Antibiotics and Resistance

Question 1

What are the 3 main classes of Abx that interfere with cell wall synthesis?

Answer 1

1. Beta lactams
2. Glycopeptides
3. Polymyxins

Question 2

Give examples of Beta- lactams?

Answer 2

Penicillins
Cephalosporins
Carbapenems

Question 3

Give examples of glycopeptides?

Answer 3

Vancomycin

Teicoplanin

Question 4

Give an example of a polymyxins?

Answer 4

Colistin

Question 5

What 3 Abx act on folate synthesis?

Answer 5

1. Sulfamethoxazole - which inhibits PABA –> DHFA
2. Trimethoprim - which inhibits DHFA –> THFA
3. co-trimoxazole is a combination of sulfamethoxazole and trimethoprim

Question 6

What are the different classes of Abx that target nucleic acid synthesis?

Answer 6

1. Abx that acts on folate synthesis
2. Abx that act on DNA synthesis
3. and Abx that act on RNA polymerase.

Question 7

Give examples of Abx that act on DNA synthesis?

Answer 7

1. Fluoroquinaolones

2. Metronidazole

Question 8

Give an example of an Abx that acts on RNA polymerase?

Answer 8

Rifamycins

Question 9

What are the 2 main classes of Abx that act on protein synthesis?

Answer 9

50s ribosomal subunit targets and 30s ribosomal subunit targets.

Question 10

What are the 2 forms of Abx resistance?

Answer 10

1. Intrinsic - due to inherent structural or functional characteristics e.g. vancomycin cannot cross the outer membrane of gram-negative organisms
2. Acquired - Bacteria have been evolving to resist antibacterial agents through mutation and/or the transfer of resistance properties.

Question 11

Bacteriostatic

Answer 11

Means that the Abx stops the reproduction and growth of bacteria

Question 12

Bactericidal

Answer 12

Means that the Abx kills the bacterial directly

Question 13

Which antibiotics act in the cell wall synthesis of a bacteria?

Answer 13

Penicillins 
Carbapenems 
Vancomycin 
Teicolanin 
Cephalosporins

Question 14

Which antibiotics word on DNA synthesis of a bacteria

Answer 14

Metronidazole

Question 15

Which antibiotics work on ribosomes

Answer 15

Erythromycin
Clindamycin
Tetracycline
Gentamicin

Question 16

Which Abx works on the conversion of PABA to DHFA in the synthesis of folic acid?

Answer 16

Sulfamethoxazole

Question 17

Which Abx works on the conversions of DHFA to THFA in the synthesis of folic acid?

Answer 17

Trimethoprim

Question 18

Which Abx inhibit cell wall synthesis and have a beta-lactam ring?

Answer 18

• Penecillin
• Carbapenems such as meropenem
• Cephalosporins

Question 19

Which Abx inhibit cell wall synthesis and do not have a beta-lactam ring?

Answer 19

• Vancomycin

* Teicoplanin

Question 20

Folic acid synthesis?

Answer 20

This chain starts with para-aminobenzoic acid (PABA), which is directly absorbed in to the cell across the cell membrane. PABA is then converted to dihydrofolic acid (DHFA), then tetrahydrofolic acid (THFA) and finally folic acid.

Question 21

Mechanism of action of metronidazole

Answer 21

The reduction of metronidazole into its active form only occurs in anaerobic cells. When partially reduced metronidazole inhibits nucleic acid synthesis. This is why metronidazole is effective against anaerobes and not aerobes.

Question 22

Abx that inhibit protein synthesis by targeting the ribosome

Answer 22

Macrolides such as erythromycin, clarithromycin and azithromycin
Clindamycin
Tetracyclines such as doxycycline
Gentamicin
Chloramphenicol

Question 23

What are people with penicillin allergies sometimes also allergic to?

Answer 23

It is often believed that 10% of patients with penicillin allergy will have a reaction to cephalosporins and carbapenems. In reality this is closer to 1%.

Question 24

Stepwise method of remembering Abx

Answer 24

Start with amoxicillin which covers streptococcus, listeria and enterococcus
Switch to co-amoxiclav to additionally cover staphylococcus, haemophilus and e. coli
Switch to tazocin to additionally cover pseudomonas
Switch to meropenem to additionally cover ESBLs
Add teicoplanin or vancomycin to cover MRSA
Add clarithromycin or doxycycline to cover atypical bacteria

Question 25

Penicillins

Answer 25

``` Pen V Amoxicillin Flocloxicillin Benzyl penicillin Co-amoxiclav Tazocin ```

Question 26

Cephalosporins

Answer 26

Ceftriaxon

Question 27

Carbapenems

Answer 27

Meropenem

Question 28

Diaminopyramidine

Answer 28

Trimethoprim

Question 29

Macrolides

Answer 29

Erythromycin Clarithromycin Azithromycin

Question 30

Lincosamides

Answer 30

Clindamycin

Question 31

Aminoglycosides

Answer 31

Gentamicin

Question 32

Quinolones

Answer 32

Ciprofloxacin | Levofloxacin

Question 33

Glycopeptides

Answer 33

Vancomycin | Teicoplanin

Question 34

Nitroimidazoles

Answer 34

Metronidazole

Question 35

Tetracyclines

Answer 35

Doxycycline

Question 36

What Abx can be used to treat staph aureus

Answer 36

``` Flucloxacillin Co-amoxiclav Tazocin Ceftriaxon Meropenem Erythromycin Clarithromycin Azithromycin Clindamycin Gentamicin Ciprofloxacin Levofloxacin Vancomycin Teicoplanin Doxycycline ```

Question 37

What Abx can be used to treat MRSA?

Answer 37

Gentamicin Vancomycin Teicoplanin Doxycycline

Question 38

What Abx can be used to treat beta-haem strep

Answer 38

``` All except: Trimethoprim Gentamicin Ciprofloxacin Levofloxacin Metronidazole Doxycycline ```

Question 39

What Abx can be used to treat Strep pneumon

Answer 39

``` All except: Flucloxacillin Trimethoprim Gentamicin Ciprofloxacin Metronidazole ```

Question 40

What Abx can be used to treat enterococcus

Answer 40

``` Amoxicillin Benzyl penecillin Co-amoxiclav Meropenem Vancomycin Teicoplanin ```

Question 41

What Abx can be used to treat Neisseria meningitidis

Answer 41

Benzyl penecillin Ceftriaxon Meropenem

Question 42

What Abx can be used to treat harm influenza

Answer 42

``` Co-amoxiclav Tazosin Ceftriaxon Meropenem Ciprofloxacin Levofloxacin Doxycycline ```

Question 43

What Abx can be used to treat E. coli

Answer 43

``` Co-amoxiclav Tazosin Ceftriaxon Meropenem Trimethoprim Gentamicin Ciprofloxacin Levofloxacin ```

Question 44

What Abx can be used to treat ESBL

Answer 44

Meropenem

Question 45

What Abx can be used to treat pseudomonas aeruginosa

Answer 45

``` Tazosin Meropenem Gentamicin Ciprofloxacin Levofloxacin ```

Question 46

What Abx can be used to treat moraxella catarrhalis

Answer 46

``` Tazocin Ceftriaxon Meropenem Gentamicin Ciprofloxacin Levofloxacin Doxyclycline ```

Question 47

What Abx can be used to treat anaerobes

Answer 47

``` Pen V Amoxicillin Flucloxacillin Co-amoxiclav Tazocin Meropenem Clindamycin Metronidazole Doxycycline ```

Question 48

What Abx can be used to treat Atypicals

Answer 48

``` Erythromycin Clarithromycin Azithromycin Ciprofloxacin Levofloxacin Doxycycline ```