Antibacterials

Question 1

What do bactericidal drugs do?

Answer 1

Kill bacteria by disrupting cell wall synthesis, do not rely on host defenses.

Question 2

What do bacteriostatic drugs do?

Answer 2

Stop the growth of bacteria by interfering with DNA synthesis, protein production or metabolism. The host defense then removes the static bacteria.

Question 3

Give to inhibitors of folic acid synthesis

Answer 3

Sulphonamide

Trimethoprim

Question 4

What does sulphonamide resemble?

Answer 4

p-aminobenzoic acid (essential precursr of folic acid)

Question 5

What does trimethoprim resemble?

Answer 5

pteridine ring

Question 6

Are folic acid inhibitors bacteriostatic or bactericidal?

Answer 6

Bacteriostatic.

Question 7

What is the drug of sulphonamide combined with trimethoprim called?

Answer 7

Co-trimaxzole

Question 8

What is trimethoprim chemically related to?

Answer 8

Anti-malarial drug pyrimethamine

Question 9

What can trimethoprim be used for?

Answer 9

Many bacterial infections including UTIs and respiratory infections.

Question 10

Which type of bacteria are harder for antibiotics to penetrate?

Answer 10

Gram-negative, because it has a more complex cell wall and cell membrane.

Question 11

What does B-lactamase do?

Answer 11

Inactivated B-lactam which kills bacteria

Question 12

What does clavulanic acid do?

Answer 12

Inhibits many B-lactamases so the B-lactam can kill the bacteria

Question 13

What do B-lactams do?

Answer 13

Break oligopeptide linkages between chains of GlcNAc and MurNAc

Question 14

Give 4 examples of semi-synthetic penicillins

Answer 14

1. Amoxicillin
2. Ampicillin
3. Flucloxacilin
4. Carbenicillin

Question 15

What are penicillins?

Answer 15

Effective widely used antibiotics with a narrow to a broad spectrum of uses. Destroyed by bacterial amidases and B-lactamases. Interfere with cell wall peptidoglycan synthesis.

Question 16

Give 3 uses of penicillins

Answer 16

1. Bacterial meningitis
2. Pneumonia
3. Bone and joint infections

Question 17

What are cephalosporins?

Answer 17

Naturally occuring with the same mechanism of action to penicillins. They are the 2nd choice for many infections. Lipid soluble. Vary in susceptibility to B-lactamases.

Question 18

Give to examples of B-lactamase resistant B-lactam antibiotics.

Answer 18

Carbapenem.

Monolactam

Question 19

GIve 3 antibiotics which inhibit bacterial wall synthesis but don’t target B-lactamase.

Answer 19

1. Bacitracin
2. Cycloserine
3. Vancomycin

Question 20

What are tetracyclines?

Answer 20

Competes with aminoacyl-tRNA for the A site on ribosoems. Oral or parenteral routes, some aren’t absorbed with Ca2+

Question 21

What are tetracyclines the first choice for?

Answer 21

Rickettsial, mycoplasma, chlamydial infections, cholera and plague.

Question 22

What does chloramphenicol do?

Answer 22

Blocks peptidyl transferase which binds to the 50S ribosome subunit. Lipid soluble. Can cause idiosyncratic depression of bone marrow.

Question 23

What do aminoglycosides do?

Answer 23

Generates an abnormal codon, anti-codon recognition leading to misreading of the message. Bacteriacidal. `

Question 24

What are macrolides?

Answer 24

Many membrered lactone ring with sugars attached. Bacteriostatic.

Question 25

What does rifampicin do?

Answer 25

Blocks DNA-dependent RNA polymerase. Bacteriacidal.

Question 26

What do quinolones do?

Answer 26

Inhibit DNA replication. Bacteriacidal. Treating tuberculosis and leptosy.