Antibacterial Drugs

Question 1

What is the difference between Narrow Spectrum and Broad Spectrum Antimicrobial?

Answer 1

Narrow Spectrum: Effective against a limited number of bacterial genera

Broad Spectrum: Effective against a large number of bacteria genera

Question 2

Give two classes of antibiotics which target cell wall synthesis

Answer 2

• Beta lactams

- Glycopeptides

Question 3

Describe the mechanism of action for Beta lactam antibiotics

Answer 3

Beta lactams are analogues to D-Ala-D-Ala, the terminal residues of NAM-NAG subunits, which are required for the final transpeptidation step performed by PBPs. Beta-lactams bind to PBPs which otherwise complete this step, hence wall synthesis is inhibited

Question 4

State two subclasses of Beta-lactam antibiotics

Answer 4

Pencillins

Cephalosporins

Question 5

Describe the mechanism of Glycopeptides

Answer 5

They bind to cell wall sub-units and prevent incorporation of a new unit

Question 6

Give an example of a Glycopeptide

Answer 6

Vancomycin

Question 7

Glycopeptides are only selective against one class of bacteria - which one?

Answer 7

Gram+

Question 8

What are the differences in Ribosomes between Eukaryotes and Prokaryotes?

Answer 8

Eukaroyes - 80s (60s + 40s)

Bacteria - 70s (50s + 30s)

Question 9

Give 2 examples of 30s Inhibitor Antibiotics

Answer 9

Aminoglycosides

Tetracyclines

Question 10

Give 3 examples of 50s Inhibitor Antibiotics

Answer 10

Chloramphenicol
Erythromycin
Clindamycin

Question 11

What are the three ways we can target Bacterial Protein Synthesis

Answer 11

• Target ribosomes
• Target tRNA inhibitor
• Target EF-G elongation factor

Question 12

Give 1 example of EF-G elongation factor inhibitors

Answer 12

Fusidic acid

Question 13

Of the 30s ribosome subunit inhibitors, which are bactericidal and which are bacteriostatic?

Answer 13

Aminoglycosides - Bactericidal

Tetracyclines - Bacteriostatic

Question 14

Give 1 example of an Aminoglycoside drug

Answer 14

Gentamycin

Question 15

Give two classes of drugs which inhibit bacterial Nucleic acid synthesis. What do they inhibit?

Answer 15

1. Quinolones - DNA inhibition

2. Rifamycins - mRNA inhibition

Question 16

What is the mechanism of action for Rifampicin?

Answer 16

Rifampicin is a type of Rifamycin, hence it blocks RNA nucleic acid synthesis. Blocks DNA-dependent RNA polymerase

Question 17

Give 1 example of a Quinolone drug

Answer 17

Ciprofloxacin

Question 18

Give two classes of drugs which inhibit bacterial metabolic pathways

Answer 18

Sulfonamides

Trimethoprim

Question 19

What 1 class of drugs affect bacterial cytoplasmic membranes?

Answer 19

Polymyxins

Question 20

Give one example of Polymyxins

Answer 20

Colistin

Question 21

How do we classify antibiotic resistance?

What is it based on?

Answer 21

Three stages:

1. Sensitive
2. Intermediate
3. Resistant

Based on Minimum Inhibitory Concentration

Question 22

What is MIC with respect to antibacterial agents?

Answer 22

Minimum concentration of the antibacterial agent required for bacterial growth to be inhibited

Question 23

Give 4 examples of ways bacteria have developed resistance to antibiotics

Answer 23

Beta-lactamase
Acquisition of mutations
Plasmids
Increase of efflux pumps

Question 24

What MDR-TB?

Answer 24

Multidrug resistant TB

TB which is resistance to atleast 2 first-line TB drugs (Isoniazid + Rifampicin)

Question 25

What is XDR-TB?

Answer 25

Extensive drug resistant TB

TB which is resistant to 3 or more of the 6 classes of 2nd line drugs

Question 26

How can we reduce ABX resistance?

Answer 26

• Optimize therapy for individual patients
• Prevent overuse, misuse and abuse
• Minimize development of resistance at patient and community levels
• Development of rapid diagnostics for infection and resistance
• Further antibiotic development