Antibiotics

Question 1

What are the four shapes of bacteria?

Answer 1

Bacillus, coccus, spiral, other.

Question 2

What are the two types of bacterial cell walls?

Answer 2

Gram-negative and gram-positive.

Question 3

What are gram-positive walls?

Answer 3

Consist of thick layers of peptidoglycan.

Question 4

What are gram-negative walls?

Answer 4

Cell walls that do not contain much peptidoglycan and instead contain two separate membrane layers.

Question 5

What is the structure of peptidoglycan?

Answer 5

Glycan strands made of alternating N-acetylglucosamine and N-acetylmuramic acid cross-linked by peptides.

Question 6

How are individual glycan strands polymerized into a chain?

Answer 6

By glycosyltransferase (GT)

Question 7

How are the glycan strands CROSS-LINKED?

Answer 7

Transpeptidase (TP)

Question 8

What are the four types of diseases caused by pathogenic bacteria?

Answer 8

Food borne illnesses
Sexually transmitted diseases.
Skin infections
Highly infectious diseases

Question 9

What four characteristics are antibiotic efficacies described by?

Answer 9

1. Spectrum of acitivity.
2. Bacterial sensitivity.
3. Therapeutix index.
4. Ability to penetrate.

Question 10

What are bacteriocidal antibiotics?

Answer 10

Leads to a permanent loss of replicative ability.

Question 11

What are bacteriostatic antibiotics?

Answer 11

Leads to a temporary loss of growth and replication that returns following removal of antibiotics.

Question 12

What are the four classes of antibiotics?

Answer 12

Cell wall inhibitors, folic acid, DNA synthesis inhibitors, protein synthesis inhibitors.

Question 13

What is the mechanism of cell wall inhibitors?

Answer 13

Inhibit enzyme DD-transpeptidase responsible for crosslinking components of the cell wall.

Question 14

What is DD transpeptidase also known as?

Answer 14

Penicillin binding protein.

Question 15

What are cell wall inhibitors most effective against?

Answer 15

Gram-positive bacteria.

Question 16

What are beta-lactamases?

Answer 16

Bacterial enzymes made by staphylococci that confer resistance against cell wall inhibitors.

Question 17

What are beta-lactamase inhibitors?

Answer 17

Used in combination with cell wall inhibitors to prevent bacterial resistance.

Question 18

What is vancomycin?

Answer 18

Inhibits peptidoglycan cross-linking, produced in other bacteria.

Question 19

What is the mechanism of folic acid inhibitors?

Answer 19

Drugs that resemble PABA (folic acid precursor) interfere with folic acid synthesis, inability to synthesize purines.

Question 20

What are three examples of protein synthesis inhibitors?

Answer 20

Chloramphenicol, tetracyclines, macrolides.

Question 21

What ribosomal complex does bacteria use to synthesize protein?

Answer 21

70s complex composed of 50s and 30s subunits.

Question 22

What is the mechanism of chloramphenicol and macrolides?

Answer 22

Bind to 50s subunit to block transpeptidation.

Question 23

What is the mechanism of tetracyclines?

Answer 23

Bind to 30s subunit to prevent binding of incoming tRNA.

Question 24

How does aminoglycoside inhibit protein synthesis?

Answer 24

Bind to the 30s subunit to block initiation, cause misreading, inhibit translocation.

Question 25

What are the 4 mechanisms of bacterial resistance?

Answer 25

1. Drug inactivation or modification.
2. Alteration of binding site.
3. Alteration of metabolic pathways.
4. Reduced drug accumulation via pump.