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IAHI Antibiotics > Antibiotic Drugs > Flashcards

Antibiotic Drugs Flashcards

1
Q

Antibiotics: Peptidoglycan synthesis

A
  • Beta Lactams
  • Vancomycin
  • Bacitracin
  • Fosfomycin
  • D cycloserine
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2
Q

Antibiotic: rnap rna synthesis

A
  • rifampin

- fidaxomicin

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3
Q

Antibiotic: Key metabolic reactions

A
  • trimethoprim

- sulfamethoxazole

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4
Q

Antibiotic: Cell membrane

A
  • polymyxins

- daptomycin

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5
Q

Antibiotic: dna replication and repair

A
  • fluoroquinolones

- metronidazoles

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6
Q

Antibiotic: Ribosomes and protein synthesis

A
  • tetracyclines
  • aminoglycosides
  • macrolides
  • oxazolidinones
  • clindamycin
  • chloramphenicol
  • tigecycline
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7
Q

Peptidoglycan biosynthesis

A
  1. Syn MurNAc pentapeptide precursors (cyto)
  2. Lipid linkage; trans disaccharide precursors across membrane
  3. Polymerization catalyzed by PBPs and crosslinking (extracellular)
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8
Q

Beta Lactams

A
  • block peptidoglycan crosslinking via binding PBPs
  • 4 families
    - Penicillin (penicillin, ampicillin, amoxicillin, methicillin, oxacillin, ticarcillin, piperacillin)
    - Cephalosporin (1st gen-cefazolin, cephalexin; 2nd gen-cefuroxime, cefoxitin; 3rd gen-cetriaxone, ceftazadime; 4th gen-cefepime) **4th gen is most broad spectrum
    - Monobactam (aztreonam)
    - Carbapenem (imipenem, meropenem, ertapenem, doripenem)
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9
Q

Mechanisms of Resistance to Beta lactams (3)

A
  • beta lactamASE production=inactivates beta lactam ring
    - encoded in plasmid or chromosome
    - primarily found in Gram NEGATIVE bacteria
  • decreased permeability = prevents beta lactam antibiotics from accessing PBPs
  • altered PBPs = prevent binding of beta lactam antibiotics
    - most common in Gram POSITIVE bacteria
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10
Q

Overcoming Beta lactamase - use inhibitor

A
  • beta lactamase inhibitors: clavulanic acid, sulbactam, tazobactam
  • administer with beta lactam antibiotics
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11
Q

Glycopeptides (vancomycin)

A
  • peptidoglycan inhibitor
  • bind D-Ala-D-Ala at end of peptide side chain in peptidoglycan precursor, thus PBPs can’t act
  • effective on Gram POSITIVE not on gram negative
  • **often used for beta lactam resistant infections (MRSA) or beta lactam hypersensitivity
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12
Q

Cycloserine

A
  • inhibits peptidoglycan crosslinking
  • structure similar to D Alanine
  • **used as second line antiTB therapy
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13
Q

Bacitracin

A
  • in the group that acts at peptidoglycan synthesis
  • too toxic for systemic use; topical ointments (neosporin)
  • binds to pyrophosphate on lipid carrier for peptidoglycan percursors and blocks recycling, thus peptidoglycan syn can’t continue
  • Group A streptococci are 10x more sensitive than other bacteria
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14
Q

Daptomycin

A
  • lipid modified peptide
  • bacteriocidal
  • narrow spectrum, Gram POSITIVE bacteria
  • bind/disrupt cyto memb
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15
Q

Polymyxins

A
  • lipopeptide
  • narrow spectrum, Gram NEGATIVE bacteria
  • adverse effects due to toxicity limits use
  • binds to bacteria LPS in outer membrane
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16
Q

Tetracyclines

A
  • inhibits protein syn; targets 30s function
  • bacteriostatic
  • broad spectrum (overuse thus wide resistance)
  • Resistance mechanisms: efflux pump, mutations of ribosome
17
Q

Tigecyclin

A
  • bacteriostatic
  • binds 30s and additional unique sites on ribosome
  • no cross resistance with tetracyclines
18
Q

Aminoglycosides

A
  • *bacteriocidal (ONLY DRUG that attacks at protein syn)
  • bind 30s and cause misreading
  • USED for hard to kill Gram NEGATIVE bacteria
  • adverse effects = ototoxicity, nephrotoxicity
19
Q

Macrolides (erythromycin, azithromycin, clarithromycin)

A
  • binds 50s unit, prevents elongation of protein
  • bacteriostatic
  • for Gram POSITVE bacteria
  • useful for patients allergic to beta lactams
  • resistance mechanisms (common): modification of rna like methylation; efflux pumps
20
Q

Clindamycin

A
  • bacteriostatic
  • for Gram NEGATIVE
  • useful for community acquired MRSA (resistance to hospital acquired)
  • for tx of infection by toxin prod. S. Aureus
  • resistance mechanisms: methylation; cross resistance with macrolides
21
Q

Chloramphenicol

A
  • bacteriostatic
  • broad spectrum
  • potential toxicity –> aplastic anemia
  • resistance mechanism: add acetyl group to drug
22
Q

Linezolid

A
  • binds 50s
  • used for tx of complicated skin infection
  • NOT effective with Gram NEGATIVE
  • resistance mechanisms: point mutations in ribosomal components to prevent binding; no cross resistance
23
Q

Fluoroquinolones (ciprofloxacin, norfloxacin, moxifloxacin, levofloxacin)

A
  • inhibitors of dna replication
  • bacteriacidal
  • broad spectrum
  • resistance mechanisms: point mutation in bacterial dna prevent antibiotic binding; efflux pump
24
Q

Metronidazole

A
  • inhibit dna replication
  • tx anaerobic bacterial infection
  • common tx for C. Diff.
  • produces radical in anaerobic environment thus damages bacterial dna
25
Q

Rifampin

A
  • bactericidal
  • binds beta subunit of bacterial rna polymerase to inhibit activity thus prevents rna synthesis
  • resistance mechanism: mutation in beta subunit
26
Q

Fidoxomicin

A
  • bactericidal

- noncompetitive inhibitor of rna syn - binds rna polymerase

27
Q

Antimetabolites (sulfonamides, trimethoprim)

A
  • need tetrahydrofolate to make dna; these antibiotics look like substrates in the pathway
  • they are used in combination
  • sulfonamides = metabolic analog of p amino benzoic acid
  • trimethoprim = metabolic analog of dihydrofolate
  • resistance mechanism: acquire another gene encoding dihydrofolate reduction
28
Q

Targets on the bacteria of an antibiotic

A
  • peptidoglycan synthesis
  • RNAP and RNA synthesis
  • key metabolic reactions
  • cell membrane
  • DNA replication and repair
  • ribosomes and protein synthesis

IAHI Antibiotics (1 decks)

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