Antibacterial Agents 1: Introduction

Question 1

Selective Toxicity

Answer 1

Drugs should affect microbe, not host, by taking advantage of biochemical differences

Folate Metabolism, Protein Synthesis, Nucleic Acid Synthesis, Cell Wall, Fungal Cell Membrane

Question 2

Antibiotic resistance

Natural

Answer 2

The bugs just don’t have the drug target (Fungi don’t have peptidoglycan cell walls)

Question 3

Antibiotic Resistance

Escape

Answer 3

Organism escapes consequences because of resource availability, or failure to lyse because of little osmotic pressure difference

Question 4

Antibiotic Resistance

Acquired

Answer 4

Mutational resistance vs. Plasmid mediated resistance

Question 5

Antibiotic Resistance

Acquired

Mutational

Answer 5

Basic chromosomal mutations over several generations

Proper dosing and duration of atbx prevents survival of slight resistance strains

Question 6

Antibiotic Resistance

Acquired

Plasmid Mediated/Genetic Transfer

Answer 6

Resistance conferred by plasmids

Can be a source of multiple drug resistance in a single treatment course

Conjugation, Transduction and transformation

Question 7

Mechanism of Resistance

Altered Targets

Answer 7

Examples:
DNA Gyrase (fluoroquinolones)
Penicillin-Binding Proteins (Beta-lactam antibiotics)

Question 8

Mechanism of Resistance

Enzymatic Destruction

Answer 8

Examples:
B-lactamase (B-lactam atbx)
Acetyltransferase (chloramphenicol)

Question 9

Mechanism of Resistance

Alternative resistant metabolic pathways

Answer 9

Overproduction of PABA or thymidine nucleotides (against sulfonamides)

Question 10

Mechanism of Resistance

Decreased Entry

Answer 10

Normally natural resistance

Against B-lactams, flruoroquinolones, aminoglycosides

Question 11

Mechanism of Resistance

Increased Efflux

Answer 11

Against: Tetracyclines, fluoroquinolones, macrolides

Question 12

Bactericidal Mechanisms

Answer 12

Inhibition of Cell wall
Membrane disruption
DNA function/Synthesis interference

Question 13

Bacteriostatic Mechanisms

Answer 13

Inhibition of protein syntehsis

Inhibition of intermediary metabolic pathways

Question 14

Bactericidal agents are preferred in

Answer 14

Severe infections

Question 15

Bactericidal agents act ______ and their action is often _____

Answer 15

Quickly, irreversible

Question 16

Bactericidal agents can ______ for patients with an impaired host defense

Answer 16

Compensate

Question 17

actericidal agents are required

for treatment of infections in locations that are ________

Answer 17

Not accessible to the host immune response

Question 18

Atbx Absoprtion

Answer 18

Typically Oral or IV, some topical. Oral preferred

Question 19

Atbx Distribution

Readily Enter CSF

Answer 19

Chloramphenicol
Sulfonamides
Cephalosporins (3rd and 4th)
Rifampin

Question 20

Atbx Distribution

Enters CSF with Inflammation

Answer 20

Penicillins
Vancomycin
Ciproflaxocin
Tetracyclin

Question 21

Atbx Distribution

Enters CSF Poorly

Answer 21

Aminoglycosides
Cephalosporins (1st and 2nd)
Erythromycin
Clindamycin

Question 22

Fetal Effects

Answer 22

Drugs that can be taken orally (have the ability to cross the gastric mucosal barrier) can also cross the placenta

Question 23

Post-Antibiotic Effect

Answer 23

Some antibiotics (aminoglycosides and fluoroquinolones) continue to kill/inhibit after the [drug] goes below MIC

Question 24

Antibiotic spectrum

Narrow (Definition)

Answer 24

Most effective on susceptible organism

Question 25

Antibiotic spectrum Narrow (Drugs)

Answer 25

Gram (+) or (-) ``` Aminoglycosides Penicillinase-resistant Penicillins Clindamycin Vancomycin Metronidazole Penicillin G, V ```

Question 26

Antibiotic Spectrum Extended (Drugs)

Answer 26

Gram (+) and (-) Aminopenicillins Cephalosporins Fluoroquinolones (Cip, levo) Carbapenems

Question 27

Antibiotic Spectrum Broad (definition)

Answer 27

Greater scope of activity for initial coverage, more likely to cause superinfections

Question 28

Antibiotic Spectrum Broad (Drugs)

Answer 28

``` Macrolides Chloramphenicol Fluoroquinolones (Moxi, Gemi) Sulfonamides Tetracyclines Trimethoprim ```

Question 29

Cell Wall inhibition | Stage 1 Alanine Racemase:

Answer 29

Cycloserine Enolpyruvate transferase Fosfomycin

Question 30

Cell Wall inhibition | Stage 2 d-ala-d-ala pentapeptide

Answer 30

Vancomycin Bactoprenol lipid carrier Bacitracin

Question 31

Cell Wall inhibition | Stage 3 Transpeptidase

Answer 31

Penicillins Cephalosporins Monobactams Carbapenams

Question 32

Inhibition/Damage to Cell Membrane

Answer 32

Daptomycin, polymixin B

Question 33

Modification of synthesis/metabolism of Nucleic Acids | DNA Gyrase

Answer 33

Fluoroquinolones

Question 34

Modification of synthesis/metabolism of Nucleic Acids | RNA Polymerase

Answer 34

Rifampin

Question 35

Modification of synthesis/metabolism of Nucleic Acids | DNA

Answer 35

Metronidzaole | Nitrofurantoin

Question 36

Inhibition/Modification of protein synthesis | 30S Ribosome

Answer 36

Aminoglycosides | Tetracyclines

Question 37

Inhibition/Modification of protein synthesis | 50S Ribosome

Answer 37

Clindamycin Macrolides Chlorampehnicol Streptogramins

Question 38

Modification of intermediary metabolism | Dihydropteroate SYnthase

Answer 38

Sulfonamides

Question 39

Modification of intermediary metabolism | Dihydrofolate reductase

Answer 39

Trimethoprim