Infections II: Bacterial Infections, Antibacterial Agents & Mechanism of Action

Question 1

What are antibiotics also known as?

Answer 1

Antibacterial drugs

Question 2

Define: Antibiotics/Antibacterial drugs

Answer 2

Drugs used to treat infections caused by bacteria

Question 3

Define: Bacterial infection

Answer 3

An infection caused by a bacterium

Question 4

List 3 symptoms of bacterial and viral infection

Answer 4

1. Malaise
2. Fever
3. Chills

Question 5

What should antibiotics not be prescribed to treat?

Answer 5

Viral infections

Question 6

Describe the structure of a gram postive bacterium

Answer 6

Simple structure

Peptidoglycan (50%) and cell membrane

Question 7

Describe the structure of a gram negative bacterium

Answer 7

More complex structure than gram positive
Cell membrane - Periplasmic space - Peptidoglycan - Outer membrane layer containing phospholipids and complex polysacchardies (e.g. lipo-)

Question 8

What does AMR stand for?

Answer 8

Antimicrobial resistance

Question 9

Define: Bacteriostatic

Answer 9

A biological or chemical agent which prevents the bacteria from reproducing, while not necessarily killing them
So prevents growth of bacteria and keeps them in stationary phase

Question 10

Define: Bactericidal

Answer 10

Kills the bacteria

Question 11

Give 2 examples of bacteriostatic drugs

Answer 11

Chloramphenicol

Erythromycin

Question 12

Give 2 examples of bactericidal drugs

Answer 12

Beta-lactams

Metronidazole

Question 13

How do tetracyclines and macrolides work?

Answer 13

Inhibit protein synthesis

Question 14

How do metronidazole and fluoroquinolones work?

Answer 14

Inhibit DNA synthesis

Question 15

How do sulphonamides and trimethoprim work?

Answer 15

Inhibit folic acid synthesis
Carry out important functions within the cell
(Synthesise, repair and methylate DNA)
Used to treats UTIs and eye infections

Question 16

How do rifampicin and macrocyclines wok?

Answer 16

Inhibit RNA synthesis

Question 17

Name 2 drugs that interferes with the synthesis or action of folate/folic acid

Answer 17

Trimethoprim
Sulphonamides
Work well together - they inhibit the same metabolic pathway at different levels

Question 18

List 3 unwanted effects that trimethoprim can have

Answer 18

Nausea
Vomiting
Folate deficiency, with resultant megaloblastic anaemia - can be prevented by giving folic acid

Question 19

Name 2 uses of trimethoprim

Answer 19

UTIs

Respiratory infections

Question 20

What is the mechanism of action of trimethoprim?

Answer 20

Folate antagonist

Question 21

What is the mechanism of action of sulphonamides?

Answer 21

Competition with PABA = essential precursor in folic acid synthesis in bacteria
Bacteriostatic

Question 22

List 3 unwanted effects of sulphonamides

Answer 22

Allergic reaction
Nausea
Headaches

Question 23

Name 2 sulphonamides

Answer 23

Sulphanilamide

Sulphadiazine

Question 24

Describe the basic chemical structure of sulphonamides

Answer 24

H2N
Benzene ring
O=S=O
NHR

Question 25

What is the mechanism of action of penicillin (beta-lactam antibiotics)?

Answer 25

Interfere with the synthesis of the bacterial cell wall peptidoglycan
Bactericidal

Question 26

List 2 unwanted effects of penicillin

Answer 26

Mostly allergic reactions = rash, fever, anaphylactic shock

GI disturbances

Question 27

Name 3 penicillins and their uses

Answer 27

Flucloxacillin = bone and joint infections, skin and soft tissue infection
Amoxicillin = bronchitis, pneumonia
Benzylpenicillin = more severe infections e.g. bacterial meningitis and skin and soft tissue infection

Question 28

How do beta lactam antibiotics work?

Answer 28

Inhibit cell wall synthesis

Question 29

Name 3 examples of beta lactam antibiotics

Answer 29

Penicillin
Cephalosporins
Carbapenems

Question 30

What is the mechanism of action of cephalosporins

Answer 30

Interfere with bacterial peptidoglycan synthesis after binding to the B-lactam-binding proteins

Question 31

List 3 unwanted effects from cephalosporins

Answer 31

Allergic reaction
Nephrotoxicity
Diarrhoea

Question 32

List 3 clinical uses of cephalosporins

Answer 32

Septicaemia
Meningitis
UTI

Question 33

What is the mechanism of action of tetracyclines?

Answer 33

Inhibits protein synthesis

Bacteriostatic

Question 34

List 3 unwanted effects of tetracyclines

Answer 34

GI disturbances
Hepatotoxicity
Staining growing teeth

Question 35

Name 2 tetracyclines

Answer 35

Tetracycline

Doxycycline

Question 36

Name 2 clinical uses of tetracyclines

Answer 36

Chlamydia

Lyme disease

Question 37

List 3 classes of drug which work by affecting bacterial protein synthesis

Answer 37

Tetracyclines
Chloramphenicol
Macrolides

Question 38

Name a clinical use of chloramphenicol

Answer 38

Bacterial conjunctivitis (topical)

Question 39

What are aminoglycosides used to treat?

Answer 39

Many gram negative, some gram positive

Sepsis

Question 40

Name 2 aminoglycosides

Answer 40

Gentamicin

Streptomycin

Question 41

What are macrolides used to treat?

Answer 41

Same spectrum as penicillins

Safe alternative to penicillins

Question 42

Name 2 macrolides

Answer 42

Erythromycin

Clarythromycin

Question 43

Name 2 clinical uses of quinolones and fluoroquinolones

Answer 43

Complicated UTIs

Gonorrhoea

Question 44

Name 2 classes of drug which target the bacterial cell wall or membrane

Answer 44

Glycopeptides - inhibits cell wall synthesis

Polymyxins - disrupt bacterial cell membrane