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MBIO 1010 > Antimicrobial Drugs and Drug Resistance > Flashcards

Antimicrobial Drugs and Drug Resistance Flashcards

Lectures 35-36

1
Q

When are antimicrobial drugs used? What are they useful against?

A

Used when immunization has not occurred and the immune system has difficulty to eliminate infection. They are useful against bacterial infection, very few antivirals are available.

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2
Q

True or False: Antimicrobial drugs must display selective toxicity because they’re main task is to control microbes in the host.

A

False: Antimicrobial drug must display selective toxicity because they both kill and control microbes in the host.

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3
Q

What are the two broad categories of antimicrobial drugs?

A

Synthetic and natural antimicrobial drugs

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4
Q

What other ways we can differentiate antimicrobial drugs?

A

If they are bacteriostatic or bacteriocidal

If they are broad spectrum or narrow spectrum

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5
Q

What do cell wall active agents offer in antibiotics?

A

Selective toxicity

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6
Q

What is the largest class of cell wall active agents?

A

Beta-lactam antibiotics

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7
Q

What are the characteristics of beta-lactam antibiotics?

A

Common feature is the beta-lactam ring
Can be modified in the lab to produce semi-synthetic drugs that have a modified spectrum of activity Susceptible to beta-lactamases
Enzyme produced by some bugs to cut and inactivate beta-lactams

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8
Q

Where can beta-lactam antibiotics be found?

A

They can be found naturally occurring: produced by Penicillium and Cephalosporium fungi
Ex) penicillins and cephalosporins

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9
Q

What kind of spectrum of activity does penicillin have?

A

Narrow spectrum

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10
Q

What is penicillin characterized by?

A

A five membered ring attached to the beta-lactam component.

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11
Q

True or False: Penicillin targets transpeptidation in gram positive bacteria and gram negative bacteria.

A

False: Penicillin targets transpeptidation in gram positive bacteria, but cannot penetrate the outer-membrane of gram negative bacteria.

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12
Q

What is some semi-synthetic penicillin modified for? Give an example.

A

It is modified to provide some activity against gram negative bugs
Ex) ampicillin

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13
Q

What cell wall active agent is structurally distinct form penicillin? How does it differ?

A

Cephalosporins- its six membered ring is attached to the beta-lactam component.

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14
Q

True or False: Like penicillin cephalosporin also targets transpeptidation.

A

True

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15
Q

What are the characteristics of cephalosporin?

A

Many semi-synthetic examples
Broader spectrum of activity than penicillin
Better resistance against beta lactamases

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16
Q

What groups are cephalosporin grouped in to?

A

1st generation, 2nd generation etc.

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17
Q

What are structurally similar to growth factors but do not function in the cell?

A

Growth factor analogs

18
Q

What are analogs similar to?

A

Vitamins, amino acids and other compounds.

19
Q

What are example(s) of growth factor analogs?

A

Sulfa Drugs
Ex) sulfanilamide
-Inhibit growth of bacteria by inhibiting folic acid synthesis and thus nucleic acid synthesis
Often used in combination therapy with another analog -> trimethoprim
Combination therapy minimizes the likelihood of resistance
Ex) Isoniazid
-Extremely narrow spectrum cell wall active agent
-Analog of mycolic acid component needed by Mycobacterium spp.

20
Q

What cell wall active agent is a synthetic antimicrobials, inhibits DNA gyrase, and is useful against life-threatening infections? ?

A

Quinolones

21
Q

True or False: Quinolones works against both gram positive and negative bacteria?

A

True

22
Q

What are examples of Quinolones?

A

Ciprofloxacin a fluorinated quinolone (fluoroquinolone)

23
Q

What binds to RNA polymerase preventing transcription?

A

Rifampin

24
Q

What binds to DNA template blocking transcription elongation?

A

Actinomycin

25
Q

What do protein synthesis inhibitors target? Why can this become a problem?

A

Protein synthesis inhibitors target 70S ribosomes. This can be a problem because human cells have 70S ribosomes in the mitochondrial matrix.

26
Q

Which protein synthesis inhibitor binds to the 30S subunit of 70S ribosomes, block translation, and has a narrow spectrum?

A

Aminoglycosides

27
Q

What is aminoglycosides useful against? How else is it used, and when? Give examples.

A

It is useful against gram negative bugs
Often used as a last resort drug
Damaging to the kidneys and ears
Ex) streptomycin, gentamycin and neomycin

28
Q

Which protein synthesis inhibitor is broad spectrum, produced by species of the Streptomyces genus, and binds to the 30S subunit?

A

Tetracycline

29
Q

What is tetracycline made of? How is it used? What are its downsides?

A

Consist of both natural and modified semi-synthetic drugs
Binds to calcium damaging teeth and bone
Shouldn’t be used in children and pregnant women Used in veterinary medicine and to promote animal growth
Creates problems with resistance

30
Q

Which protein synthesis inhibitor has a broad spectrum of activity, and binds to the 50S ribosomal subunit?

A

Macrolides

31
Q

How is macrolide used? What does it inhibit? Give examples.

A

Only inhibits translation of some proteins
Some proteins are preferential translated and others are not
-Creates a detrimental protein imbalance inside of the cell
Useful to treat infection in patients with allergies to beta lactam antibiotics
Ex) erythromycin and azithromycin
Produced by Streptomyces spp.

32
Q

Which protein synthesis inhibitor is produced by Streptomyces spp., a cyclic lipopeptide, and naturally occurring?

A

Daptomycin

33
Q

What is daptomycin active against? How else is it used? When does resistance against this inhibitor occur?

A

Active against Gram-positives
Pathogenic Staphylococcal spp. and Streptococcal spp.
Forms pores in the plasma membrane causing depolarization
Cell cannot synthesize necessary biomolecules
Cell death occurs
Resistance can occur when bacteria alter plasma membrane composition

34
Q

Which protein synthesis inhibitor inhibits fatty acid biosynthesis and is produced by Streptomyces platensis?

A

Platensimycin

35
Q

What kind of spectrum does platensimycin have? What is it used against?

A

Broad spectrum of activity against gram positive bacteria
Useful against important resistant gram positive pathogens
-MRSA and VRE
Does not cause toxicity in the host

36
Q

What is it called when an organism develops a mechanism to elude the activity of an antimicrobial drug that it should otherwise be susceptible to?

A

Antibiotic Resistance

37
Q

What are the two ways genes for antibiotic resistance can be encoded?

A

Genes for antibiotic resistance can either be encoded on a plasmid or directly within the genome.

38
Q

Why is antibiotic resistance so widespread? What areas can this occur in?

A

Resistance is prevalent because of widespread and sometimes incorrect use of antibiotics.
Ex) Medicine, veterinary medicine, agriculture

39
Q

What are the different mechanisms for antibiotic resistance?

A

Reduced Permeability- bacterium looks inside the cell and reduces permeability- just looks through a “window” doesn’t actually leave
Inactivation of Antibiotics
Alteration of target
Development of resistant biochemical pathway
Efflux- lets the “bad guy” in, realizes what’s happening and kicks the “bad guy” out of the cell

40
Q

Give an example of a pattern in antimicrobial resistance.

A

Example: HIV used to be mostly transmitted by sexual intercourse between gay men in Winnipeg. Now, the main transmitter is heterosexual women using injection drug use.

41
Q

What are way(s) to prevent antibiotic resistance?

A

Infection prevention
Rapid and conclusive diagnosis
Appropriate/prudent use of antibiotics
Prevention of transmission

MBIO 1010 (14 decks)

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