November 4

Question 1

Sulfanilamide

Answer 1

1932

First antimicrobial chemical used to treat a wide range of microbes

Question 2

Streptomyces

Answer 2

More than 1/2 of antibiotics are derived from Streptomyces bacterium in soil, usually semisynthetics

Question 3

Semisynthetics

Answer 3

Altering naturally produced antibiotics in a lab to make them more readily absorbed, more resistant to low pH

Question 4

Synthetics

Answer 4

Synthesized in a lab

Question 5

Seletive Toxicity

Answer 5

You want the drug to be more toxic to the pathogen than to the host, so you target diffrences between the host and pathogen (cell walls). There are more antibacterial drugs than anything else (largest in number and diversity), there are fewer drugs to treat eukaryotic infections (antiprotozoal drugs, antifungals), the fewest number and diversity is in antiviral drugs, viruses use a lot of the host cell’s enzymes to metabolize and replicate making it difficult to selectively target viruses.

Question 6

Mechanisms of Antimicrobial Action

Answer 6

1) Inhibition of cell wall synthesis
2) Inhibition of protein synthesis
3) Disuption of cytoplasmic membrane
4) Inhibition of Metabolic Pathways
5) Prevention of Viral Attachment

Question 7

Inhibition of Cell Wall Synthesis

Answer 7

Damages the cell wall, leaving the cell with no protection from osmotic pressure, the cell will lyse.

This is a good target, human cells lack cell walls

Many act on growing cells (log stage), peptidoglycan is actively growing.

Question 8

How do B-lactams work?

Answer 8

Prevent the formation of amino acid crossbridges between NAM units, they do not affect peptidoglycan that has already been made. Many drugs are semisynthetic derivatives of b-lactams (more stable in acidic environments, more readily absorbed, more active against more types of bacteria).

The simplest b-lactams are only effective against aerobic Gram-negative bacteria.

Examples: Cephalosporins and Penicillin

Question 9

B-lactamase Sensitivity

Answer 9

B-lactamase breaks down b-lactams

Many microbes naturally produce b-lactamase, but there are some semisynthetics that can inhibit B-lactamase.

Question 10

Vancomycin

Answer 10

Interferes with specific alanine-alanine crossbridges in many Gram-positive bacteria

(Cell wall inhibition)

Question 11

Bactrim

Answer 11

Blocks secretion of NAG and NAM from the cytoplasm, selectively toxic because it has no effect on animal cells (no cell wall) or plant cells (no peptidoglycan)

(cell wall synthesis inhibition)

Question 12

Inhibition of Protein Synthesis

Answer 12

Proteins: enzymes, structural, regulation, pumps, channels-transport across membranes

Selectively toxic: Prokaryotic ribosomes are 70S, composed of 30S subunit and 50S subunits, but Eukaryotic ribosomes are 80S and composed of 60S and 40S subunits.

Mitochondial and chloroplast ribosomes however, are 70S, made of 30S and 50S

Single subunits can be targeted

Question 13

30S Inhibitors

Answer 13

Tetracycline

Streptomycin

Question 14

50S Inhibitors

Answer 14

Arthromycin

Chloramphenicol

Question 15

Narrow Spectrum

Answer 15

Treats only a few specific pathogens

Question 16

Broad Spectrum

Answer 16

Treats a variety of pathogens, this can be problematic you can kill the host’s natural microflora, such as in the gut and vagina.

Question 17

Why are broad spectrum antibioitics a problem?

Answer 17

They can kill the host’s natural microflora causing secondary infections such as: Clostridium difficile causes psuedomembranous colitis (C. diff), Candida albicans causes yeast infections

Question 18

Disruption of the Cytoplasmic membrane

Answer 18

Many drugs become incorporated into the membrane and damage its integrity, usually by forming pores.

Examples: Polymixons, Amphotericin

Question 19

Polymixons

Answer 19

Disrupts the cell membrane of some Gram-negative bacteria, but it is highly toxic to human kidneys

Question 20

Amphotericin B

Answer 20

Targets ergosterol in the cell membrane of fungi (ergosterol is similar to cholesterol), it forms pores in the cell membrane. Humans can be somewhat susceptible , there are a lot of toxicity issues with oral antifungals–the liver and kidneys must be carefully monitored.

Question 21

Inhibition of Metabolic Pathways

Answer 21

Must be careful to NOT shutdown the host

Antimetabolic agents are commonly heavy metals such as arsenic. Some arsenic drugs treats sleeping sickness caused by a protozoan.

Question 22

Antihelmanthic Drugs

Answer 22

Used in the treatment of parasitic worms that stay in place by swimming in the intestines. These drugs paralyze the worm and it exits in the feces.

Example: Human Round Worm, *Ascans lumbricoides *

Praziquantal

Question 23

Prevention of Viral Attachment

Answer 23

To invade the host cell, viruses must attach to the host cell via chemical attachment

Attachment proteins on viruses and complementary receptor protein on host cell

Attachment antagonists–peptide and sugar analogs of proteins

Question 24

Prokaryotic Ribosome Structure

Answer 24

70S

Made up of 30S and 50S

Question 25

Eukaryotic Ribosome Structure

Answer 25

80S

Composed of 60S and 40S