Module 6: Antimicrobial Agents

Question 1

Antimicrobial Agent

Answer 1

A type of chemotherapeutic agent used specifically for the treatment of infectious diseases. Most antimicrobial agents are antibiotics but not all of them are

Question 2

Antimicrobial Agents Spectrum(s)

Answer 2

Broad spectrum–> Affects a wide variety of microorganisms. Gram+ and Gram- bacteria Narrow spectrum–> Affects a small group of microorganisms Gram+ OR Gram-

Question 3

Antimicrobial Agents, Bactericidal or Bacteriostatic

Answer 3

Bactericidal–> Agent actually kills the bacteria Bacteriostatic–> Agent only prevents the bacteria from multiplying

Question 4

Antimicrobial Agents Mode of Action

Answer 4

1. inhibitors of cell wall synthesis 2. inhibitors of protein synthesis 3. inhibitors of DNA and RNA synthesis 4. inhibitors of cell membrane functions 5. inhibitors of other metabolic processes

Question 5

Criteria for an antibiotic in order for it to be used clinically

Answer 5

-should have selective toxicity, allowing it to selectively kill microorganisms and not host cells -shouldn’t cause allergic reactions in the patient -should be soluble in body fluids and be capable of penetrating infected tissue -microorganisms shouldn’t readily develop resistance to the antibiotic

Question 6

Natural Penicillins

Answer 6

Original compounds extracted from the mold, Penicillium

Question 7

Penicillins bacterial resistance

Answer 7

Inactivated or sensitive against beta-lactamase, an enzyme that opens the beta-lactam ring and makes the antibiotic useless.

Question 8

Penicillins clinical use

Answer 8

Penicillin G= not taken orally Penicillin V= can be given orally Natural penicillins are sometimes given with other drugs to improve absorption and retention properties of the penicillin

Question 9

Penicillin mode of action

Answer 9

Bactericidal- kills bacteria Inhibits cell wall synthesis

Question 10

Examples of Penicillins

Answer 10

Penicillin G and Penicillin V

Question 11

Beta-Lactamase Resistant Penicillins

Answer 11

Oxacillin Methicillin Cloxacillin

Question 12

Beta-Lactamase Resistant Penicillins

Answer 12

A “bulky” side chain was added to the penicillin core that protects the beta-lactam ring from enzymatic destruction

Question 13

Beta-Lactamase Resistant Penicillins mode of action

Answer 13

Beta-lactam cell wall inhibitor

Question 14

Beta-Lactamase Resistant Penicillins spectrum

Answer 14

Very narrow Gram + spectrum Mainly used for treatment of Staphylococcal Infections

Question 15

Beta-Lactamase Resistant Penicillins bacterial resistance

Answer 15

Not inactivated by beta-lactamase Resistance from penicillin binding proteins

Question 16

Beta-Lactamase Resistance Penicillins clinical use

Answer 16

Orally or injected, Cloxacillin is most common

Question 17

Extended Spectrum Penicillins

Answer 17

In the group of penicillins the Extended Spectrum Penicillins like Aminopenicillins are now a broad spectrum that includes gram- organisms

Question 18

Beta-Lactamase Resistant Penicillins class concept

Answer 18

Applies

Question 19

What is the spectrum of Extended Spectrum Penicillins?

Answer 19

Broad spectrum

Question 20

Extended Spectrum Penicillins mode of action

Answer 20

Inhibiting synthesis of the bacterial cell wall

Question 21

Extended Spectrum Penicillins spectrum

Answer 21

Broad spectrum Treatment of infections from both Gram+ and Gram- bacteria

Question 22

Extended Spectrum Penicillins bacterial resistance

Answer 22

Susceptible to beta-lactamase and inactivated by these enzymes

Question 23

Two Groups of Anti-Pseudomonal Penicillins

Answer 23

1. Carboxy Pencillins (carbenicillin, ticarcillin) 2. Ureidopenicillins (azlocillin, mexlocillin, pipercillin)

Question 24

Anti-Pseudomonal Penicillins Spectrum

Answer 24

Broad, less active against Gram+ than natural penicillins

Question 25

Anti-Pseudomonal Penicillins Bacterial Resistance

Answer 25

Inactivated by staphylococcal beta-lactamase but more stable against Pseudomonas and Enterobacteriacea beta-lactamase

Question 26

Anti-Pseudomonal Penicillins Clinical Use

Answer 26

Very expensive, used when bacteria are resistant to other antibiotics Often given with aminogylcosides, the combination is used for pseudomonal infections

Question 27

Cephalosporins

Answer 27

-second group of the Beta-Lactam antibiotics -nucleus contains a beta-lactam ring fused to a different structure than the one in penicillins -over 20 of them developed for clinical use -Cephalosporins are placed in four groups based on their spectrum

Question 28

Cephalosporins First Gen. Spectrum

Answer 28

Broad

Question 29

First Gen. Clinical Use

Answer 29

More expensive than penicillins Cephalothin and Cefazolin are injected but Cephalexin can be taken orally

Question 30

Cephalosporin Second Gen. Examples

Answer 30

Cefaclor Cefamandole Cefonicid Ceforanide Cefotiam Cefuroxime Cefotetan Cefoxitin

Question 31

Cephalosporin Second Gen. Spectrum

Answer 31

Broad Individual antibiotics in this group are effective against specific organisms but not effective against Pseudomonas