L02 - Introduction, Overview & Mechanisms of Action of Classes of Antimicrobial Agents

Question 1

What two types of antibiotic inhibit cell wall synthesis? - Give an example

Answer 1

Beta Lactams (Penicillins)
Glycopeptides (Vancomycin)

Question 2

What four types of antibiotics interfere with DNA synthesis and replication? - Give an example

Answer 2

Sulphonamides (Sulphamethoxazole)
Diaminopyrimidines (Trimethoprim)
Quinolones (Ciprofloxacin)
Nitroimidazoles (Metronidazole)

Question 3

What five types of antibiotics inhibit protein synthesis? - Give an example

Answer 3

Macrolides (Erythromycin)
Aminoglycosides (Gentamicin)
Tetracyclines (Doxycycline)
Lincosamides (Clindamycin)
Rifamycins (Rifampicin)

Question 4

What types of antibiotics disrupt the cell membrane? - Give an example

Answer 4

Polymixins (Colistin)

Lipopeptides (Daptomycin)

Question 5

Give three examples of Beta Lactam antibiotics

Answer 5

Penicillins
Cephalosporins
Carbapenems

Question 6

Give two examples of Glycopeptide antibiotics

Answer 6

Vancomycin

Teicoplanin

Question 7

What are the three main types of Beta Lactam structure? - Give an example

Answer 7

Thiazolidine Ring - Penicillins
Dihydrothiazine Ring - Cephalosporins
Carpaneme Core - Carbapenems

Question 8

Describe the features of a Thiazolidine Ring Beta Lactam antibiotic

Answer 8

Ring is 3 carbons, 1 nitrogen, 1 sulphur

Modifiable residue to increase stability/spectrum

Question 9

Describe the features of a Dihydrothiazine Ring Beta Lactam antibiotic

Answer 9

Ring is 4 carbons, 1 nitrogen, 1 sulphur

2 modifiable residues to increase stability/spectrum

Question 10

Describe the features of a Carbapenem Core Beta Lactam antibiotic

Answer 10

Ring is 4 carbons, 1 nitrogen

3 modifiable residues to increase stability/spectrum

Question 11

Describe how Gram staining distinguishes between bacteria

Answer 11

Gram +ve bacteria (blue) have a thick cell wall

Gram -ve bacteria (red) have a thin cell wall with 2 membranes (outer and inner)

Question 12

Name and describe the two types of Gram +ve cocci

Answer 12

Staphylococci (Clumps)

Streptococci (Strips)

Question 13

Name and distinguish the two types of Staphylococci

Answer 13

S. aureus (coagulase +ve)

Coagulase Neg Staph (coagulase -ve)

Question 14

Name and distinguish the three types of Streptococci

Answer 14

Beta Haemolytic (Complete breakdown of blood)
Alpha Haemolytic (Partial breakdown of blood)
Non Haemolytic (No breakdown of blood)

Question 15

Name the three common types of Gram +ve Bacilli

Answer 15

Listeria
Cornyebacterium
Clostridium

Question 16

Give two examples of Gram -ve Cocci

Answer 16

N. meningitidis

N. gonorrhoea

Question 17

Give four examples of Gram -ve Bacilli

Answer 17

Bacteroides
Pseudomonas
Haemophilus
Enterobacteriae

Question 18

Give four examples of Enterobacteriae

Answer 18

E. Coli
Klebsiella
Enterobacter
Proteus

Question 19

Define the atypical bacteria and give two examples

Answer 19

Atypical bacteria do not have a cell wall
Examples are Mycoplasma & Chlamydia
(Cannot treat with a/b that target the cell wall)

Question 20

Describe the MoA of Beta Lactam antibiotics

Answer 20

Bacteria produce cell walls in layers, joined together by amino acid side chains
The chains are linked by Penicillin Binding Protein
Beta Lactams block PBP and expose the cell to osmotic stress

Question 21

What are Beta Lactamases?

Answer 21

Beta Lactamases are bacterially produced compounds that confer antibiotic resistance

Question 22

How do Beta Lactamases confer antibiotic resistance? - And how can we avoid this?

Answer 22

Beta Lactamases hydrolyse the Beta Lactam ring, causing inactivation
We can co-administer Beta Lactamase inhibitors to avoid resistance (Clavulanic Acid)

Question 23

Describe the MoA of Glycopeptide antibiotics

Answer 23

Glycopeptide antibiotics bind to the amino acid side chains on cell wall layers, preventing the binding of PBP

Question 24

Give two examples of Macrolide antibiotics

Answer 24

Erythromycin

Clarithromycin

Question 25

Give two examples of Tetracycline antibiotics

Answer 25

Doxycycline | Tigecycline

Question 26

Give three examples of Aminoglycoside antibiotics

Answer 26

Gentamicin Amikacin Tobramycin

Question 27

Describe the structure of Macrolide antibiotics and their target

Answer 27

Large 'macro' ring structure forms the core Target the 50s Ribosome subunit Many chemical derivatives

Question 28

Describe the structure of Tetracycline antibiotics and their target

Answer 28

Four 'tetra' ring structure Target the 30s Ribosome subunit Avoid in pregnancy/children (teeth discolouration)

Question 29

Describe the structure of Aminoglycoside antibiotics

Answer 29

Three rings linked via oxygen residues Target the 30s Ribosome subunit Narrow therapeutic window (toxicity)

Question 30

What two types of antibiotics target Nucleotide Synthesis? - Give an example

Answer 30

Sulphonamides (Sulphamethoxazole) | Diaminopyrimidines (Trimethoprim)

Question 31

What type of antibiotics inhbits DNA Gyrase? - Give an example

Answer 31

Quinolones (Ciprofloxacin)

Question 32

What is the MoA of Sulphonamides and Diaminopyrimidines?

Answer 32

Sulphonamides/Diaminopyrimidines act as Folate Synthesis inhibitors Avoid Diaminopyrimidines in 1st trimester

Question 33

What is the MoA of Quinolones (and Fluoroquinolones)?

Answer 33

Quinolones/Fluoroquinolones stop DNA unwinding before replication

Question 34

Define Fungi and describe their grouping

Answer 34

Fungi are eukaryotic cells, grouped as: Yeasts Moulds Dimorphic

Question 35

What are the main types of Antifungals? - Give an example

Answer 35

Azoles (Fluconazole) Polyenes (Amphotericin B) Echinocandins (Caspofungin)

Question 36

What are the two types of Azoles?

Answer 36

Triazoles | Imidazoles

Question 37

Give two examples of Triazoles

Answer 37

Fluconazole | Voriconazole

Question 38

Give two examples of Imidazoles

Answer 38

Clotrimazole | Miconazole

Question 39

Give two examples of Polyenes

Answer 39

Amphotericin B | Nystatin

Question 40

Give two examples of Echinocandins

Answer 40

Caspofungin | Micafungin

Question 41

Describe the structure & MoA of Triazoles

Answer 41

Triazole rings have 2 carbons, 3 nitrogens | They inhibit ergosterol synthesis via Lanosterol (essential for fungal cell membranes)

Question 42

Describe the structure & MoA of Polyenes

Answer 42

Polyenes are macrocyclic and form C=C | They bind ergosterol (essential for fungal cell membranes)

Question 43

Describe the structure & MoA of Echinocandins

Answer 43

Echinocandins are macrocyclic with a carbon tail | They inhibit glucan synthesis in the cell wall

Question 44

Give four examples of human mycoses

Answer 44

``` Tinea Candidiasis Mucormycosis Aspergillosis (Moving superficial to deep) ```