Antimicrobial Drugs CH 10

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BIO 205
updated 4 months ago by elizanudo
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microbiology
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1

Antimicrobial drug

Drugs that treat infectious diseases

2

Antibiotic

Chemical produced naturally by a microbe that inhibits or kills another microbe

3

Synergism

occurs when the effect of two drugs together is greater than the effect of either alone. (sulfa + trimethoprim)

4

Antagonism

occurs when the effect of two drugs together is less than the effect of either alone. (penicillin + tetracycline)

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Superinfection

Can be caused by long term uses of broad spectrum Abx
Ex: C Diff infection

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Spectrum of Activity

Range of activity of a drug against microbes

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Broad spectrum

Effective against a variety of microbes. Long term use may cause “superinfections”

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Narrow spectrum

Effective against EITHER gram positive OR gram negative microbes

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Therapeutic Index

Measurement of drug toxicity. Ratio of toxic dose to the therapeutic dose

Toxic dose = Therapeutic Index

Therapeutic dose

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Selective Toxicity

Antimicrobial agent must be more toxic to pathogen than to host

11

Explain the term “beta lactam antibiotic” and how it is affected by the bacterial enzymes (beta-lactamases).

“Beta Lactam” antimicrobial drugs have a beta lactam ring in the structure (shown in green). Is enzyme produced by bacteria to combat antimicrobial drugs such as penicillin , if the organisms produces beta-lactamase , its going to essentially break down the "garage door (beta-lact.ring) to a house(antibiotic)" so if the organism contains beta-lactamase its going to open up that garage( beta-lac ring) to the antimicrobial drug thus the antibiotic will not work.

12

Explain 2 ways that bacteria can acquire resistance to antimicrobial drugs.

-New mutations of chromosomal genes
-Acquire R-plasmids through recombination

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State 5 mechanisms of drug resistance by microbes

1. Produce enzymes that destroy drug
2. Decrease entry of drug in to cell
3.Pump drug out of cell faster then it can get in
4.Alter target site where the antimicrobial agent actually binds
5.Change metabolic pathway

14

Discuss how people can slow down the rate of antimicrobial resistance that is occurring in today’s society

  • Limit use of antimicrobials
  • High concentrations of drug
  • Use antimicrobial agents in combination
  • Develop new variations of drugs
  • Ban antibiotics in animal feed
15

Refute three common misconceptions about antibiotics

  • “People are (or become) resistant to antibiotics”
  • “Antibiotics cause mutations to make the bacteria resistant”
  • Bacteria that are resistant to antibiotics are stronger and grow faster than sensitive bacteria