Antimicrobial Chemotherapy

Question 1

What are the seven principles of prescribing?

Answer 1

1. Indications for antimicrobials
2. Making a clinical diagnosis
3. Patient characteristics
4. Antimicrobial selection
5. Regimen selection
6. Liaison with laboratory
7. Antimicrobial stewardship

Question 2

What are the two indications for using antimicrobials?

Answer 2

• Therapy (to treat)

- Prophylaxis (to prevent)

Question 3

What is empiric therapy?

Answer 3

Treatment without microbiology results.

Question 4

What is directed therapy?

Answer 4

Treatment based on microbiology results.

Question 5

What is the difference between primary and secondary prophylaxis?

Answer 5

Primary prophylaxis prevents a patient from getting an infection in the first place, whereas secondary prophylaxis prevents a second episode of infection.

Question 6

Which patient characteristics may affect prescribing? (6)

Answer 6

• Age
• Renal function
• Liver function
• Immunocompromised
• Pregnancy
• Known allergies

Question 7

What is the mechanism of action of bactericidal antimicrobials?

Answer 7

They act on the cell wall to kill the organism.

Question 8

What is the mechanism of action of bacteriostatic antimicrobials?

Answer 8

They inhibit protein synthesis to prevent colony growth.

Question 9

What are the advantages of using single drug therapy? (3)

Answer 9

• Simpler
• Fewer side effects
• Fewer drug interactions

Question 10

What are the indications for using combination therapy? (3)

Answer 10

• HIV and TB
• Severe sepsis
• Mixed organisms

Question 11

What are the indications for administering a drug orally? (5)

Answer 11

• Patient not vomiting
• Normal GI function
• No shock
• No organ dysfunction
• Adequate oral bio-availability (how much drug is absorbed)

Question 12

What are the indications for administering a drug intravenously? (2)

Answer 12

• Severe/deep-seated infection

- When oral route is not reliable (i.e. due to impaired GI function, vomiting, etc)

Question 13

What are common adverse effects of drugs? (11)

Answer 13

• Allergic reactions
• GI symptoms
• Candida infection (thrush)
• Liver toxicity
• Renal toxicity
• Ototoxicity
• Optic neuropathy
• Convulsions
• Peripheral neuropathy
• Bone marrow toxicity
• Megaloblastic anaemia

Question 14

How would an immediate hypersensitivity allergic reaction manifest itself?

Answer 14

Anaphylactic shock

Question 15

In what ways could a delayed hypersensitivity allergic reaction manifest itself? (5)

Answer 15

Maculopapular rash
Drug fever
Serum sickness
Erythema nodosum
Steven-Johnson syndrome

Question 16

What are the roles of the laboratory in influencing antimicrobial use? (3)

Answer 16

• Carrying out culture/direct detection/serology of appropriate specimens
• Sending out results (preliminary, sensitivity, final)
• Monitoring disease activity and therapeutic level of drug

Question 17

What is antimicrobial stewardship?

Answer 17

Making the best use of our current antimicrobials.

Question 18

How is antimicrobial stewardship achieved? (3)

Answer 18

• Antimicrobial guidelines and policies
• Audit of quality of antimicrobial prescribing
• Education

Question 19

What are the classes of antimicrobials? (10)

Answer 19

• Penicillins (beta-lactams)
• Cephalosporins (beta-lactams)
• Aminoglycosides
• Macrolides
• Quinolones
• Glycopeptides
• Other antibiotics
• Antifungals
• Antivirals
• Immunoglobulin

Question 20

What are the three mechanisms of action of antibiotics?

Answer 20

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

Question 21

Which classes of antibiotics work by inhibiting cell wall synthesis?

Answer 21

Glycopeptides and beta-lactams (penicillins and cephalosporins)