Treatment For Infections

Question 1

Define osmotic pressure

Answer 1

O.P of a solution is the external pressure that must be applied to prevent the movement of solvent via osmosis

Question 2

What is the unit for O.P?

Answer 2

Osmoles (Osm)

Milliosmoles (mOsm)

Question 3

What’s the different bw osmolality and osmolarity?

Answer 3

Osmolality: no. Of osmoles/ kg of solvent ie water
Osmolarity: no. Of osmoles/L of solution

Question 4

What’s the normal osmolality for blood?

Answer 4

285 mOsmo/kg

Question 5

Define anti microbial agent

Answer 5

Chemicals which kill (bactericidal) / inhibit (bacteriostatic) microbial growth in or on a body surface

Topical- kill bac on surface
Oral, iV- kill bac inside body

Question 6

What are the three sources of antimicrobials? And which is the most common one?

Answer 6

Micro organism
Synthesis (chloramphenicol)
Semi synthesis* (penicillin=b lactams)

Question 7

What type of bacteria does antimicrobial agent work best on? (Actively dividing or dormant, latent?)

Answer 7

Actively dividing bacteria

Question 8

What are the ideal properties of antibiotics?

Answer 8

Antimicrobial properties for example
Specific, selective, cidal, slow emergence of R

Pharmacological activities: 
Non toxic to host
Long half life
Low plasma protein binding
Good tissue distribution
Oral &parental 
No interactions w other drugs

Question 9

Name the four main sites of action of antibiotics on a bacteria

Answer 9

Cell wall*
Cell mem
Nucleic acid synthesis
Protein synthesis - bacteriostatic

Question 10

Name two cell wall synthesis inhibitors

Answer 10

B lactams* :penicillin, cephalosporins, carbapenems, monobactams
Glycopeptides : vancomycin, teicoplanin

Question 11

Describe the MOA for b lactams e.g. Amoxicillin (penicillin)

Answer 11

1 bind and inhibit action of penicillin binding proteins (PBPs) - transpeptidases–> prevent Xlinking bw neighbouring PG–>cell lysis

2 get incorporated into peptide side chain, prevent X linking - cell lysis

3 stimulate autolysins- break down own cell wall- lysis

Question 12

Describe the MOA for glycopeptides e.g. Vancomycin and teicoplanin

Answer 12

1 bind to D ala, D ala on peptide side chain of monomer
(NAG+NAM+side chain) on outer surface of cell wall
2 prevent glycosylase enzyme from adding PG monomer onto PG chain
3 prevent X linking

Question 13

Name 2 bacterial cell mem inhibitors

Answer 13

Polymyxins E(colistin)

Lipopeptides: daptomycin (cubicin)

Question 14

Describe the MOA for polymyxin C (colistin)

Answer 14

Works on G-ve bac only 
Bind to lipid A of PLS on the OUTER MEM 
Break down permeability of outer mem
Through to cyto
Leakage of cyto content

Question 15

Name 2 drugs that classified as fluoroquinolones

Answer 15

Ciprofloxacin

Levofloxacin

Question 16

What’s the name for type of AB that can inhibit NA replication/ translation

Answer 16

Fluoroquinolones

F group makes quinolone more active

Question 17

Describe the MOA for fluoroquinolones

Answer 17

1 inhibit bacterial DNA replication via -binding to DNA gyrase and /or type 4 topoisomerases
DNA gyrase removes DNA supercooled ahead of replication fork
Topoisomerase 4 separate 2 new DNA strands after replication
2 this inhibits DNA rep and packaging of DNA within bac cell
3 cell lysis

Question 18

Name 2 bacterial cell protein inhibitors

Answer 18

Aminoglycosides

Tetracycline

Question 19

An example drug that’s classified as aminoglycoside

Answer 19

Gentamicin

Question 20

Describe the structure and binding sites of a bacterial ribosomome

Answer 20

50s and 30s subunits
50s: 23S & 5S rRNA + protein

30s: 16S rRNA + protein

A acceptor site
P peptide site
E exit site

Question 21

MOA for aminoglycoside e.g. Gentamicin

Answer 21

1 bind IRREVERSIBLY to the A site on 16s rRNA in 30s subunit
2 causes misreading of codons along the mRNA
3 wrong AA in sequence
4 interferes w translocation of tRNA from A site to P site
5 indirectly disrupt mem permeability
Bactericidal!!! Not common

Question 22

MOA for tetracycline e.g. Doxycycline

Answer 22

Bind REVERSIBLY to A site 
Inhibit binding of tRNA to A site 
Inhibit protein synthesis 
Target also present in human cells, however better uptake by bacterial cells
Bacteria static

Question 23

What are the 4 classes of b lactamase?

Answer 23

Class A : penicillinases e.g. TEM1,2
Class B : Metallo- b lactamases
Class C : cephalosporinase
Class D : ESBL hydrolysing b lactam AB w more variable structures

Question 24

What are the side effects of ciprofloxacin?

Answer 24

GIT - c.difficile
DDI (drugs that are metab by CYP450 in liver)
Cartilage (young)/ tendon (old) damage
Rash, photosensitivity

Question 25

What type of inhibitor is rifamycin? Give a common example

Answer 25

Rifampicin | RNA polymerase inhibitor -bacterialcidal

Question 26

Uses of rifamycin | Is it a semi/fully synthetic AB?

Answer 26

1st line TB along w other AB to reduce R Prophylactic against meningitis Infections of prosthetic joints Endocarditis

Question 27

Describe how metronidazole work

Answer 27

Inactive prodrug get into bac cell Activated by bac enzyme Used to treat infections caused by ANAEROBES e.g. C DIFFICILE Some genital tract infections SSTI dental infections Active metab cause DNA strand breakage

Question 28

How does rifampicin get excreted?

Answer 28

Via bile

Question 29

Who collects data on AB and infections? | What kind of report do they provide

Answer 29

``` ECDC EARS ESAC Surveillance of R of AB Consumption ```

Question 30

U.K. Five year AMR strategy Year Main points

Answer 30

2013-2018 1. Improve knowledge on AMR 2. Stewed the effectiveness of existing AB 3. Develop new AB

Question 31

IV/ oral switch criteria

Answer 31

``` 1 patient improving 2 SER CRP WBC normalise 3 review after 48h 4 able to take oral 5 does Not have deep seated infection e.g. Endocarditis, brain abscess, prosthetic join inf ```

Question 32

AB prescribing and stewardship 5 competencies

Answer 32

1 infection prevention and control 2 ABR and AB 3 prescribing Ab 4 AB stewardship 5 learning and monitoring