antibiotics

Question 1

resistance

Answer 1

-Resistance existed before antibiotics.

-Selection pressure from repeated exposure to antibiotics has greatly increased resistance.

-Emergence of resistance almost inevitably follows a novel agent

Question 2

types of therapy

Answer 2

Guided therapy:
Depends on identifying cause of infection and selecting agent based on sensitivity testing

Empirical therapy:
Best (educated) guess therapy based on clinical/epidemiological acumen
Used when therapy cannot wait for culture

Prophylactic therapy:
Preventing infection before it begins

Question 3

ideal characteristics- target effects

Answer 3

Highly toxic to bacteria causing infection

Penetrate the body area affected by infection

Limit release of toxins from bacteria

Convenient administration

narrow spectrum- narrow range in treatment

Question 4

ideal characteristics- co-lateral damage

Answer 4

Non-toxic to patient

Limited effect on colonising bacteria which reduces:

Mucosal candida
Clostridium difficile infection
Selection of resistant bacteria

Low potential for bacteria to escape treatment through developing resistance

broad spectrum- broad range of treatment

Question 5

antibiotic action- bactericidal

Answer 5

Achieve sterilisation of the infected site by directly killing bacteria

Lysis of bacteria can lead to release of toxins and inflammatory material

Question 6

antibiotic action- bacteriostatic

Answer 6

Suppresses growth but does not directly sterilise infected site

Requires additional factors to clear bacteria- immune mediated killing

Question 7

antibiotic targets

Answer 7

• cell wall peptidoglycan
• metabolism
• DNA
  -ribosomes

Question 8

antibiotic classes

Answer 8

cell wall agents
- penicillin, glycopeptides
other agents
- ribosomes: macrolides, aminoglycosides
- Dna: quinolones
- Metabolism: trimethoprim

Question 9

penicillins

Answer 9

First members of beta-lactam group of antibiotics

Excellent antibiotics with rapid bacterial killing and low toxicity

Chemically produced derivatives have altered pharmacology and antibiotic action

Vary widely in antibiotic spectrum

Question 10

penicillin allergy

Answer 10

10% of patients report penicillin allergy

Only around 1% of patients would have a significant immune mediated reaction to penicillin

Penicillin allergy label is associated with poorer outcomes

Question 11

vancomycin

Answer 11

Large molecule – cannot penetrate Gram negative cell wall
Useful against penicillin resistant bacteria such as MRSA

Question 12

clarithromycin and doxycycline

Answer 12

Highly concentrated within cells- useful against intra-cellular pathogens.
Useful in infections caused by both Gram +ve and Gram –ve organisms (i.e. chest infections)

Question 13

ciprofloxacin

Answer 13

Good broad spectrum of action
Damage to DNA leads to rapid bacterial cell death
Resistance has now become widespread

Question 14

trimethoprim

Answer 14

One of the earliest antibiotics
Resistance has become extremely common
Mostly now used for non-severe urinary tract infection