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Microbiology > Antimicrobial Treatment (Chapter 10) > Flashcards

Antimicrobial Treatment (Chapter 10) Flashcards

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1
Q

What is the goal of antimicrobial chemotherapy?

A

To administer a drug to an infected person that destroys the infective agent without harming the hosts cells.

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2
Q

What is an antibiotic?

A

Microbial products or their derivatives that kill susceptible microbes or inhibit their growth.

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3
Q

Go through the timeline of when the first chemotherapies and antibiotics were developed.

A

PAUL Ehrlich (1904) - identified trypan dyes that effectively treated African sleeping sickness

Sahachiro HATO (1910) - working with Ehrlich, identified arsenic compounds that effectively treated syphillis

Domagk, Jaques & Therese Trefouel (1935) - discovered sulfonamides and sulfa drugs

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4
Q

Give a timeline of Penicillin

A

FIRST discovered by ERNEST Duchesne (1896)

NEXT Accidentally discovered by Alexander FLEMING

THEN effectiveness demonstrated by FLOREY, CHAIN, HEATLY (1939) - they got the Nobel prize in 1945 for discovery and production of penicillin

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5
Q

What are the characteristics of antimicrobial drugs and the meanings?

A
  • Selective toxicity
    ability of a drug to kill or inhibit pathogen while damaging host as little as possible
  • Therapeutic dose
    drug level required fro clinical treatment
  • Toxic dose
    drug level at which drug becomes too toxic for patient (produces side effects)
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6
Q

What is the Therapeutic Index?

A

The ratio of a drug that is toxic to humans compared to its minimum effective dose:

the smaller the ratio, the more toxic is it

TI = 1.1 is risky

TI-10 is safer

significane: the drug with the highest TI has the widest margin of safety.

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7
Q

What is a narrow- spectrum drug, a broad-spectrum drug and what’s the difference?

A

a narrow spectrum drug only attacks a few different pathogens

a broad spectrum drug attacks many different pathogens

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8
Q

What causes the effects of an antimicrobial drug to vary?

A

concentration, microbe, host

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9
Q

What are the two ways effectiveness is expressed? define them.

A
  • minimal inhibitory concentration (MIC)
    lowest concentration of drug that INHIBITS GROWTH of pathogen
  • minimal lethal concentration (MLC)
    lowest concentration of drug that KILLS pathogens
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10
Q

How do disk diffusion tests work?

A

A disk impregnated with a specific drug are placed on agar plates inoculated with test microbe

the drug DIFFUSES from the disk into the agar, establishing a concentration gradient

clear zones (zones that show inhibition) form around the disks, preventing the growth of that microbe in that region

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11
Q

What are the 3 mechanisms of action for Cell wall synthesis inhibition?

A

Penicillin
Cephalosporins
Carbapenems

Miscellaneous drugs that target the cell wall

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12
Q

What are the mechanisms of action for cell membrane structure or function?

A

Polymyxins

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13
Q

What are the 4 mechanisms of action for protein synthesis inhibition?

A

Amino-gly-co-sides
tetracyclines
Gyl-cyl-cy-clines
Macrolides

Miscellaneous drugs that target the cell wall

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14
Q

What are the mechanisms of action for nucleic acid structure or function inhibition?

A

fluoro-qui-nolones

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15
Q

What are the mechanisms of action for Folic acid metabolism?

A

Sulfonamides

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16
Q

What do the folic acid metabolic antagonists do?

A

block pathways and inhibit metabolism

17
Q

What do the cell wall inhibitors do?

A

Block synthesis and repair

18
Q

What is the significance pf Beta-lactam rings in penicillin and the problems of enzymes that attack it?

A

bacteria can create penicillinase which is a class of enzymes that cuts the b-lactam ring in penicillin

19
Q

Why is it difficult to treat organisms growing in biofilm?

A

They act different than when they are free living.

Antibiotics often cannot penetrate the sticky extracellular material surrounding biofilms

Bacteria in biofilms express a different phenotype and have different antibiotic susceptibility profiles than free living bacteria.

20
Q

What do you use to treat fungal infections?

A

Ampho-tercin B

flu-cytosine

21
Q

What do you use to treat Protozoan disease?

A

Metro-nidazole

22
Q

What do you use to treat helminth disease?

A

Pyrantel

23
Q

How do you treat viral infections?

A

Cant use antimicrobiotics but can be prevented with vaccines.

Tamiflu can shorten the course of the flu.

24
Q

What are the challenges in developing drugs for non-bacterial agents?

A

disrupting viral metabolism requires disruption of cellular metabolism of host

25
Q

What are the 4 factors that influence the efficacy of antimicrobial drugs?

A
  • ability of drug to reach site of infection
  • ability of drug to reach concentrations in body that exceed the MIC of pathogen
  • depend in mode of administration (oral, topical)
  • drugs can be excluded by blood clots or necrotic tissue
  • speed of uptake vs rate of clearance (elimination)
26
Q

What are the 5 mechanisms of drug resistance ?

A

Preventing Inactivate Modification Pump. Alternative

  1. Preventing entry - bacteria can change its permeability and transporters so the drug can’t go through the cellular membrane
  2. Drug Inactivation - Chemical modification of drug by pathogen
  3. Modification of target enzyme of cell structure
    - Can add a functional group of change the metabolism
  4. Pump drug out using efflux pumps
  5. Use of an alternative pathway or increased production of target metabolite.
27
Q

How is drug resistance spread through bacterial populations?

A

Chromosomal genes
R plasmids
Composite transposons

28
Q

What are the new treatment being developed as antimicrobials?

A
  • Teixobactin
  • using bacteriophages as treatment
  • Pre & ProBIOTICS
  • Microbial transplants
29
Q

Most drugs that inhibit protein synthesis or translation block the action of the _____

A

ribosome

30
Q

Sulfonamides interfere with folate metabolism by blocking enzymes required for the synthesis of ______.

A

tetrahydrofolate

31
Q

Antibiotics that affect nucleic acid synthesis specifically affect the processes of replication and ______

A

transcription

32
Q

What are some known was of treating biofilms?

A

DNase, disrupting quarum sensing, daptomycin

33
Q

_____ are particularly challenging to inactivate with antimicrobial chemotherapy because a single metabolic system is responsible for both the microbe and the host cell.

A

Viruses

34
Q

Antibiotics that affect __ and ___ synthesis specifically affect the processes of replication and transcription, respectively.

A

DNA, RNA

35
Q

Identify the three major modes of action of antiviral drugs.

A

Barring virus penetration into host cell
Preventing virus maturation
Blocking virus transcription and translation

Microbiology (13 decks)

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