Exercise 8 Antibiotics

Front 1

Paul Ehrlich

Back 1

1910, initially use Salvarsan to treat patients with Trepenema pallidum;
Selective toxiticity;
Father of chemotherapy.

Front 2

Salvarsan

Back 2

used by Paul Ehrlich in 1910 to treat Trepenema pallidum, the causative agent of syphilis.

Front 3

Treponema pallidum

Back 3

the causative agent of syphillis
gram-
spirochaete

Front 4

Alexander Fleming

Back 4

Penicillin in 1940.

Front 5

Antibiotic

Back 5

a chemical produced by one microorganism that inhibits or kills another microorganism.

Front 6

Antibiotic working mechanism

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1. Compete for nutrients and space;
2. targeting some essential metabolic process and disrupting it.
3. Selective toxicity

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Selective toxicity

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1. attributed to Paul Ehrlich, the father of chemotherapy.
2. The effectiveness of an antibiotic should be relatively non-toxic to the host while selectively targeting a unique metabolic function (mode of action) of the microbe of interest.

Front 8

Mode of action

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a unique metabolic function of microbe of interest

Front 9

Antibiotic category

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semi-synthetic
synthetic

Front 10

Synthetic antibiotics

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completely created in the lab.

Front 11

Semi-synthetic antibiotic

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altering the naturally made antibiotics in the lab to increase its effectiveness

Front 12

Sulfa drugs

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sulfa drugs make up an interesting group of synthetic chemicals.
azo dye;
Prontosil
effective in treating streptococcal infection in vivo (in body)
ineffective in vitro (in the test tube)

Front 13

In vivo

Back 13

growth of microbes in the body (live plants and animals)

Front 14

In vitro

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Growth of microbes in the laboratory (in test tubes)

Front 15

Prontosil

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sulfa drug;
enzyme in blood activates sulfanilamide, which is an antimetabolite;
If activated, can kill streptococci in vivo and in vitro.

Front 16

antimetabolites

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chemicals that are very similar in size and shape to the substrate of the chemical reaction and therefore can bind to active site and inhibit the metabolic reaction.

Front 17

Antimetabolite

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a substance that inhibits the utilization of a metabolite necessary for growth.
chemicals that are very similar in size and shape to the substrate of the chemical reaction and therefore can bind to the active site and inhibit metabolic reaction.

Front 18

Sulfa drug and folic acid synthesis

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sulfa drug act as a competitive inhibitor;
Sulfa drug block the binding of paraaminobenzoic acid (PABA), which is essential in folic acid synthesis;

Front 19

Blocking folic acid synthesis

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selectively toxic;
harmful to bacteria but not to the host.

Front 20

competitive inhibition

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The inhibition of enzyme activity by competition between the inhibitor and the substrate for the active site of the enzyme.

Front 21

Antiseptics

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a chemical that inhibits or kills vegetative cells. It must be relatively non-toxic so that it is safe to use on living tissue such as skin and mucous membrane.

Front 22

Disinfectant

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a chemical that kills vegetative cells on inanimate objects. It is generally too toxic to be used on living tissue.

Front 23

Antiseptics or Disinfectant

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toxicity;
70% isopropanol can be used as both;
Lysol can only be used as disinfectants.

Front 24

Kirby-Bauer disc diffusion assay

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1. used to determine the potency of antibiotics and antimicrobial chemicals;
2. used to determine the effectiveness of several antibiotics and antimicrobial.

Front 25

Principle of Kirby- Bauer disc diffusion assay

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1. to create bacterial lawn;
2. use antibiotic discs on different areas of the bacterial lawn;
3. observe the diameter of the zone of inhibition.

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Antimicrobial Susceptibility

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R: resistant;
S: susceptible;
I: intermediate.

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Zone of Inhibition

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the size of zone of inhibition will determine the chemical's effectiveness.
The smaller the zone of inhibition, the less effective that chemical was at inhibiting the growth of the organism;
The larger the zone of inhibition, the more effective the chemical at inhibiting growth.

Front 28

Factors to be considered to determine the effectiveness of the antibiotics

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1. size of chemical
2. viscosity of liquid
3. the liquid's ability to penetrate porous surfaces like agar;
4. only determine the effectiveness of the antimicrobial if it forms a zone of inhibition for at least one of the test organism.

Front 29

Materials used for Antibiotic susceptibility

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1. Escherichia coli
2. Pseudomonas aeroginosa
3. Staphylococcus aureus