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Microm 442 > Lecture 7 Antimicrobials > Flashcards

Lecture 7 Antimicrobials Flashcards

1
Q

What are the key biological processes of bacteria?

A
  • Cell wall
  • Cell membrane
  • DNA replication
  • Transcription
  • Protein synthesis
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2
Q

What are some sources of antimicrobials?

A
  • Natural (Penicillin)
  • Semi-synthetic
  • synthetic
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3
Q

What are some things to consider on drug choice?

A
  • absorption
  • Tissue distribution
  • Metabolism/excretion
  • Time-dependent killing
  • concentration-dependent killing
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4
Q

Bactericidal vs bacteriostatic .

A

Death versus inhibit growth- use cidal when immunocompromised or using prosthetics.

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5
Q

MIC, MBC

A

minimum inhibitory concentration, minimum bactericidal concentration

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6
Q

When would you want to to give combination therapy?

A 
• Empiric therapy
• Prevent resistance
• Enhanced efficacy 
- Synergy
- Additive
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7
Q

What are some susceptibility tests?

A
  • Broth Dilution

- Diffusion tests (Kirby-bauer disc diffusion, ETEST)

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8
Q

Which antibiotics attack cell walls?

A
  • β-lactams (penicillins and cephalosporins)

- Glycopeptides (vancomycin)

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9
Q

What are abx for cell membrane?

A
  • Polymyxins
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10
Q

What abx is used for DNA synthesis?

A
  • [Fluro]quinolones (e.g. ciprofloxacin)
  • Sulfonamides and trimethoprim (e.g. Bactrim)
  • Metronidazole
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11
Q

What abx attacks transcription?

A
  • Rifampin
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12
Q

Which abx attacks protein synthesis?

A
  • Aminoglycosides (e.g. gentamycin)
  • Macrolides (e.g. azithromycin, “Z-pack”)
  • Tetracyclines
  • Lincosamides (e.g. clindamycin)
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13
Q

Which abx are 30s inhibitors?

A
  • aminoglycosides
  • tetracyclines
  • glycineglycine
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14
Q

What are some 50s inhibitors

A
  • erythromycin
  • clindamycin
  • chloraphenocol
  • oxazolidonone
  • streptogramine
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15
Q

Why care about resistant mechs?

A

helps in:

  • susceptibility testing
  • predict resistance without testing
  • predict MIC
  • Risk of infection control
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16
Q

What are some mechs of resistant?

A
  • efflux
  • restricting enzymes
  • target modification
  • Restrict access to target
17
Q

How is resistance expressed?

A
  • intrinsic (chromosomal)
  • De Novo mutations
  • acquired
18
Q

What are the biggest concern for infection control

A
  • constitutive

- inducible

19
Q

What are some intrinsic resistance?

A
  • Impermeability

- biofilms

20
Q

What is Target site mutation

A

A mutation of the actual site can occur, inhibiting a abx,

e.g. mutations in topoisomerase confer fluoroquinolone resistance

21
Q

What is target site protection?

A

Blocks target site from abx

e.g. methylation of 16S rRNA alters binding of erythromycin to ribosome

22
Q

How does inactivation by hydrolysis help pathogens resist?

A

e.g. β-lactamase inactivation of β- lactams by hydrolysis of drug

23
Q

What is inactivation by steric hinderance?

A
  • Modify abx

e. g. aminoglycoside- modifying enzymes

24
Q

What is the problem with efflux pump resistance?

A
  • Can be broad or narrow spectrum

- Up regulation of pumps can lead to multi-drug resistance (tetracylcines, macrolides etc)

25
Q

How can you end up with multi drug resistance?

A
  • encode multiple genes
  • Encode gene that can target multiple abx
  • selective pressure
26
Q

What are some hints in drug names?

A
  • cef… = cephalosporin
  • …cillin = penicillin
  • …cillin/… = beta-lactam/beta-lactamase inhibitor
  • …floxacin = fluroquinolone
  • …cycline = tetraclycine
  • …mycin does not indicate drug class
27
Q

What are some Beta-Lactams?

A 
(most are broad)
• Penicillins
• Cephalosporins 
• Monobactams 
• Carbapenems (most effective)
28
Q

How do Beta-lactams work?

A

Bind to penicillin binding protein, disrupts peptidoglycan and prevents crosslinks form occurring. Inhibits cell growth

29
Q

What are some adverse affects of Beta-lactams?

A
  • Allergies mild to anaphylaxis
  • Diarrhea
  • Stevens-Johnson syndrome
  • Interstitial nephritis
  • Neutropenia and thrombocytopenia
  • Clostridium difficile infection/overgrowth • Seizures
30
Q

What is a relatively broad spectrum penicillin?

A

Ampicillin, Penicillin G/V

31
Q

What is a narrow spectrum penicillin?

A

Nafcillin

32
Q

What is a broad spectrum penicillin combo that is good for resistant strains?

A

Piperacillin/tazobactam (Zosyn)

33
Q

What are the subclasses for cephalosporins?

A

Gen 1-5 (5 is best) . Going down to 5, goes from good with g+ to good with G+ and -. 5th is best for resistance.

34
Q

What do cephalosporins do not work on what organism?

A

Cephalosporins don’t treat Enterococcus!

35
Q

What are three general mechs to resist Beta-lactams?

A
  • decreased penetration (barrier)
  • inactivation of abx by enzyme
  • Alteration of target site
36
Q

What type of resistance is resistant to all beta-lactamses?

A

AmpC Beta- lactamases, Enterobacters biggest problem.

Microm 442 (16 decks)

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