Antimicrobial Chemotherapy, Agents And mechanisms

Question 0

How are antimicrobials classified?

Answer 0

Chemical structure (e.g. Beta lactam ring)
By target site
According to whether they are bactericidal (kill) or bacteriostatic(inhibit growth)

Question 1

When are antimicrobials agents therapeutically useful?

Answer 1

When the target is not present in man AND

If the target in microorganism has higher affinity for the drug than man.

Question 2

How do we test antibiotics?

Answer 2

Disc diffusion on agar

In liquid MBC/MIC testing

Question 3

What do MIC and MBC stand for?

Answer 3

Minimal Inhibitory Concentration

Minimal Bacteriocidal Concentration

Question 4

What are the main targets for antimicrobials?

Answer 4

Cell wall - peptidoglycan
Protein synthesis - ribosomes or enzymes
Metabolic pathways
DNA
Membranes
Enzymes

Question 5

What agents target the cell wall? (Peptidoglycan is a unique structure- it needs to be cross linked)

Answer 5

Beta-lactams e.g. Penicillins and cephalosporins
Glycopeptidases e.g. Vancomycin, teicoplanin
Cycloserine - inhibits alanine racemase and D-alanine ligase

Question 6

Penicillins and Cephalosporins are what class of antimicrobial?

Answer 6

Beta lactams

Question 7

Vancomycin and Teicoplanin are what type of antimicrobial?

Answer 7

Glycopeptides

Question 8

How does cycloserine work?

Answer 8

Inhibits alanine racemase and D-alanine lipase

Question 9

Are beta lactams bactericidal or bacteriostatic?

Answer 9

Bactericidal.

They contain a beta lactam ring and inhibit normal cell wall formation

Question 10

What type of antimicrobial agent contains an aminocyclitol ring linked to a sugar? E.g. Gentamicin

Answer 10

Aminoglycosides.

Question 11

What type of microorganism are Aminoglycosides effective against?

Answer 11

Aerobes and facultative anaerobes (not anaerobes) as they need oxygen to be taken up by bacteria.

Question 12

Which type of antimicrobial agent is not taken up by the gut so needs to be given IV or IM?

Answer 12

Aminoglycosides

Question 13

Are tetracyclines bactericidal or bacteriostatic?

Answer 13

Bacteriostatic. They are all broad spectrum, they penetrate mammalian cells to reach intra cellular organisms, they are incroporated into developing bone and teeth.

Question 14

Why is use of tetracyclines restricted?

Answer 14

Die to widespread resistance

Question 15

What are macrolides? And give one example.

Answer 15

A family of large cyclic molecules all contain a macrcyclic lactone ring.
Erythromycin is most commonly used.

Question 16

What is commonly used as a role ament for penicillin allergic patients?

Answer 16

Erythromycin. It penetrates mammalian cells to reach intra cellular organisms