infections 1 - recap

Question 1

what are the characteristics of Gram + bacteria

Answer 1

Gram +ve
Simple structure
50% peptidoglycan
40-45% acidic polymer
5-10% proteins & polysaccharides

Question 2

what are the characteristics of Gram - bacteria

Answer 2

Gram –ve
More complex
Larger periplasmic space
Thin peptidoglycan layer 5%
Outer membrane
Complex polysaccharides

Question 3

give some examples of gram + bacterias

Answer 3

cocci (round shaped)
bacilli( rod-shaped)

cocci - Staphylococci - clusters- S. aureus
Streptococci - pairs/chain

• check 1 on the note book for full examples

Question 4

Which bacteria are associated with endotoxins

Answer 4

gram negative

Endotoxins are found in the outer membrane of the cell wall of Gram-negative bacteria. They elicit a strong immune response in man (e.g., fever, septic shock), and cannot be removed from materials by normal sterilization processes.

Question 5

Which part of the Gram negative bacteria is considered to be the endotoxin

Answer 5

lipopolysachharide

Question 6

Which part of bacteria binds crystal violet in Gram stain?

Answer 6

peptidoglycan

Question 7

what is the MoA of antibiotics?

Answer 7

1) Cell Wall Synthesis Inhibition (glycopeptide and fosfomycin - inhibit peptidoglycan sythesis)

2) Protein Synthesis Inhibition ( 50S: Macrolides,Clindamycin, Linezolide ,Chloramphenicol ,,,,,, Initiation: Oxazolidinones (Linezolid),,,,30S- Tetracyclines and Aminoglycosides

3) DNA Synthesis Inhibition- (Fluoro)quinolones DNA gyrase or topoisomerase

4) RNA Synthesis Inhibition- Fidaxomicin (a macrocyclic) - binds RNA Polymerase
Rifampin (binds RNA Polymerase)

5) Folate Synthesis Inhibition - Trimethoprim and Sulphonamides

6) Cell Membrane Inhibition - Trimethoprim and Sulphonamides, Fidaxomicin (a macrocyclic) - binds RNA Polymerase and Rifampin (binds RNA Polymerase)

7) Cell Membrane Disruption- Polypeptides:Collistin, Polymyxin and Lipopeptides:
Daptomycin

8) DNA damage/ free radical - metronidazole and nitrofuritonin

9) Mycolic Acid Synthesis inhibition- Isoniazid, Ethionamide, Delaminid

10) ATP synthesis inhibition (only for TB, L3 PM2A2)- Diarylquinolones:
Bedaquiline (TB)

Question 8

Nitrofurantoin acts by:

Answer 8

Causing DNA damage via free radicals

Question 9

Which of the following disrupts the bacterial cell membrane?

Answer 9

daptomycin

Question 10

what is the mechanism of resistance?

Answer 10

1) Reduction in cellular permeability or concentration of antibiotic
Doesn’t allow drug to get to toxic levels in cell
Can be change in cell wall / membrane, antagonism of antibiotic transport processes or generation of an efflux pump

2)Conversion of active drug to inert product by an enzyme – common
Bacteria can produce β-lactamases e.g. penicillinase can convert penicillin to penicilloic acid (not antibacterial)
Clavulanic acid inhibits β-lactamase [in combination with penicillins – Co-amoxiclav = amoxicillin + Clavulanic acid]
Aminoglycosides inactivated by acetyl-, adenyl- or nucleotidyl-transferases
Chloramphenicol can be broken by acetylation (chloramphenicol acetyl transferase)

3) Changes in antibiotic target site resulting in resistance / acquisition resistant form of target enzymes

4)Altered metabolic pathway

Question 11

What is the uk immunesiation shcedule

Answer 11

check week 5 slide 27

Question 12

At what age is the first vaccination on the UK vaccination schedule?

Answer 12

eight weeks old

Question 13

At what age is the last vaccination on the UK vaccination schedule?

Answer 13

70-79 years old

Question 14

how can antimicrobial resistance be tackled?

Answer 14

Reduce need and unintentional exposure to antimicrobials.
Optimise use of antimicrobials.
Invest in innovation, supply and access.