Antibiotics 2

Question 1

3. What does the choice of correct antimicrobial depend on?

Answer 1

CHAOS
Host characteristics (e.g. age, pregnancy)
Antimicrobial susceptibility
Organism
Site of infection (e.g. bone, CSF)
NOTE: you should try to use a narrow-spectrum bactericidal drug where possible

Question 2

10. What factors about the site of infection can affect antibiotic choice?

Answer 2

pH at the infection site
Lipid-solubility of the drug
Ability to penetrate the blood-brain barrier

Question 3

11. Which two types of infection require special consideration because they are difficult to penetrate with antibiotics?

Answer 3

Osteomyelitis

Endocarditis

Question 4

12. In which circumstances would you avoid IM administration of antibiotics?

Answer 4

Bleeding tendency

Drug is locally irritant

Question 5

13. Describe the type I pattern of antibiotic activity. Give an example of an antibiotic of this type.

Answer 5

Concentration-dependent killing
Peak above the MIC (Cmax) is the most important parameter
Example: aminoglycosides
These drugs tend to be given as one big dose
The benefits of achieving a higher Cmax must be balanced with the increased toxicity

Question 6

14. Describe the type II pattern of antibiotic activity. Give an example of an antibiotic of this type.

Answer 6

Time-dependent killing
Time spent above the MIC is the most important factor
Example: penicillins
Therefore, penicillins need to be given frequently

Question 7

15. Describe the type III pattern of antibiotic activity. Give an example of an antibiotic of this type.

Answer 7

Concentration and time-dependent
AUC above the MIC is the most important factor
Example: vancomycin
NOTE: infusions may be used to maintain an AUC above the MIC

Question 8

17. Outline the typical length of treatment for:
    a. N. meningitidis meningitis

b. Acute osteomyelitis
c. Bacterial endocarditis
d. Group A streptococcal pharyngitis
e. Simple cystitis

Answer 8

a.	N. meningitidis meningitis
7 days 
b.	Acute osteomyelitis 
6 weeks 
c.	Bacterial endocarditis 
4-6 weeks 
d.	Group A streptococcal pharyngitis 
10 days 
NOTE: needs to be treated for 10 days to reduce the risk of sequelae such as rheumatic fever and glomerulonephritis 
e.	Simple cystitis 
3 days