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INF: Infections > Antibiotics > Flashcards

Antibiotics Flashcards

1
Q

Nafcillin

A

Class: (penicillin) beta lactam

Target: penicillin binding proteins (PBPs)

Mechanism: block transpeptidase cross linking of peptidoglycan in cell wall

Spectrum: narrow spectrum, anti-staph

resistant to B lactamase because of bulky R group

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2
Q

Gentamicin

A

Class: aminoglycoside

Target: binds to 30s subunit of bacterial ribosome

Mechanism: irreversible inhhibition of initiation of translation

Spectrum: bactericidal

  • can cause mitochondria side effects
  • can be synergistic with B-lactam abx
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3
Q

beta lactam agents

A

Penicillins:

  • penicllin
  • amoxicillin

Semi-synthetic penicillins (anti-staph)

  • methicillin
  • nafcillin
  • oxacillin

Beta lactam/beta lactamase inhibitor combos

  • amoxicillin/clavulanate
  • piperacillin/tazobactum
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4
Q

Cefazolin

A

Class: (beta lactam) cephalosporin, 1st generation

Target: penicillin binding proteins (PBPs)

Mechanism: inhibit cell wall synthesis

Spectrum: bactericidal; 1st gen used for g+ cocci

-less susceptible to b-lactamase

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5
Q

(fluoro)quinolones action

A
  • inhibit DNA-bound gyrase
  • inhibit replication & transcription of bacterial DNA
  • very selective for bacterial gyrase
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6
Q

Drugs that act on the central dogma (replication/transcription/translation) of biology of bacteria

A
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7
Q

examples of synthetic antimicrobials

A

sulfonamides

isoniazid

quinolones

linezolid

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8
Q

which classes of drugs have activity against pseudomonas aeruginosa?

A

-Beta-lactams (bind PBPs to inhibit cell wall synthesis)

-aminoglycosides (bind 30s subunit of ribosomes, inhibit translation)

-fluroquinolones (bind to & disrupt DNA gyrase, inhibit replication)

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9
Q

RIfamyins (Rifampin)

A

Class: antimycobacterial

Target: inhibit RPOb of RNA polymerase from binding, so that transcription of bacterial DNA is inhibited

Mechanism: inhibit DNA-dependent RNA polymerase, inhibiting transcription

Spectrum: effective for mycobacterium tuberculosis (acid fast bug)

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10
Q

Trimethoprim/sulfamethoxazole

A

Class: sulfonamide

Target: inhibit bacterial dihydrofolate reductase

Mechanism: interferes with folate synthesis

Spectrum: bacteriostatic

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11
Q

Metronidazole

A

Class: nitromidazole

Target: prodrug activated by bacterial enzyme

Mechanism: forms toic free radicals that damage DNA, inhibits DNA replication

Spectrum: bactericidal; only works on anaerobes

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12
Q

Penicillin

A

Class: (prototype) beta lactam

Target: penicillin binding protein

Mechanism: block transpeptidase cross linking of peptidoglycan in cell wall

Spectrum: gram positives

-is a structural analog of D-Ala-D-Ala

*bacteria (liek s. aureus) can produce a B-lactamase enzyme, which cleaves the B-lactam ring of penicillin, making the bacteria resistant

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13
Q

Vancomycin

A

Class: glycopeptide

Target: D-ala D-ala portion of cell wall (earlier step than PBPs)

Mechanism: inhibit cell wall synthesis

Spectrum: bactericidal; only used for gram + bugs

not susceptible to B-lactamase; first glycopeptide abx

-most effective therapy for MRSA infections

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14
Q

translation inhibiting abx (target: ribosomal protein synthesos_ are usually bactericidal or bacteristatic?

A

-static!

(other than amino glycosides)

-ex) tetracyclines, chloramphenicol, lincosamides, macrolides, streptogramins

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15
Q

Piperacillin/tazobactam

A

Class: beta lactam/ B-lactimase inhibitor

Target: penicillin binding proteins (PBPs) & beta lactamase

Mechanism: block transpeptidase cross linking of peptidoglycan in cell wall

Spectrum: extended spectrum

works by inhibiting the beta-lactamase & allowing the beta-lactam part to reach the PBP

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16
Q

Amoxicillin

A

Class: (penicillin) beta lactam

Target: penicillin binding proteins

Mechanism: block transpeptidase cross linking of peptidoglycan in cell wall

Spectrum: gram positives & gram negatives

17
Q

Ceftriaxone

A

Class: (beta lactam) cephalosporin, 3rd generation

Target: penicillin binding proteins (PBPs)

Mechanism: inhibit cell wall synthesis

Spectrum: wider spectrum; used with gram negative infections too

18
Q

Azithromycin

A

Class: macrolide

Target: bind to 50s subunit of ribosome

Mechanism: block translocation (step of translation)

Spectrum:

19
Q

examples of natural antimicrobials

A

(produced during microbial chemical warfare in the environment)

**2/3 of all abx

penicillins

tetracyclines

chloramphenicol

vancomycin

rifamycin

aminoglycosides

macrolides

20
Q

Isoniazid

A

Class: antimycobacterial

Target: targets mycolic acid

Mechanism: inhibits mycoside synthesis

Spectrum: effective for mycobacterium tuberculosis (acid fast bug)

21
Q

Mechanisms of selectivity of translation inhibitors

A
  • selective for prokaryotic ribosomes (70s)– compared to 80s eukoaryotic ribosomes
  • selective accumulation (ex tetracycline inhibits eukaryotic ribosomes just as well as bacterial, but is selectively toxic for bacteria because animal cells don’t accumulate the drug)
  • selective drug activation (prodrug– metronidazole)
22
Q

Levofloxacin

A

Class: fluoroquinolone

Target: DNA- bound gyrase

Mechanism: inhibit DNA-bound gyrase (which inhibits bacterial DNA replication)

Spectrum: bactericidal, broad spectrum

-not to be taken with antacids

23
Q

Methicillin

A
  • semi-snthetic penicillin (B-lactam)
  • mechanism: inhibits cell wall synthesis by binding to penicillin binding protein 2 (PBP2); designed to evade B-lactamse produced by s. aureus

**MRSA= methicillin resistnat staph. aureus: become resistant because they produce an altered PBP2 protein (PBP2a), so that methicillin can’t bind to inhibit cell wall synthesis

24
Q

Augmentin

(Amoxicllin/clavulanate)

A

Class: beta lactam/ beta lactimase inhibitor

Target: penicillin binding proteins (PBPs) and B-lactamase

Mechanism: same as B lactam PLUS protects acainst B-lactamase that destroys B-lactam ring

Spectrum:

  • anti-staphylcoccal med
  • mechanism: B-lactam binds to PBP in cell wall, while B-lactamase inhibitor binds & inhibits B-lactamse, allowing the B-lactam abx to function
25
Q

bactericidal antibiotics

A
  • peptidoglycan synthesis inhibitors
  • DNA disruptors
  • aminoglycosides
  • polymyxins, lipopeptides
26
Q

Translation Inhibitor Antibiotics

A

BIND TO 30S SUBUNIT OF RIBOSOME:

-Aminoglycosides (ex streptomycin)- most lethal; tetracyclines; spectinomycin; neomycin

BIND TO 50S SUBUNIT OR RIBOSOME:

-chloramphenicol & clindamycin

BLOCK EXIT TUNNEL:

-macrolides

BLOCK PEPTIDYL TRANSFER/TRANSLOCATION:

-oxazolidinones (ex linezolid)

27
Q

Imipenem-cilastatin

A

Class: carbapenem

Target: penicillin binding proteins (PBPs)

Mechanism: inhibit cell wall synthesis

Spectrum: broad spectrum

-resistant to B lactamase; cilastatin is to reduce inhibition of drug by kidney

28
Q

Doxycycline

A

Class: tetracycline

Target: bind to 30s subunit of ribosome

Mechanism: prevent attachment of aa-tRNA to A site; preventing translation

Spectrum: bactericidal

29
Q

Cephalosporins

A
  • B-lactam antibiotics, structurally related to penicillin
  • mechanism: irrecersibly inactive the transpeptidase that crosslinks the peptidoglycan in the cell wall of the bacteria

INF: Infections (5 decks)

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