Download Antibacterials

Antibacterials
Stephanie Amatuzzo
Katelynn Granger
Kelly Beasley
Marley Roberts
 D.6.1 Outline the historical development of
penicillins.
 D.6.2 Explain how penicillins work and
discuss the effects of modifying the sidechain.
 D.6.3 Discuss and explain the importance of
patient compliance and the effect of penicillin
overprescription.
 D.8.3 Explain the importance of the betalactam ring action of penicillin.
D.6.1 Outline the historical development
of penicillins; The background
 1940: Penicillin is founded
 opened era of antibiotics
 Antibiotics: compounds produced by bacteria and fungi
which are capable of killing, or inhibiting, competing
microbial species
 Development of penicillin is seen as greatest advancement in
therapeutics
 Combined efforts of United States and United Kingdom
 Actually discovered in UK
 Due to WWII USA mass produced the product
Before Penicillin…
 No effective treatment for infections such as pneumonia,
gonorrhea, or rheumatic fever
 Ancient Egyptians had the practice of applying a poultice of
moldy bread to infected wounds.
The Discovery
 Alexander Fleming, 1928
 sort through petri dishes containing colonies of Staphylococcus,
bacteria that cause boils, sore throats, and abscesses.
 He noticed something unusual on one dish. It was dotted with
colonies, save for one area where a blob of mold was growing.
 The zone immediately around the mold - later identified as a rare
strain of Penicillium notatum - was clear, as if the mold had
secreted something that inhibited bacterial growth.
 isolated pure penicillin from the mold juice
Lab experiment to life saver
 Their work on the purification and chemistry of penicillin
began in 1939
 wartime conditions were beginning to make research especially
difficult
 February 12, 1941: First taken by a human
 Healed a man within days having
huge abscesses affecting his eyes,
face, and lungs
The USA saves the day
 Britain not able to mass produces because of war
 US began mass producing penicillin
 Increased production
 Substituted lactose for sucrose
 Added corn-steep liquor to fermentation medium
 Exposed strand to UV light
D.6.2 Explain how penicillins work and discuss the
effects of modifying the side- chain.
 How penicillin destroy bacteria:
Prevents cell wall formation so cell shape can't be maintained
2. Water enters the cells
3. The cells burst and the bacteria die.
1.
There are two types of bacteria…
 Gram positive and gram negative.
 Gram positive bacteria have a simple cell wall.
 Gram negative bacteria have complex many layered
cell walls.
 Some antibiotics are ineffective because it is
difficult to penetrate the outer layer of gram
negative bacteria.
Effects of Modifying the Side Chain
The structure of penicillin contains
 An R group (side chain)
 A carboxylic acid group, and
 A beta- lactam ring
 Different types of penicillin vary
in their R group (side chain).
R group
Modifying the R group changes
the bacteria destroying ability of
the penicillin, therefore the
structure of penicillin affects its
ability to work in different
environments.
 Different R groups side
chains changes its
activity.
Beta- lactam
ring
Carboxylic acid
group
 The First Penicillin was called
Penicillin G. However it was
deactivated by stomach acid
so, the benzene side chain
was modified to form the
modern form of Penicillin V
(regular broad spectrum
antibiotic prescribed today),
which is acid resistant, more
soluble in water and is
resistant to penicillinase.
Penicillinase is an enzyme
produced by bacteria that
deactivates penicillin
preventing it from destroying
bacteria.
 Penicillin G
 Penicillin V
D.6.3 Discuss and explain the importance of patient
compliance and the effect of penicillin over-prescription.
:30
Broad vs. Narrow Spectrum Antibiotics
 Narrow spectrum antibiotics
 effective against certain types/strains bacteria leaving other
unharmed.
 The specific bacteria is identified with a blood or urine test so
the specific antibiotic can be identified and prescribed.
 Broad spectrum antibiotics
 effective against a wide range of types and strains of bacteria,
including helpful/beneficial ones (major disadvantage).
 Blood/urine test not required.
 Can be brought over the counter.
 The destroyed bacteria may also be replaced with harmful
strains of the same bacteria.
Patient Compliance
 Symptoms of a bacterial infection often disappear after a few
days, so people may think that they are free from the
infection
 In reality, the symptoms are gone, but the bacteria are still
present in the body
 Stopping antibiotics before the medication runs out increases
the number of antibiotic-resistant bacteria and decreases the
effectiveness of the antibiotics
 This can lead to more severe illness or even hospitalization,
depending on the type and strength of the bacteria.
Disadvantages of Over-prescription of
Penicillins
 About 10% of the population experiences allergic reactions to
penicillins (like fever, rash, shock, and/ or death)
Overprescription can also have these results.
 Helpful bacteria in the alimentary canal can be wiped out by
antibiotics and can be replaced by more harmful strains of the
same bacteria.
 When antibiotics are used extensively, the few bacteria that
survive pass on their resistance when they reproduce. This
results in strains of the bacteria that are resistant to one or more
antibiotics, such as some strains of tuberculosis, typhoid, and
gonorrhea.
 Mutations in a bacterium can also cause antibiotic resistance,
sometimes coupled with increased reproductive abilities.
Furthermore..
 More research is needed to develop new antibiotics that
will be effective on bacteria that are resistant to existing
antibiotics
 Antibiotics should only be used when no other treatment
can reduce a patient’s suffering or save their life.
 This does not always work, since antibiotics are often misused
and abused in today’s society
Antibiotics in Animal Feedstock
 Antibiotics are used in animal feedstock as supplements to
increase the growth of the animals and control the spread of
disease
 They are used to eliminate pathogens that may be present in the
feedstock and increase productivity
 This continuous, low-dose exposure to antibiotics stimulates the
evolution and spread of drug-resistant bacteria
 The same antibiotics that are found in animal feedstock are used
to treat bacterial infections in humans
 Therefore, these strains of bacteria can also affect humans.
D.8.3 Explain the importance of the
beta- lactam ring action of penicillin.
 The beta- lactam ring is a heroatomic
ring structure consisting of one
nitrogen and three carbons
 Square planar structure, bond angles
of 90˚
 The carbon atoms and the nitrogen would
prefer tetrahedral angles of about 109˚ and
the carbon double bonded to the oxygen
would prefer an angle of 120˚.
 The angles of 90˚ therefore place the
ring under chemical stress, which
increases its chemical reactivity,
opening the ring.
Beta- lactam
ring
Effects of the Open Ring
 This open structure is able
to covalently bond to the
enzyme transpepidase
which is responsible for the
synthesis of the bacterial
cell walls, thus blocking the
action of the enzyme.
 The reaction of the
penicillin with the enzyme
is NOT reversible and thus
it inhibits the synthesis and
growth of bacteria in the
cell wall. More specifically,
it prevents the cross linking
of the peptides; the
bacteria burst without the
linkage between the
bacterial cell walls.