Cephalosporins 1 Flashcards

1
Q

key features in cephalosporins

A
  • beta lactam ring attatched to 6 member ring
  • aminoadipic side chains
  • dihydothiazine ring
  • acetooxy group off of R 2 (this is leaving group)
  • double bond between C2 and C3 in 6 membered ring
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2
Q
  • goals of cephalosporin structures
A
  • increase spectrum of activity

- improve PK

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3
Q

R1 modifications of cephalosporins associated with…..

A
  • changes in antibacterial activity
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4
Q

R2 modifications of cephalosporin’s associated with…..

A
  • changes in pharmacokinetics and metabolism
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5
Q

mechanism of action of cephalosporins

A
  • inhibit last step of bacterial cell wall synthesis aka transpeptidation
  • block cross linking reaction of peptidoglycans in bacterial cell wall
  • not effective against MRSA or MRE
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6
Q

T or F

Cephalosporin’s are bactericidal

A
  • True
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7
Q

6 P’s of resistance in cephalosporins

A
  • PBPs (alterations in targeted receptor structure)
  • Penetrations (limited drug passage into human cells preventing access to intracellular organisms)
  • Porins (resistance caused by decreased permeability of porin channel mostly gram neg)
  • pathway/process (variation of folic acid
  • penicillinase (bacterial enzymes causing destructionof rug molecule)
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8
Q

cephalosporins have no activity against…..think LAME

A
  • Lysteris
  • Atypicals
  • MRSA
  • Enterococci
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9
Q

1st generation cephalosporins

A
  • cephalexine

- cefazolin

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10
Q

2nd generation cephalosporins

A
  • cefuroxime
  • cefoxitin
  • cefprozil
  • cefotetan
  • loracarbef
  • cafacor
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11
Q

3rd generation cephalosporins

A
  • cefpodoxime
  • ceftriaxone
  • cefixime
  • cefotaxime
  • ceftazidime
  • cefdinir ceftibuten
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12
Q

4th generation cephalosporins

A
  • cefepime
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13
Q

5th generation cephalosporins

A
  • ceftaroline
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14
Q

what generation of cephalosporins is this?

  • potential sub for pen G
  • R1 side chain confers restance to many b-lactamase enzymes
  • not useful for anaerobes such as clostridia or gram neg bacteroides or haemophilus influenza
  • cannot treat meningitis
  • good against gram pos
  • not active against enterococcus
  • some gram neg, but not all bc ring gets cleaved
  • not useful in intracellular infetions bc cannot penetrate human cells such as chlamydia, mycoplasma, legionella, brucella, rickettsia, mycobacteria or francisella
  • active against gram neg proteus mirablis, E,coli, and Klesiella pnuemonia
A

1st generation

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15
Q

Cefazolin 1st gen cephalosporin treats

A
  • S. pneumonia (+)
  • strep pyogenes (+)
  • MSSA (+)
  • Proteus mirabillis (-)
  • e. colo (-)
  • Klebsiella pneumonia (-)
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16
Q

1st gen cepehalosporins indicated for

A
  • good alternative to antistaphylococcal penicillins
  • skin and soft tissue infections
  • surgical prophylaxis
  • reoccurring endocarditits
  • osteomyelitis
  • cannot treat CNS infetions
17
Q
  • have better gram neg activity than gen 1 and slightly less gram pos activity
  • more stable to gram neg beta lactamase
  • some (cefprozil/locarbef) treat influenza and niessieria gonorrhoeae
  • most numerous generation but least utilized in US
A
  • 2nd gen cephalosporins
18
Q
  • members of this subgroup of 2nd gen cephs have methoxy group on beta lactam ring
  • relatively limited activity to gram pos so not as good as true 2nd gen
  • parenteral use only
  • advantage is some anaerobic or faculatative gram neg infections
A
  • cephamycins
19
Q

cefotetan and cefoxitin can be classified as

A

cephamycins

20
Q
  • these antibiotics are chemically incompatible w tetracycline, aminoglycosides and heparin by forming precipitates
A
  • cephamycins (cefotetan and cefoxitin)
21
Q

what makes the cephamycins different and thus more stable against b lactamases of gram neg anaerobes but also diminishes affinity for PBP’s of staph and strem

  • this modificationis what changes spectrum when compared to regular 2nd gen cephs
  • increases activity against gonorrhea
A
  • the methoxy group of C7
22
Q

3 major microrganisms that can be treated w 2nd gen cephs when compared to gen 1

A
  • Neisseria
  • Haemophilis influenza
  • Enterobacter aerogenes
23
Q

2ng gen Cefuroxime coverage according to antibiotic map

A
  • S. pneumonia (+)
  • Strep pyogenes (+)
  • MSSA (+)
  • Proteus mirabilis (-)
  • E. coli (-)
  • Klebsiella pneumonia (-)
  • N meningitides (-)
  • H. influenza (-)
24
Q

cefoxitin/cefotetan antiobiotic map coverage

A
  • S. pnuemoniae (+)
  • strep pyogenes(+)
  • MSSA (+)
  • Proteus mirabilis (-)
  • E. coli (-)
  • Klebsiella pneumonia (-)
  • N meningitides (-)
  • H. influenza (-)
  • bacteriosides fragilis****important
25
Q
  • greater gram neg activity thenprevious gens
  • good strep activity but less staph activity of previous gens
  • broad spectrum
  • strongest association w C. diff
A

3rd gen cephs

26
Q

common structural features in 3rd gen cephs

A
  • R1 is an aminothiazolyl group that increases movement through outter cell membrane, increases PBO affinity and inreases gram neg b lactamase stability
27
Q

3rd gen cephs often used to treat:

A
  • Neisseria gonnoreaha/meningitis
  • haemophilis meningitis
  • proteus
  • UTI E.coli
  • streptococcus pneumonia meningitis
28
Q

3rd gen ceph that treat spirochetes such as Borrelia burgdoferi (lymes disease)

A
  • Cefdinir

- Cefixitime

29
Q
  • 3rd gen targeted for s. pnuemoniae (pneumococcus)
A
  • Cefotaxime

- Ceftriaxone (preffered bc of one dialy dosing)

30
Q

3rd gen that targets gram pos and gram neg anaerobes but NOT c.diff

A
  • ceftizoxime
31
Q
  • some bacteria have rapily inducible b-lactamases and thus should be avoided by 3rd gen cephs or if do use them in combo, what are these bacteria?
    hint pnemonoic: Cephs May Prove Sub Efficacious
A
  • Citrobacter
  • Morganella
  • Providencia
  • Serratia
  • Enterobacter
32
Q
  • special 3rd gen engineered to be active against Pseudomonas by altering aminothiazolyl group with carboxypropyl group
  • however decreases staph PBPs so lacks clinical efficacy of grampus
  • not active on anaerobes or atypicals
A
  • Ceftazidime

- brand name is Avycaz

33
Q

antibiotic map coverage of ceftriaxone/cefotoxime 3rd gens

A
  • S. pnuemoniae (+)
  • strep pyogenes(+)
  • MSSA (+)
  • Proteus mirabilis (-)
  • E. coli (-)
  • Klebsiella pneumonia (-)
  • N meningitides (-)
  • H. influenza (-)
  • Serratia (-)
  • Enterobacter spp (-)
34
Q

antibiotic map coverage of Ceftazidime (keep in mind this is less broad spectrum than regular 3rd gens)

A
  • S. pnuemoniae (+)
  • strep pyogenes(+)
  • Proteus mirabilis (-)
  • E. coli (-)
  • Klebsiella pneumonia (-)
  • N meningitides (-)
  • H. influenza (-)
  • Serratia (-)
  • Enterobacter spp (-)
  • PSUEDOMONAL*** important