L27_Mechanisms of Actions of Antibiotics

Question 1

What is the difference between bactericidal and bacteriostatic?

Answer 1

Bactericidal kills, bacteriostatic inhibits further growth.

Question 2

What is a MIC, What is a MBC?

Answer 2

MIC- Minimal Inhibitory Concentration

MBC- Minimal Bactericidal Concentration

Question 3

If you know an MIC, what concentration of antibiotic do you optimally prescribe?

Answer 3

4xMIC

Question 4

Are most antibiotics prescribed bactericidal or bacteriostatic?

Answer 4

Even though some may be bactericidal, most antibiotics are effectively bacteriostatic at the concentrations given.

Question 5

What is the most common class of clinical antibiotics?

Answer 5

Beta-Lactams (i.e. penicillin)

Question 6

What is the mechanism of action of most anti-fungals?

Answer 6

Attack cell membrane

Question 7

What is a downside of broad-spectrum antibiotics?

Answer 7

Shotgun approach. A lot of collateral damage, especially to normal flora

Question 8

What is the only antibiotic that can treat MRSA?

Answer 8

Vancomycin

Question 9

Describe the difference between pharmacokinetics and pharmacodynamics?

Answer 9

Pharmacokinetics encompasses all the ways that the body manipulates a drug, including absorption, distribution, metabolism, and excretion. Pharmacodynamics describes the biochemical and physiological effects of the drug and its mechanism of action on the bacteria.

Question 10

What are the four main classes of cell wall inhibiting antibiotics.

Answer 10

Beta-Lactams, Glycopeptides, Fosfomycin, Daptomycin

Question 11

What is the mechanism of action of Beta-Lactams? Are they bactericidal or bacteriostatic?

Answer 11

They inhibit cell wall synthesis. They bind irreversibly to transpeptidase enzyme (PBPs) and inhibits cross linking of peptidoglycan sheets. They are bactericidal.

Question 12

What are the four main classes of Beta Lactams? Which are the strongest?

Answer 12

Penicillin, Cephalosporins, Monobactams, Carbapenems (Strongest)

Question 13

How does vancomycin work? What type of bacteria is it ineffective against? What class of antibiotic is it?

Answer 13

It binds up D-alanyl-D-Alanine residues to prevent cross linking. Effective only against Gram Pos. It is a glycopeptide.

Question 14

What are the only type of beta lactams that you can use against bacteria that produce extended spectrum beta lactamases (ESBLs)

Answer 14

Carbapenems

Question 15

What are tetracyclines particularly effective against? Are they bacteriostatic or cidal. When are they containdicative?

Answer 15

Chlamydiae, Rickettsiae, and Mycoplasma

(Bacteriostatic and broad spectrum) can cross cell membrane. Dont give to pregnant women or children

Question 16

What is a concern with aminoglycosides?

Answer 16

Toxicity, must monitor peak and trough levels. Can mess up kidneys and hearing

Question 17

What class of bacteria are macrolides, lincosamides, streptogramins, and ketolides effective against?

Answer 17

Gram Positive cocci

Question 18

What is clydamycin’s mechanism of action? What is a concern when using it?

Answer 18

Protein synthesis inhibition, it is a lincosamide. Inducible resistance is a concern.

Question 19

What are Phenicols (Chloramphenicol) used against? What are dangers of it?

Answer 19

Used against many gram pos and neg bacteria in serious infections. Last resort as it is very toxic, especially to bone marrow.

Question 20

What is linezolid mechanism of action and what can it be used against that many other antibiotics cant.

Answer 20

Protein synthesis inhibitor, can be used against MRSA and other multi-drug resistant infections but only as a last resort.

Question 21

What are Ansamycins and Rifamycins commonly used to treat?

Answer 21

Tb

Question 22

Name some drug classes that interfere with cytoplasmic membrane function

Answer 22

Polymyxins, Bacitracin, Anti-fungals

Question 23

Name the two main drug classes used synergistically to kill bacteria by inhibiting metabolic activity/pathways

Answer 23

Sulfonamindes and Trimethoprim, both inhibit differents steps of folic acid synthesis (humans do not produce folic acid so this does not screw us up)

Question 24

What are some problems with Sulfonamides?

Answer 24

Allergies, kernicterus, and hemolytic anemia

Question 25

What are the three main classes of drugs that inhibit nucleic acid synthesis?

Answer 25

quinolones/fluoroquinolones, furanes, metronidazole.

Question 26

How do quinolones and fluoroquinolones inhibit Nucleic Acid Syntheiss,

Answer 26

Target Topoisomerases

Question 27

What cephalosporins generations are considered the Extended Spectrums? What gram stain bacteria are they active mainly against?

Answer 27

3rd gen - Gram negative

4th Gen- both (cefepime)

Question 28

What are the first gen cephalosporins active against?

Answer 28

Gram pos

Question 29

What are monobactams active against?

Answer 29

aerobic gram neg bacilli

Question 30

What type of bacteria does daptomycin work against?

Answer 30

Gram Pos

Question 31

What are carbepenemes active against?

Answer 31

Basically all pathogens and desistant to destruction by extended spectrum beta lactamases (ESBLs)

Question 32

how do fosfomycins work?

Answer 32

halts muramic acid synthesis

Question 33

Can you use carbepenemes against MRSA?

Answer 33

No

Question 34

Name the classes of antibiotics that inhibit protein synthesis. Which is the only one that is bactericidal?

Answer 34

Aminoglycosides, Oxazolidinones (linezolid), Macrolides, Lincosamides (clindamycin), Phenicols (chloramphenicol), Ansamycins (rifampin)