November 4 Flashcards

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1
Q

Sulfanilamide

A

1932

First antimicrobial chemical used to treat a wide range of microbes

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2
Q

Streptomyces

A

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

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3
Q

Semisynthetics

A

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

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4
Q

Synthetics

A

Synthesized in a lab

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5
Q

Seletive Toxicity

A

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.

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6
Q

Mechanisms of Antimicrobial Action

A

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

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7
Q

Inhibition of Cell Wall Synthesis

A

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.

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8
Q

How do B-lactams work?

A

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

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9
Q

B-lactamase Sensitivity

A

B-lactamase breaks down b-lactams

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

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10
Q

Vancomycin

A

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

(Cell wall inhibition)

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11
Q

Bactrim

A

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)

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12
Q

Inhibition of Protein Synthesis

A

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

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13
Q

30S Inhibitors

A

Tetracycline

Streptomycin

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14
Q

50S Inhibitors

A

Arthromycin

Chloramphenicol

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15
Q

Narrow Spectrum

A

Treats only a few specific pathogens

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16
Q

Broad Spectrum

A

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

17
Q

Why are broad spectrum antibioitics a problem?

A

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

18
Q

Disruption of the Cytoplasmic membrane

A

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

Examples: Polymixons, Amphotericin

19
Q

Polymixons

A

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

20
Q

Amphotericin B

A

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.

21
Q

Inhibition of Metabolic Pathways

A

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.

22
Q

Antihelmanthic Drugs

A

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

23
Q

Prevention of Viral Attachment

A

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

24
Q

Prokaryotic Ribosome Structure

A

70S

Made up of 30S and 50S

25
Q

Eukaryotic Ribosome Structure

A

80S

Composed of 60S and 40S