Antimicrobial Introduction

Question 1

What is selective toxicity?

Answer 1

Ideal antimicrobial agent acts selectively on the pathogen, not the host.

Question 2

What is the difference between bactericidal and bacteriostatic activity?

Answer 2

Bactericidal –> cell killing, when you remove the antimicrobial there is no bacterial growth
Bacteriostatic –> inhibition of cell growth, reversible, post antibiotic effect possible

Question 3

What classes of antimicrobials are considered bactericidal?

Answer 3

Cell wall synthesis inhibitors, membrane damage, DNA damage

**Aminoglycosides (protein synthesis inhibitor)

Question 4

What classes of antimicrobials are considered bacteriostatic?

Answer 4

Protein synthesis inhibitors (except ahminoglycosides) and antimetabolites

Question 5

What does MBC stand for?

Answer 5

Minimal Bactericidal Concentration

Question 6

What does MIC stand for?

Answer 6

Minimal Inhibitory Concentration

Question 7

What does it mean for an antibiotic to be concentration-dependent?

Answer 7

Antibiotic effectiveness is dependent on achieving peak concentration periodically in multiple dosing regimen (Cpeak/MIC)
**allows for longer dosing interval

Question 8

What does it mean for an antibiotic to be time-dependent?

Answer 8

Antibiotic effectiveness is dependent on time (%) that concentration remained above MIC (Time>MIC)
Ex: CWS produce slow killing, requiring maintained cocentrations
**requires small dosing intervals relative to half-life

Question 9

What does it mean for an antibiotic to be concentration-dependent with time-dependent action?

Answer 9

Antibiotic effectiveness is dependent on both concentration and time of exposure in the dosing interval (AUC24h/MIC)

Question 10

What is the post antibiotic effect?

Answer 10

Persistent suppression of microbial growth after antimicrobial agent as been cleared
**can make length of dosing interval less of a concern

Question 11

What does
1) Narrow spectrum
2) Extended spectrum
3) Broad spectrum
mean?

Answer 11

1) effective against EITHER Gram + or Gram -
2) effective against a variety of Gm+ and Gm -
3) effective against both Gm+, G-. and other microorganisms

Question 12

1) What are the ways a bacteria can become resistant?

2) Can genetic resistance mechanism be transmissible between organisms?

Answer 12

1) Misdiagnosis, Intrinsic microbial resistance, or acquired microbial resistance –> drugs fail to reach target, drug is inactivated, drug target is altered.
2) Yes

Question 13

1) What is definitive antimicrobial therapy?

2) What is empirical antimicrobial therapy?

Answer 13

1) identification of specific pathogen prior to treatment

2) treatment without formal identification of specific pathogen

Question 14

What are the general adverse effects that can come from antimicrobial therapy?

Answer 14

Allergy, superinfection, organ toxicity, selection of resistant microrganisms

Question 15

1) What percent of antibiotics are used for prophylaxis?

2) What are some of the common reasons for antibiotic prophylaxis?

Answer 15

1) 30-50% of administered antibiotics are for prophylaxis
2) Recommended for many surgical procedures and dental procedures: prevent wound infection and for patients with indwelling medical devices
Also for STI prophylaxis for sexual contact