Introduction to antibiotics

Question 1

Define antibiotic

Answer 1

Anti-bacterial medication (not including disinfectants)

Question 2

Define bactericidal and bacteriostatic.

Answer 2

Bactericidal - kills bacteria (affects bac cell wall)

Bacteriostatic - inhibits growth of bacteria (affects RNA/DNA)

Question 3

What is difference between broad spectrum and narrow spectrum antibiotics?

Answer 3

Broad spectrum are active against many bacteria (normally kill flora)
Narrow spectrum are active against few bacteria (may not kill pathogens)

Question 4

State the 4 antibiotic mechanisms (e.g. bacteriostatic/cidal) and their targets.

Answer 4

Cell wall - bactericidal
RNA & protein synthesis - bacteriostatic
DNA structure & function - bactericidal if high dose
Folic acid synthesis - bacteriostatic

Question 5

What (type of) antibiotics can you give to target bacterial cell walls?

Answer 5

Beta-lactams (pencillin, cephalosporins):

Flucloxacillin, Benzylpenicillin, Amoxicillin, co-amocixlav

Question 6

What (type of) antibiotics can you give to target bacterial RNA & protein synthesis?

Answer 6

Macrolides - Erythromycin

Question 7

What (type of) antibiotics can you give to target bacterial DNA structure & function?

Answer 7

Quinolones (Ciprofloxacin) and Nitromidazoles (Metronidazole)

Question 8

What (type of) antibiotics can you give to target bacterial folic acid synthesis?

Answer 8

Trimethoprim

Question 9

What can the follow penicillins treat?

Flucloxacillin, Benzylpenicillin, Amoxicillin, co-amoxiclav

Answer 9

Flucloxacillin - Tonsillitis
Benzylpenicillin - LRTI
Amoxicillin - SSTI
co-amoxiclav - mixed infections
0.05% anaphylaxis rate

Question 10

How effective is ceftriaxone at killing bacteria compared to its other generations. What can it be used to treat?

Answer 10

Later gen - inc spectrum of activity but also kill more natural flora
Uses - abdominal sepsis/ bacterial meningitis, orthopaedic inf.

Question 11

What are the uses of erythromycin?

Answer 11

URTI, LRTI, SSTIs (in place of pencillin)
Atypical LRTIs (intracellular organisms) - only time we can use macroglides instead of penicillin

Question 12

What can you use to treat gram -ve (excluding anerobes) and MRSA infections?

Answer 12

Ciprofloxacin

Question 13

What can you use to treat anaerobic infections (abscesses)?

Answer 13

Metronidazole

Question 14

What is trimethoprim used to treat?

Answer 14

Uncomplicated UTIs (not in pregnant women) - Antifolates

Question 15

What factors affect antibiotic choice?

Answer 15

Organism - sensitive/resistant
Patient - immunocompromised, allergy, route, renal/liver function, age/ethic, other drugs?
Then choose ab, dose, route and duration

Question 16

Describe the role of antibiotic guidelines.

Answer 16

BNF has guidelines but most organisations develop their own
Based on local epidemiology, ab resis, cost
Aim - effective/efficient treat
Reduce over-prescribing
Reduce emperical ab use (lead to resistance, adverse effects and ab-related infec)