into other food, you get food poisoning.
• Also, cutting boards in the kitchen should be made of
a material that does not have any nooks and crannies
in it (like plastic), or bacteria
will lodge there.
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TRANSMISSION
• What’s the worst place in the house for germs?
The kitchen sponge.
• Another bad place is a toothbrush. They
should be discarded every three months, and
stored away from a 6’ radius of the toilet
(splash zone). Put them in a cabinet or drawer
but let them dry out.
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TRANSMISSION
• Regarding using hydrogen peroxide (H2O2) to pour on a
wound, keep in mind that it is not a germ killer at all.
• When it comes in contact with blood products, the H2O2
splits its bond and the oxygen comes off and leaves water
behind. The oxygen bubble rises up and can mechanically
cleanse the wound from small debris particles.
• It is good to use after a gravel burn or when there is dirt in
the wound. Soak the wound first so the tissues swell and
force out some of the dirt. Then pour on some hydrogen
peroxide, pat it dry, put on some antibiotic ointment and a
Band-Aid.
• Don’t use iodine or mercurochrome, because it causes scar
tissue.
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TRANSMISSION
• Adults with runny noses leave cold viruses on about 35
percent of objects they touch, such as telephones,
door handles and television controls.
• An hour after someone leaves a virus-infected droplet
on a surface, it can be picked up 60 percent of the
time. And 24 hours later, 33 percent chance of picking
it up.
• You have to get the virus on your fingertip and then
you stick it in your own nose and your own eye.
• Common sites for cold viruses are the light switch, a
pen, faucet handles, the door handle, the TV remote
and the telephone.
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TRANSMISSION
• Is a dog’s mouth cleaner than a human’s?
• Actually, dogs have lots of bacteria in their
mouth, but they are species-specific, so they
can’t live on us.
• It’s much worse to kiss another human than an
animal.
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TRANSMISSION
• Another thing that people tend to do wrong is to
put baking soda in their shoes or socks to absorb
moisture.
• They figure it’s good for the refrigerator; it should
be good for a shoe.
• But what do you think the problem is with this?
Where there is a dark, warm, moist environment,
there will be bacteria.
• Baking soda is a food, so putting it on a fungus
infection or a place where bacteria live is just
feeding them! Use baby powder instead; that’s
not a food product.
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Other Microbiology Concerns
•
•
•
•
•
•
•
Leaving mayonnaise in the sun for four hours
Plastic vs. wood cutting boards
Cutting raw chicken and leaving the juice
Proper way to clean kitchen counters
Use the dishwasher or microwave to sterilize things
Household products that have toxic fumes
Anti-freeze tastes like sugar water, but will kill: keep
away from children
• Household Hazards for children
• Can you catch diseases from a toilet seat?
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SEXUALLY TRANSMITTED DISEASES
(STDS)
1. VIRUSES
A) HIV / AIDS
B) Herpes Infections
C) Hepatitis Infections
2. BACTERIA
A) Chlamydia
B) Gonorrhea
C) Syphilis
3. Other Organisms that cause Sexually Transmitted Diseases
A) Trichomonas
B) Fungi and Yeast
C) Lice
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HIV / AIDS
• HIV / AIDS (acquired immunodeficiency syndrome): Caused by a
virus that infects white blood cells.
• Prevalence
• About 40 million people worldwide have become infected with
HIV, and of these, 12 million have died of AIDS. A new HIV
infection occurs every 15 seconds, the majority in heterosexuals.
Most infected people live in Africa (66%) where it is believed HIV
infections first began, but new infections are now occurring at
the fastest rate in Southeast Asia and India.
• In the United States, HIV infections are more prevalent among
African Americans and Hispanics. Everyone who is sexually active
or who use IV drugs are at risk.
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HIV
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HIV / AIDS
• Symptoms of an HIV Infection
• It attacks white blood cells to destroy a person’s immune system.
During the initial phase, there are no symptoms and the blood test is
negative, yet the person is highly infectious.
• Several months to several years after infection, symptoms begin
with swollen lymph nodes, severe fatigue, fever with night sweats,
and diarrhea are present. If the virus enters the brain there will be
loss of memory, inability to think clearly, loss of judgment, and/or
depression.
• Persons with AIDS die from opportunistic diseases, not from the HIV
infection itself. An opportunistic infection is when a bacteria that
frequently lives on our body without causing disease but will cause
disease if given the opportunity. One opportunity that can present
itself is when the immune system is weakened.
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HIV / AIDS
• Treatment
• There is no cure for AIDS, but they can be
given therapy that usually consists of two
drugs that prevent mutation of the virus to a
resistant strain.
• Unfortunately, if the virus is the resistant
strain, there is no drug therapy.
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HIV / AIDS
• Transmission of HIV
• The largest group of people with AIDS in the United States is
homosexual men, but the largest population of new cases are
intravenous drug users and heterosexuals.
• Women now account for 20% of all newly diagnosed cases of
AIDS. An infected woman can pass HIV to her unborn children or
to a newborn through milk. Transmission at birth can be
prevented if she takes AZT, and delivers by C section.
• HIV is spread in body fluids, such as blood, from one person to
another. (Blood transfusions are now tested for the presence of
HIV, so risk of contracting an infection in this manner is now
considered very unlikely).
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Herpes
• The herpes viruses cause various illnesses. Chicken pox
and mononucleosis (Epstein-Barr) are examples of a
herpes virus.
• However, only the herpes simplex virus is sexually
transmitted. They infect mucosal linings such as the
mouth and vagina.
• There are two types of herpes simplex viruses: type 1
usually causes cold sores and fever blisters, while type
2 more often causes genital herpes.
• However, oral sex with someone with a fever blister
can cause genital herpes and oral sex with someone
with genital herpes can cause fever blisters.
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Herpes
• Cold Sores and Fever Blisters
• Cold sores are usually contracted during childhood
from a smooch from a well-meaning adult with a cold
sore.
• The sores heal and break out again during times of
stress throughout the person’s life.
• The stress can be from emotional stress, illness, menstruation, high fever, colds, or exposure to sunlight.
• These sores are infectious for at least three to four
days until the sores begin to heal.
• Contact with the sores or any contaminated object
can cause the virus to be 113
transmitted.
Herpes cold sores
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Herpes
• Genital Herpes
• Genital herpes is what causes genital warts.
• All warts are caused from a virus. A regular wart on
the hands or plantar wart on the feet is harmless, but
they can spread, get bigger, and cause discomfort.
• Genital herpes is a sexually transmitted wart.
• Over one million persons a year become infected, but
not everyone goes in for treatment.
• It is caused from having intercourse with someone
who has genital herpes, or from having oral sex with
someone with a cold sore.
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Genital Herpes
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Herpes
•
•
•
•
•
Transmission and Symptoms
In some people there are no symptoms, so many people don’t know they have
them.
They start as a tingling or itching sensation before blisters appear on the genitals.
Once the blisters rupture, they leave painful ulcers that may take as long as three
weeks or as little as five days to heal. The blisters may be accompanied by fever,
some burning on urination, swollen lymph nodes in the groin, and in women, a copious vaginal discharge. As with cold sores, the blisters come back from the same
stress situations.
A newborn can become infected by passage through the birth canal so they have
to be delivered by C-section.
Genital warts are associated with cancer of the genitals. Teenagers with multiple
sex partners are very susceptible to genital warts, and more cases of cancer of the
cervix are being seen among this age group.
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Herpes
• Treatment
• There is no cure for genital herpes.
• There are some pills or ointments that disrupt the reproduction
of the virus and so relieve the initial symptoms at the first sign of
outbreak, but it will always come back later.
• They can be temporarily removed by surgery, freezing, acid, or
laser.
• However, as with all warts, there is a high likelihood of
reoccurrence.
• Even after treatment, the virus can be transmitted because the
wart may look gone, but it lingers in the subdermal tissues.
• Therefore, abstinence or use of a condom is necessary.
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119
Hepatitis
• There are several types of hepatitis. There is no cure,
but there is a vaccine.
• Hepatitis A
• This is a virus you get when you or a food worker
doesn’t wash the hands after going to the bathroom,
and then you eat. It can also be sexually transmitted
through oral/anal contact.
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Hepatitis
Hepatitis B
• This is the form that is primarily spread by sexual contact or
sharing needles by drug users.
• Only about 50% of infected persons have flu-like symptoms,
including fatigue, fever, headache, nausea, vomiting, muscle
aches, and dull pain in the upper right of the abdomen.
Jaundice, a yellowish cast to the skin, can also be present. Some
persons have an acute infection that lasts only three to four
weeks. Others have a chronic form of the disease that leads to
liver failure and a need for a liver transplant.
•
•
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Hepatitis
•
Since there is no treatment for an HBV infection, prevention is
imperative by a vaccine, which is safe and does not have any
major side effects. This vaccine is now on the list of recommended immunizations for children.
•
• Hepatitis C
• This is the form you get from infected blood. It is very serious
and can lead to chronic hepatitis, liver cancer, and death.
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Hepatitis A
123
Hepatitis B
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Hepatitis C
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BACTERIA
• Bacterial diseases are controlled by preventing transmission and by antibiotics. Abstinence or
monogamous relations (always the same partner) with
someone who is free of an STD will prevent
transmission.
• Otherwise, the use of a condom and avoidance of
oral/genital contact is recommended.
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Chlamydia
• Chlamydia is the leading STD in the United States.
There are about 6 million new cases per year.
• Five times more women than men go in for treatment
for this because women have more symptoms and
men who are infected don’t know it.
• Chlamydia is easily treated with antibiotics.
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Chlamydia
• Symptoms
• At first there may be no symptoms, but after 1-3 weeks
there may be a mild burning sensation on urination
and a mucous discharge in vagina. Unfortunately a
physician mistakenly may diagnose it as a urinary tract
infection and prescribe the wrong type of antibiotic;
until they realize the medicine is not working, the
person is still contagious.
• If the infection spreads to the ovaries, she’ll get pelvic
inflammatory disease (PID) results. This is a very
painful condition with no treatment and no cure. It
also causes sterility. The woman has to live with this
severe pain for the rest of128her life.
Chlamydia
• If a newborn comes through the birth canal of a
women with Chlamydia, its eyes become infected and
results in blindness.
• This is the leading cause of blindness in third-world
countries. That is sad, because all it requires are some
eye drops in the infant right after birth, and it will
prevent this. This STD is easily cured with tetracycline.
• The leading cause of blindness in newborns is from
Chlamydia infections in their eyes after passing
through an infected birth canal.
• Adults can get it in their eyes, too, if they touch an
infected area and rub their eyes. Eye infections cause
blindness.
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Chlamydia
130
Gonorrhea
• Gonorrhea was at an all-time high in 1978, but
it’s going down now.
• Women using birth-control pills or an IUD have
a greater risk because they cause the genital
tract to be more receptive to pathogens.
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Gonorrhea
• Symptoms
• Unlike Chlamydia, gonorrhea symptoms are more
obvious in men than in women. Men have pain on
urination and a milky urethral discharge three to five
days after contact.
• In women, there are usually no symptoms until after it
spreads to the ovaries, again causing PID (a million
women a year get this). Since PID scars up the area
around the ovaries, pregnancy can result in an ectopic
pregnancy (implantation outside of the womb).
• Oral/genital contact can cause infection of the mouth,
throat, and the tonsils. Gonorrhea can spread to
internal parts of the body, causing heart damage or
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arthritis.
Gonorrhea
133
Gonorrhea
• Transmission and Treatment
• The chances of getting a gonorrheal infection
are good. Women have 50—60% risk, while
men have a 20% risk of contracting the disease
after even a single exposure to an infected
partner.
• Painful urination usually indicates gonorrhea.
• Gonorrhea is easily cured using antibiotics.
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Syphilis
• Syphilis is caused by a bacterium that has a tail and can move, so
it is particularly nasty.
• Syphilis has three stages.
• Primary stage: an ulcerated sore with hard edges appears at the
site of infection. The ulcer heals itself, but it is just gearing up for
the next stage.
• Secondary stage: the bacteria spread throughout the body and a
skin rash forms all over, although it is not itchy. Again, it heals
itself, but the worst is on its way.
• Tertiary stage: lasts until the patient dies. It weakens the arteries,
causing aneurysms, and is known for attacking the brain.
Symptoms include mental impairment, blindness, and insanity.
Henry VIII died from syphilis.
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Primary Syphilis
• Symptoms include:
– Chancre that should
heal by itself in 3-6
weeks
• painless
–
–
–
–
genitals
Mouth
Skin
rectum
• Enlarged lymph nodes
near the chancre
136
Secondary Syphilis
• Spotted rash all over
• Fever
• general ill feeling
• loss of appetite
• muscle aches
• joint pain
• enlarged lymph nodes
• hair loss may occur.
137
Tertiary Syphilis
• Cardiovascular syphilis
causes aneurysms or
valve disease
• Central nervous system
disorders
(neurosyphilis)
• Infiltrative tumors of
skin, bones, or liver
(gumma)
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Syphilis
• Diagnosis and Treatment
• Diagnosis of syphilis can be made by blood tests and
microscopic examination of fluids from lesions.
• It is easily cured by penicillin, but once it enters the
last stage, there is no cure and is fatal.
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Other Organisms that cause Sexually
Transmitted Diseases
• A) Trichomonas is a single cell parasite which is transmitted sexually and
causes severe itchiness a woman’s vagina. Men are usually asymptomatic
(no symptoms).
• B) Fungi and Yeast are pathogens from the plant kingdom. When a
woman takes an antibiotic while using birth-control pills, it disrupts the
normal balance of bacteria, and allow normal yeast there to cause an
infection.
• C) Lice are insects that can infect the hair of humans. Head lice are well
known for infecting the hair of schoolchildren; lice on the pubic hair are
called “crabs”, and are sexually transmitted and also can be contracted
by contact with an infected person’s clothing or bedding. They suck
blood from their host and cause severe itching, particularly at night. The
pubic hair, underarm hair, and even the eyebrows can be infected, and it
can be self-diagnosed by examination of the hair. Protozoa, yeast,
worms, and lice are all easily treated with antibiotics and disinfection of
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sheets and clothing.
Trichomonas
141
Fungus Infection
142
Lice
143
Sexually Transmitted Diseases
• Prevention is still the best way to manage STDs.
• The use of a condom along with a spermicide that
contains nonoxynol-9
• The avoidance of oral/genital contact
• Have a monogamous relationship
• Don’t have sex with someone who has a STDs
• Don’t have sex with an intravenous drug user.
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