Cephalosporins Flashcards

1
Q

What kind of antibiotics are cephalosporins?

A

Semisynthetic beta lactam antibiotics. Their beta lactam ring connected to a 6 membered ring allows greater stability against B-lactamase enzymes.

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2
Q

Cephalosporins Mechanism of Action

A

Bind PBPs to inhibit the final transpeptidation step of peptidoglycan cell wall synthesis

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3
Q

Cephalosporins

Cidal or Static?

A

Bactericidal

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4
Q

Which generation of cephalosporins is most stable against beta-lactamase enzymes?

A

4th Gen

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5
Q

Cephalosporins

Mechanisms of Resistance

A
  • Production of Beta-lactamase enzyme
  • Alteration in PBPs
  • Alter outer membrane to decrease permeability
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6
Q

Cephalosporins Elimination

A

Primarily by kidneys, except for ceftriaxone (biliary) and cefoperazone (liver)

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7
Q

Cephalosporins Elimination Half Life

A

Most are about 2 hrs, but ceftriaxone is longer at 8 hrs

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8
Q

First Gen Cephalosporins

Spectrum of Activity

A

Best against Gram Positive aerobes
MSSA, PSSP
Group and viridians strep

Gram negative aerobes (PEK)
Proteus mirabilis
E coli
Klebsiella

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9
Q

2nd Gen Cephalosporins

Spectrum of Activity

A

Less active against Gram Positive aerobes
MSSA, PSSP, group and viridians strep

More active against Gram Negative aerobes (HENPEK)
Haemophilus
E coli
Neisseria
Proteus
Enterobacter
Klebsiella
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10
Q

Subgroup of 2nd Gen Cephalosporins has special activity against what bacteria?

A

Cephamycins have activity against anaerobes (like Bacteroides)

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11
Q

3rd Gen Cephalosporins

Spectrum of Activity

A
Much better against Gram Negative aerobes (HENPECKSSS +P)
Haemophilus
E coli
Neisseria
Proteus
Enterobacter
Citrobacter
Klebsiella
Serratia
Shigella
Salmonella
Pseudomonas (only ceftazidime)
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12
Q

4th Gen Cephalosporins

Spectrum of Activity

A

Stable against B-lactamases. Gram positive activity similar to ceftriaxone.
Gram Negatives - Pseudomonas aeruginosa, B-lactamase producing Enterobacter spp.

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13
Q

5th Gen Cephalosporins

Spectrum of Activity

A

Respiratory pathogens: Haemophilus influenzae, Strep pneumoniae, Moraxella, Staph aureus

SSSI: Strep pneumoniae, MRSA

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14
Q

Cephalosporins Absorption

A

Oral is well absorbed, but achieves lower serum concentration than parenteral

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15
Q

Cephalosporins

Distribution

A

Widely distributed to tissues and fluids.

Good CSF penetration with 3rd and 4th gen cephalosporins

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16
Q

Cephalosporins Adverse Effects

Hypersensitivity

A

Present in 5% of pts

5-15% cross reactivity with penicillin allergy

17
Q

Cephalosporins Adverse Effects

MTT Side Chain

A

Cephalosporins with an MTT side chain can cause hypoprothrombinemia and alcohol intolerance.