Antibiotics

Question 1

5 main mechanisms for anti-microbials

Answer 1

1. Inhibiting cell wall synthesis - B-lactam a, vancomycin
2. Inhibiting nuclei acid synthesis - fluroquinolones, rifamycins
3. Stopping metabolite production - fluroquinolones, rifamycins
4. Ihinting cell membrane synthesis - daptomycin
5. Inhibiting protein synthesis - linezolid, tetracyclines, macrolides, aminoglycosides

Question 2

Difference between bactericidal and bacteriostatic

Answer 2

Bactericidal - destroying or killing bacteria (work optimally normal rapidly dividing bacteria)

Bacteriostatic - stop divisions & replication of bacteria, slow growth, still alive & rely on body’s usual mechanisms

Question 3

For the class of penicillin, give examples, mechanism and static or cidal?

Answer 3

Amoxicillin
Flucloxicillin

Cell wall

Bactericidal

Question 4

For the class of ceflasporins, give examples, mechanism and static or cidal?

Answer 4

Ceftriaxone
Cephalexin

Cell wall

Bactericidal

Question 5

For the class of quinolones , give examples, mechanism and static or cidal?

Answer 5

Ciprofloaxin
Levofloxacin

DNA/ RNA synthesis

Both depends dose/ infection

Question 6

For the class of macrolides, give examples, mechanism and static or cidal?

Answer 6

Erythromycin
Clarythromycin

Protein synthesis

Bacteriostatic

Question 7

For the class of tetracycline, give examples, mechanism and static or cidal?

Answer 7

Doxycline

Protein synthesis

Bacteriostatic

Question 8

For the class of aminoglycosides, give examples, mechanism and static or cidal?

Answer 8

Gentamicin

Protein synthesis

Both

Requires monitoring

Question 9

For the class of glycopeptides, give examples, mechanism and static or cidal?

Answer 9

Vancomycin

Cell wall

Bactericidal

Requires monitoring

Question 10

For the class of carbopenams , give examples, mechanism and static or cidal?

Answer 10

Meropenem

Cell wall

Bactericidal

Question 11

4 mechanisms of drug resistance and examples

Answer 11

Efflux pumps e.g. fluroquinolones, aminoglycosides, tetracyclines, b-lactams, macrolides

Immunity & bypass - tetracyclines, trimethoprim, sulfonamides, vancomycin

Target modification - fluroquinolones, rifamycins, vancomycin, penicillins, macrolides, aminoglycosides

Inactivating enzymes - b-lactams, aminoglycosides, macrolides, rifamycins

Question 12

Why do we need to monitor drugs? Give an example

Answer 12

Narrow therapeutic window
Max effect of antibiotic
Risks of toxicity

E.g. vancomycin blood test every 4th dose before 5th is due

Question 13

Difference between time-dependant and concentration- dependent antibiotics

Answer 13

Time- dependant: higher concentration of drug does not result in greater killing, long half lives and spend longer at binding site. The concentration exceeds the minimum inhibitory concentration of the microorganism

Concentration- dependent: the higher the concentration the greater the effect (to a point), need a certain concentration at binding sites to be effective. Optimal when = or higher to X10 the minimum inhibitory concentration of the microorganism

Question 14

What is co-amoxiclav made up of? Why is it given in this way?

Answer 14

Made up of clavulanic acid (inhibits effect something beta lactamase enzymes so amoxicillin can work better) & amoxicillin (acts on cell walls of bacteria)

Synergistic effect

Question 15

What factors govern antibiotic choice?

Answer 15

Likely source of infection
Common groups of bacteria
High risk patient
Trends, previous results, resistance

Special groups:
Hepatic, renal Impairment, pregnancy

Allergies
Reactions

Question 16

Anti- microbial treatment and i-fiving patients

Answer 16

Start broad/ empirical treatment then narrow to more appropriate antibiotics, restricted antibiotics need authorisation form microbiology department

Identify (A to F - abroad, blood bourne virus, colonised, diarrhoea (&v), expectorating (cough), funny looking rash 
Isolate
Investigate
Inform 
Initiate treatment

Question 17

When to give aciclovir and how is it given?

Answer 17

To treat herpes simples - non genital:
By mouth
Adults: 200mg 5/day usually for 5 days (longer if new lesion appears or healing incomplete)

If immunocompromised or absorption is impaired:
Adults - 400mg 5times/ day usually for 5 days

Oral- type 1 (mouth ulcers)
Topical - type 2 (genital ulcers)