Antibiotics - Prior Lake-Savage Area Schools

Bacteria


and

Humans

Bacteria and Disease

Pathology
= study
of disease


Pathogens
= bacteria
that cause
disease

Bacteria grow best with
warmth,
darkness, and moisture.

Toxins


are
poisons

produced by bacteria

Exotoxins
= toxins that are made of protein
-
excreted by bacteria

Produced by G+ bacteria

*
Steadily secreted into the environment

Example
-

tetanus

can
cause tissue death
-
gas
gangrene


Endotoxins

Made of lipids and carbohydrates found on
the
outer membrane of G
-

bacteria

Example
-
E. coli

*
Only released when bacteria is dead

Cause fever, body aches and weakness
-
damage vessels of circulatory system

Body tissue destruction

Adhere to cells, secrete digestive enzymes
and allow tissue invasion and destruction


Example
-
Streptococci

produce blood
-
clot
dissolving enzymes that spread to other
tissues

Impetigo

infection

Bacterial
Diseases

Which of the above are transmitted by
vectors
?

Antibiotics

**Combat
bacteria by
interfering with
various cellular
functions

Many are derived
from chemicals
that bacteria and
fungi produce
(
penicillin
)

Types of Antibiotics

Penicillin, Ampicillin
= interferes with cell
-
wall
synthesis

Tetracycline
= interferes with bacterial protein
synthesis

Sulfa
drugs
= inhibit cell metabolism

Broad
-
spectrum
antibiotics
= affect many
types of bacteria

Testing Bacteria for Antibiotic Sensitivity

Bacteria are grown in an
agar nutrient gel

covering the bottom of Petri dishes.

A paper disc with an antibiotic is placed on the agar gel.


The
clear area
around the disc shows the area that bacteria have been killed.

The larger the clear area, the more effective the antibiotic
.

Zone of dead

Bacterial

inhibition

Antibiotic Resistance

“
Natural Selection

in Action”

1. Population of bacteria is exposed to
antibiotic.

2. Most susceptible bacteria die.

3. A few mutant (naturally immune) bacteria
survive.

4. Mutant bacteria reproduce and recombine.

5. New population is resistant

Mechanisms of antibiotic resistance

Some bacteria block passage of antibiotic
into cell

Some secrete enzymes that destroy or alter
antibiotic (penicillin resistant bacteria)


Major Reason for Resistance

Overuse of antibiotics

result in many
diseases being more difficult to treat
.

Because there are slight variations in
each species of bacteria, some are
effectively killed while others remain to
reproduce.

Look up “
Flesh eating bacteria
” to see effects
of bacterial resistance to antibiotics.


Useful bacteria


Break down sewage

Recycle dead organisms (composting)

Carbon
fixation

Nitrogen fixation

Oxygen release (photosynthesis}

Food processing

-

milk products
-
buttermilk, sour cream, yogurt

Cheeses
-
ricotta, cottage cheese

Sauerkraut,
pickles,
kimchi

Fiber retting (separating plant fibers for rope)

Produce chemicals and fuels

Insecticides, clean up oil spills

Genetic research

Genetic Engineering

Assignments

Study Guide 18
-
6