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Block 1 > Bacteria and Viruses > Flashcards

Bacteria and Viruses Flashcards

1
Q

mechanisms of resistance by bacteria include:

3 mechanisms

A
  1. inactivation by beta-lactamase (penicillinases)
  2. modification of penicillin binding proteins
  3. impaired penetration to target PBPs
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2
Q

which 2 bacteria resist antibiotics by modifying PBPs

PBP = penicillin binding proteins

A
  1. methicillin-resistant Staphylococcus aureus (MRSA)
  2. penicillin-resistant Streptococcus pneumoniae (PRSP)
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3
Q

mechanism of action for:

cephalosporin

A

D-Ala-D-Ala analogs; bind to PBP and inhibit synthesis of transpeptidase

similar to penicillin

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4
Q

mechanism of resistance for:

cephalosporin

A
  • inactivation by beta-lactamases
  • modification of target PBPs
  • decrease in drug permeability

similar to penicillin

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5
Q

mechanism of action for:

monobactam

A

monocyclic beta-lactam ring

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6
Q

mechanism of action for:

carbapenem

ex: imipenem

A

synthetic beta-lactam drug, structurally related to penicillin

resistant to most beta-lactamases, but susceptible to metallo-beta-lactamase

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7
Q

mechanism of action for:

beta-lactamase inhibitors

A

resemble beta-lactam drugs; inhibit beta-lactamases as a competitive inhibitor

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8
Q

mechanism of action for:

vancomycin

A

binds to D-Ala-D-Ala and causes steric hindrance, inhibiting peptidoglycan synthesis

lacks beta-lactam ring and does NOT bind to PBPs

gold standard of treatment for MRSA; not susceptible to beta-lactamases

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9
Q

mechanism of resistance for:

vancomycin

A

modification of the D-Ala-D-Ala binding site

terminal D-Ala is replaced by D-lactate

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10
Q

Ribosomal antibiotics

6 total

A

30S ribosome:
Aminoglycosides - bactericidal
Tetracyclines (doxycycline)

50S ribosome:
Streptogramins - bactericidal
Erythromycin (Macrolides)
Lincosamides (clindamycin)
Linezolid

buy AT 30, SELL at 50

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11
Q

mechanism of action for:

aminoglycosides

ex: gentamicin, neomycin

A
  • bind to 30S subunit
  • block formation of 70S initiation complex
  • cause mRNA misreading
  • inhibit protein synthesis irreversibly, bactericidal
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12
Q

mechanism of resistance for:

aminoglycosides

ex: gentamicin, neomycin

A

production of drug-inactivating group transferases: aminoglycoside acetyltransferase, adenyltransferase, phosphotransferase

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13
Q

mechanism of action for:

tetracyclines

ex: doxycycline

A
  • bind to 30S subunit
  • inhibit binding of aminoacyl-tRNA to mRNA ribosomal complex
  • bacteriostatic
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14
Q

mechanism of resistance for:

tetracyclines

ex: doxycycline

A
  • efflux of drugs by plasmid-coded efflux protein pump
  • altered permeability to drug
  • enzymatic inactivation of drug
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15
Q

mechanism of action for:

Clindamycin (Lincosamides)

A
  • bind to 50S subunit
  • prevent the ribosome from translocating down mRNA
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16
Q

mechanism of resistance for:

Clindamycin (Lincosamides)

A
  • methylation of ribosomal receptor site
  • production of drug inactivating enzymes
  • reduced permeability to the drug
17
Q

mechanism of action for:

sulfonamides

antifolate drug

A
  • competitive inhibitor of dihydropteroate synthase (DHPS), competes with para-aminobenzoic acid (PABA)

folate synthesis

18
Q

mechanism of resistance for:

sulfonamides

antifolate drug

A
  • decrease in intracellular accumulation
  • increase in production of PABA
  • decrease in sensitivity of DHPS to the drugs
19
Q

mechanism of action for:

trimethoprim

A

selective inhibitor of dihydrofolate reductase (DHFR)

20
Q

mechanism of resistance for:

trimethoprim

A

decrease in sensitivity of dihydrofolate reductase (DHFR) to the drug

21
Q

mechanism of action for:

fluoroquinolones

A
  • inhibit prokaryotic topoisomerase II (DNA gyrase) and topoisomerase IV
  • bactericidal
22
Q

mechanism of resistance for:

fluoroquinolones

A
  • decrease in intracellular accumulation
  • chromosome-encoded mutation in DNA gyrase
  • plasmid-mediated resistance
23
Q

mechanism of resistance for:

macrolides, lincosamides (clindamycin), streptogramins

A

methylation

24
Q

name the DNA viruses

7 total

A

HHAPPPPY:
* Herpes
* Hepadna
* Adeno
* Pox
* Papilloma
* Parvo
* Polyoma

the rest are RNA viruses!

25
Q
A

Block 1 (10 decks)

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