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Pharm Test 3 > Cephalosporins, Carbapenems, and Monobactams > Flashcards

Cephalosporins, Carbapenems, and Monobactams Flashcards

1
Q

Cephalosporin Structure

A

Contain a 6-membered dihydrothiazine ring instead of a 5-membered thiazolidine ring of Penicillin. PROVIDES STABILITY AGAINST MANY B-LACTAMASE ENZYMES THAT RENDER PENICILLINS INACTIVE.

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2
Q

Cephalosporin Mech of Action

A

interfere w/ cell wall synthesis by binding to and inhibiting penicillin binding proteins

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3
Q

Cephalosporins- Bactericidal or Bacteriostatic?

A

Bactericidal, like all B-lactam antibiotics.

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4
Q

Mechanism of Resistance to Cephalosporin Abx

A
  1. Production of B-lactamase enzymes; CEPHALOSPORINS HAVE VARIABLE SUSCEPTIBILITY to B-lactamases
  2. Alterations in PBPs that leadto decreased binding affinity of cephalosporins to PBPs
  3. Inability of abx to reach target due to poor penetration of outer membrane (Gram (-))
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5
Q

Cephalosporin Classification and Spectrum of Activity

A

Divided into 4 major “generations” based on antimicrobial activity and resistance to B-lactamase enzymes.

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6
Q

1st Generation Cephalosporins

A

BEST ACTIVITY OF ALL CEPHALOSPORINS AGAINST GRAM (+) AEROBES. Have limited activity against some Gram (-) aerobes.
Examples:
Cefazolin (Ancef)
Cephalexin (Keflex)

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7
Q

1st Generation Cephalosporins Spectrum of Activity (Cefazolin, Cephalexin)

A 
Gram (+):
MSSA
Pen-susc. S. pneumoniae
Group streptococci
Viridans streptococci

Gram (-): (PEK)
P. mirabilis
E. coli
K. pneumoniae

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8
Q

2nd Generation Cephalosporins

A 
Slightly less active than 1st Gen against Gram (+) aerobes, more active against Gram (-) aerobes and against some anaerobes (cephamycins).
Includes:
cephalosporins- cefuroxime, cefprozil
cephamycins- cefoxitin, cefotetan
carbacephems
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9
Q

2nd Generation Cephalosporins Spectrum of Activity (cephalosporins, cephamycins, carbacephems)

A 
Gram (+): same bacteria as 1st Gen, but with higher MICs
MSSA
Pen-susc. S. pneumoniae
Group streptococci
Viridans streptococci
Gram (-): (HENPEK)
P. mirabilis
E. coli
K. pneumoniae
H. influenzae
Enterobacter spp. (some)
Neisseria spp.

Anaerobes:
cefoxitin
cefotetan
cefmetazole

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10
Q

Important Cephalosporins

A

Cefuroxime

Cefprozil

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11
Q

Important Cephamycins

A

Cefoxitin

Cefotetan

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12
Q

3rd Generation Cephalosporins

A

Less active against Gram (+) aerobes, but have greater activity against Gram (-) aerobes.

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13
Q

3rd Generation Cephalosporins Spectrum of Activity for Gram (+) Aerobes

A

Ceftriaxone & Cefotaxime;
Active against:
PENICILLIN-RESISTANT S. PNEUMONIAE

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14
Q

3rd Generation Cephalosporins Spectrum of Activity for Gram (-) Aerobes

A 
HENKPECKSSS AND MORE
P. mirabilis
E. coli
K. pneumoniae
H. influenzae
Enterobacter spp. (some)
Neisseria spp. (gonorrheae & meningitidis)
Citrobacter sp.
Serratia marcescens
Salmonella sp.
Shigella sp
Pseudomonas aeruginosa- TARGET ORGANISM OF CEFTAZIDIME & CEFOPERAZONE ONLY
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15
Q

4th Generation Cephalosporins

A

Have extended spectrum of activity and excellent stability against B-lactamase hydrolysis- is a POOR INDUCER of B-lactamases in Gram (-) aerobic bacteria.

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16
Q

Important 4th Generation Cephalosporins

A

only CEFEPIME is currently available

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17
Q

Important 3rd Generation Cephalosporins

A

Ceftriaxone- penicillin-resistant S. pneumo
Cefotaxime- penicillin-resistant S. pneumo
Ceftazidim- P. aeruginosa
Cefoperazone- P. aeruginosa

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18
Q

Cephalosporins are NOT active against…

A 
MRSA
ENTEROCOCCUS SP.
Listeria Monocytogenes
Stenotrophomonas maltophilia
C-dif
Atypical bacteria, including Legionella
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19
Q

Cephalosporin Absorption

A

Well-absorbed orally, but have lower [ ]s than parenteral products.

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20
Q

Cephalosporin Distribution

A

NO CSF penetration with 1st & 2nd generation, except CEFUROXIME.
3RD & 4TH GENERATION HAVE GOOD CSF PENETRATION.

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21
Q

Cephalosporin Elimination

A

Most are eliminated by kidneys and require dosage adjustment w/ renal insufficiency.
Exceptions:
CEFTRIAXONE- biliary, also is NOT removed during dialysis like the other cephalosporins
CEFOPERAZONE- liver

22
Q

Cephalosporin Half-Lives

A

Most have relatively short 1/2 lives (< 2 hrs.)
Exceptions:
CEFTRIAXONE (8 HRS.)

23
Q

Important Cephalosporin Clinical Uses 1st Gen.

A

1st Gen: surgical prophylaxis (Cefazolin), MSSA, streptococci

24
Q

Important Cephalosporin Clinical Uses 2nd Gen.

A

2nd Gen: Bacteroides fragilis, polymicrobial infections

25
Q

Important Cephalosporin Clinical Uses 3rd Gen.

A

3rd Gen: meningitis, if PSEUDOMONAS is present or expected, USE CEFTAZIDIME); CEFTRIAXONE IS USED FOR UNCOMPLICATED GONORRHEA, CAP, PRSP, VIRIDANS STREP ENDOCARD

26
Q

Important Cephalosporin Clinical Uses 4th Gen.

A

4th Gen: Pseudomonas

27
Q

Cephalosporin Adverse Effects

A

Hypersensitivity rxns occur most often in pts. w/ history of Penicillin allergy. Cross-reactivity ~5-15%.
Cephalosporins w/ NMTT side chain have unique adverse effects- Hypoprothrombinemia, Disulfiram reaction
G.I- biliary sludging w/ CEFTRIAXONE, pseudomembranous colitis (C-dif diarrhea)

28
Q

Available Carbapenems

A

imipenem
meropenem
ertapenem
doripenem

29
Q

Carbapenem Structure

A

B-lactam ring attached to a 5-membered ring like the penicillins, except w/ a Carbon at position. Also has hydroxyethyl group, results in increased antibacterial activity and greater stability against most B-lactamase enzymes.

30
Q

Carbapenems- Bactericidal or Bacteriostatic?

A

Bactericidal (time-dependent), except against Enterococcus, like other B-lactam antibiotics

31
Q

Carbapenem Mech of Action

A
  • Inhibit cell wall synthesis by binding to/inhibiting PBPs, main target is PBP-2
  • Penetrate very well into bacterial cell walls
  • Bactericidal- Time-dependent
32
Q

Mechanism of Resistance for Carbapenem Abx

A
  • B-lactamase production
  • decreased permeability
  • alteration in PBPs
33
Q

Carbapenem Spectrum of Activity

A
  • the MOST BROAD SPECTRUM agents available

- activity against ANAEROBES, Gram (+) & (-)

34
Q

Carbapenem Spectrum of Activity for Gram (+) Aerobes

A 
- IMIPENEM AND DORIPENEM BEST
MSSA
penicillin-susceptible Strep. pneumo
Groups A, B, and C strep
viridans strep
Enterococcus faecalis only (not E. faecium)
35
Q

Carbapenem Spectrum of Activity for Gram (-) Aerobes

A
  • DORIPENEM AND MEROPENEM BEST
    PSEUDOMONAS AERUGINOSA (not Ertapenem)
    ACTIVITY AGAINST B-LACTAMASE PRODUCING STRAINS THAT OTHERWISE DISPLAY RESISTANCE TO B-LACTAM ABX
36
Q

Carbapenem Spectrum of Activity for Anaerobes

A
  • Have excellent activity against clinically significant Gram (+) and (-) anaerobes
  • BACTEROIDES SPP. (ALL)
37
Q

Carbapenems do NOT have activity against…

A 
MRSA
C-DIF
STENOTROPHOMONAS MALTOPHILIA
ATYPICAL BACTERIAL
coagulase-negative staph
some enterococci
Nocardia
38
Q

Carbapenem Distribution

A

Widely distributed

CSF penetration- imipenem has weak [ ]s, MEROPENEM PENETRATES BETTER than imipenem and ertapenem

39
Q

Carbapenem Elimination

A

All eliminated by kidney & require dosage adjustment w/ renal dysfunction
IMIPENEM is hydrolyzed by DHT enzyme in kidney & can be nephrotoxic. A DHP inhibitor, CILASTIN, is added to drug to protect against kidney damage.

40
Q

Carbapenem Half-Life

A

~1hr, ERTAPENEM= 4 HRS.

41
Q

Carbapenem Clinical Uses

A

Polymicrobial Infections
Nosocomial Infections
Infections due to resistant bacteria, esp. to type 1 or class C B-lactamase enzymes
If P. aeruginosa, NOT ERTAPENEM

42
Q

Carbapenem Adverse Effects

A

Seizures (dose dependent, more likely w/ Ertapenem)

43
Q

Monobactams

A

Aztreonam is the only one available

44
Q

Monobactams Mech of Action

A

Inhibits cell wall synthesis like other B-Lactams by binding to PBPs, esp. PBP-3 of Gram (-) aerobes

45
Q

Monobactams- Bactericidal or Bacteriostatic?

A

Bactericidal- time dependent

46
Q

Mechanism of Resistance to Monobactams Abx

A

Hydrolysis by B-lactamases or decreased permeability

47
Q

Monobactam/Aztreonam Spectrum of Activity

A

ONLY ACTIVITY AGAINST GRAM (-) AEROBES b/c it binds preferentially to PBP-3 of this type of bacteria.
PSEUDOMONAS AERUGINOSA= TARGET ORGANISM

48
Q

Monobactam/Aztreonam Distribution

A
  • only available IV

DOES PENETRATE CSF

49
Q

Monobactam/Aztreonam Elimination

A

Excreted in urine, levels need to be adjusted for renal dysfunction, is removed by hemodialysis

50
Q

Monobactam/Aztreonam Hypersensitivity

A

No cross-reactivity w/ penicillins, can be used in penicillin-allergic patients

Pharm Test 3 (10 decks)

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