Lesson 8 - Antimicrobials

Question 1

Chemotherapy

Answer 1

use of drugs to treat diseases

Question 2

Antimicrobials

Answer 2

any drug used in treating infectious diseases

Question 3

Antibiotics

Answer 3

substances produced by some microbes that inhibit or kill other microbes

Question 4

Synthetic drugs

Answer 4

antimicrobial compounds synthesized in the laboratory

Question 5

Selective Toxicity

Answer 5

An ideal in chemotherapy that an antimicrobial drug kills only pathogenic microbes without harming the host.

Historically, reminiscent of the “magic bullet” of Paul Ehrlich.

He used arsenical compound called “Salvarsan”

Question 6

Alexander Fleming

Answer 6

discovered Penicillin extracted from Penicillium mold

Question 7

Gerhard Domagk

Answer 7

discovered sulfanilamides

Question 8

Selman Waksman

Answer 8

discovered Streptomycin

derived from Streptomyces bacteria

Question 9

Howard Florey and Ernst Chain

Answer 9

performed first clinical trials of penicillin extracted from Penicillium chryseogenum

Question 10

How do Penicillins and cephalosporins work?

Answer 10

THey destroy the peptidoglycan layer by disrupting the peptide cross bridges.

Question 11

Cephalosporins

Answer 11

Derived from Cephalosporium acremonium
Beta lactam antibiotic like penicillin
Main ring different from penicillin
2 sites for R groups

Question 12

Polypeptide Antibiotics

Answer 12

Bacitracin
Topical application
Effective against Gram-positives
Blocks transport of NAG and NAM from cytoplasm
Vancomycin
Glycopeptide
Important "last line" against antibiotic resistant 	S. aureus
Hinders peptidoglycan elongation

Question 13

Mycolic Acid Inhibitors

Answer 13

Antimycobacterial antibiotics

Isoniazid (INH)
inhibits mycolic acid synthesis
oral antibiotic

Ethambutol
inhibits incorporation of mycolic acid into cell wall
both are anti-tuberculosis drugs

Question 14

Inhibition of Cell Wall Synthesis

Answer 14

Most common agents prevent cross-linkage of NAM subunits
Beta-lactams are most prominent in this group
Functional groups are beta-lactam rings
Beta-lactams bind to enzymes that cross-link NAM subunits
Bacteria have weakened cell walls and eventually lyse
Affects actively growing cells only

Question 15

Inhibition of Protein Synthesis

Answer 15

Prokaryotic ribosomes are 70S (30S and 50S)
Eukaryotic ribosomes are 80S (40S and 60S)

Drugs can selectively target translation

Mitochondria of animals and humans contain 70S ribosomes
Can be harmful

Question 16

Aminoglycosides

Answer 16

Aminoglycosides 
Broad-spectrum antibiotics
Changes shape of 30S subunit
Treatment of bubonic plague, STD, and 
		Gram-negative infections

Examples: Streptomycin, neomycin, gentamycin

Question 17

Tetracycline

Answer 17

Broad spectrum
Interferes with tRNA attachment
Treatment of intracellular infections
Risk to pregnant women

Question 18

Minimum Inhibitory Concentration

Answer 18

the lowest concentration (in μg/mL) of an antibiotic that inhibits the growth of a given strain of bacteria