Antimicrobial Chemotherapy

Question 1

Indications for antimicrobials

Answer 1

• Therapy

- Prophylaxis

Question 2

2 types of antimicrobial therapy

Answer 2

• Empiric, without microbiology results

- Directed, based on microbiology results

Question 3

2 types of antimicrobial prophylaxis

Answer 3

• Primary
  Anti-malarial
  Pre-operative surgical
  Post-exposure (HIV, Meningitis)
• Secondary
  To prevent a second episode (Pneumocystis Jiroveci Pneumonia, common in immunosuppressed patients AKA PCP/PJP )

Question 4

What type of antibiotics are bactericidal vs bacteriostatic and when to use them

Answer 4

Cidal = beta-lactams, indicated in neutropenia, meningitis and endocarditis 
Static = macrolides, useful in toxin-mediated illness

Question 5

Benefits/indications of single and combination therapy

Answer 5

Single = Fewer side effects + fewer drug interactions 
Combination = HIV + TB therapy, Severe sepsis (Febrile sepsis), mixed organisms (faecal peritonitis)

Question 6

When to use oral vs IV antibiotics

Answer 6

Oral route - If not vomiting, normal GI function, no shock, no organ dysfunction

IV route - for severe or deep-seated infection, and when oral route is not available

Question 7

Types of adverse effects of antibiotics and example/cause of each

Answer 7

• Allergic reaction
  Immediate hypersensitivity (anaphylactic shock)
  Delayed hypersensitivity (rash, drug fever, serum sickness, erythema nodosum)
• GI (nausea, vomiting, diarrhoea, C-diff)
• Candida (thrush)
• Liver (TB drugs)
• Renal (gent + vanc)
• Neurological
  Otoxicity (gent + vanc)
  Optic neuropathy (ethambutol for TB)
• Haematological (marrow toxicity, megaloblstic anaemia)

Question 8

What 4 antibiotics carry a huge risk of C. diff

Answer 8

THE 4 C’s

• Ceftriaxone (and other cephalosporins)
• Co-amoxiclav
• Clindamycin
• Ciprofloxacin (and other quinolones)

Question 9

6 types of antibiotics

Answer 9

• Penicillins (beta-lactams)
• Cephalosporins (beta-lactams)
• Aminoglycosides
• Macrolides
• Quinolones
• Glycopeptides

Question 10

3 Mechanisms of action of antibiotics

Answer 10

• Inhibition of cell wall synthesis
• Inhibition of protein synthesis
• Inhibition of nucleic acid synthesis

Question 11

What categories of antibiotic inhibit cell wall synthesis

Answer 11

• Beta-lactams (penicillins and cephalosporins)

- Glycopeptides (vancomycin, teicoplanin)

Question 12

What categories of antibiotic inhibit protein synthesis

Answer 12

• Aminoglycosides (gentamycin)
• Macrolides (clarithromycin)
• Tetracyclines (doxycycline)
• Oxazolidinones (linezolid)

Question 13

What categories of antibiotic inhibit nucleic acid synthesis

Answer 13

• Trimethoprim
• Sulphonamides (sulphamethoxazole)
• Quinolones (ciprofloxacin)