L17 Intro to antimicrobial chemotherapy Flashcards

1
Q

Chemotherapy

A

the use of drugs that are selectively toxic to pathogens but innocuous to the host

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2
Q

What to treat syphilis

A

Paul Ehrlich used Salvarsan (arsphenamine)

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3
Q

antibacterials drugs

A
  • aminoglycosides
  • tetracyclines
  • amphenicols
  • penicillins
  • macrolides
  • cephalosporins
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4
Q

Antifungals drugs

A
  • azoles
  • echinocandins
  • polyenes
  • allylamines
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5
Q

Penicillins

A

antibiotics that got their name from the Penicillium mold

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6
Q

cephalosporins on bacterial cell membrane

A

A large group of bactericidal antimicrobials that work via their beta-lactam rings. The beta-lactam rings bind to the penicillin-binding protein and inhibit its normal activity. Unable to synthesize a cell wall, the bacteria die.

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7
Q

Antibacterial drugs that inhibit cell wall synthesis

A

Penicillins and Cephalosporins

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8
Q

Antibacterial drugs that inhibit protein synthesis

A

aminoglycosides
tetracyclines
amphenicols
macrolides

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9
Q

aminoglycosides

A

The aminoglycosides are antimicrobial drugs used alone or in combination with β-lactam antibiotics for the treatment of certain serious aerobic gram (−) infections. Broad spectrum

Inhibit protein synthesis

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10
Q

tetracyclines as an antibacterial

A

Inhibit the 30S ribosomal subunit, hindering the binding of the aminoacyl-tRNA to the acceptor site on the mRNA-ribosome complex. When this process halts, a cell can no longer maintain proper functioning and will be unable to grow or further replicate.

Inhibits protein synthesis

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11
Q

amphenicols

A

Class of antibiotics with a phenylpropanoid structure.

Inhibit bacterial protein synthesis by binding to the 50S ribosomal subunit and affecting the activity of the peptidyltransferase enzyme

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12
Q

macrolides

A

Ability to bind the bacterial 50S ribosomal subunit causing the termination of bacterial protein synthesis.

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13
Q

Antifungal drugs that inhibit cell wall synthesis

A

Echinocandins

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14
Q

Antifungal drugs that alter cell membrane integrity or permeability

A

polyenes
allylamines
azoles

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15
Q

polyenes on fungal membrane

A

antifungal by virtue of binding to ergosterol, which is a prevalent steroid in the fungal cell wall, resulting in depolarization of the membrane leading to increased K+ and Na+ permeability and ultimately cell death.

Alter fungal membrane integritiy

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16
Q

allylamines

A

interfering with the enzymes involved in the manufacture of ergosterol, a crucial component of the fungal cell membrane.

alter fungal membrane integrity and permeability

17
Q

Azoles

A

Work primarily by inhibiting the cytochrome P450-dependent enzyme lanosterol 14-alpha-demethylase.Enzyme is necessary for conversion of lanosterol to ergosterol, vital component of cellular membrane of fungi.

alter fungal membrane integrity and permeability

18
Q

Mechanisms of action of anti-HIV drugs

A

entry inhibitors
* reverse transcriptase inhibitors
* integrase inhibitors
-tegravir
* protease inhibitors
-navir

19
Q

Mode of action of anti-bacterial/fungal drugs

A drug can be -cidal or -static depending on the species

A
  • -cidal - lethal to organism and kills microbes
  • -static - slow down microbial growth by blocking replication
20
Q

Spectrum of action of anti-bacterial/fungal drugs

A
  • broad spectrum - drugs are effective against a wide range of species
  • narrow spectrum - drugs are effective against specific species
21
Q

Minimum inhibitory concentration (MIC)

A

The lowest concentration of a drug required to inhibit the visible growth of a microorganism

22
Q

Minimum bactericidal / fungicidal concentration

A

The lowest concentration of a drug required to kill a microorganism

23
Q

Antimicrobial resistance - a global issue

A

In the top ten health treats
* antimicrobial misuse and overuse (human health, agriculture)
* spread of drug-resistant microbes, e.g., poor infection prevention
* economic cost, e.g., prolonged hospital stays, disability and death

24
Q

Spread of drug resistance

A
  • person → person (by bacteria)
  • bacterium → bacterium (by plasmids)
  • plasmid → plasmid by transposons
    many strains carry multiple resistance genes
25
Q

HIV - mutations and (multi)drug resistance proteins

A
  • reverse transcriptase
  • protease
  • integrase
  • gp41
26
Q

(AST)

A

Antimicrobial susceptibility testing

27
Q

Antimicrobial susceptibility testing

A
  • phenotypic or genotypic identification of microbe(s)
  • susceptibility and resistance of microbe isolates towards drugs
  • 2 standards and interpretation: EUCAST & CLSI
28
Q

phenotypic identification I, II & III

A
  1. Disk Di ffusion
  2. Gradient diffusion (Indicate MIC)
  3. Broth microdilution (Determine MIC)
29
Q

phenotypic identification (I) - disk diffusion

A

collect samples (e.g., body fluids) for culture→
select colonies to prepare a suspension →
inoculate onto an agar plate →
incubation

Zone of inhibition to see how its effectiveness.

30
Q

genotypic identification method

A

PCR

31
Q

Treatment and prevention of antibacterial drugs

A
  • spectrum of action
  • broad spectrum drugs affect both harmful and beneficial species in the GI tract
    ▪ reduce competition between species / increase levels of resistance genes / reduce diversity
  • preoperative prophylaxis - ↓ risks of surgical site infection
  • toxicity
32
Q

Prevention of antifungal drugs

A
  • spectrum of action
  • route of administration, e.g., oral / topical / intravenous
  • toxicity
33
Q

anti-HIV drugs

A
  • combination therapy - single-pill, fixed-dose (e.g., Stribild)
  • potential drug-drug interactions
  • HIV prevention - PrEP (pre-exposure prophylaxis) / PEP (post-exposure prophylaxis)
34
Q

Broad spectrum

A

drugs are effective against a wide range of species

35
Q

Narrow spectrum

A

drugs are effective against specific species

36
Q

Mechanism of drug action

A

The process by which a drug produces a biological effect

37
Q

Big zone of inhibition means

A

More effective drug that inhibits growth of bacteria

38
Q

Antifungal susceptibility testing (AFST) colour detection

A

If alive colour if dead no colour

39
Q

32 well containing strip

A

another antifungal susceptibility test