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General Pharmacology > PCNs and Cephalosporins > Flashcards

PCNs and Cephalosporins Flashcards

1
Q

What was the first natural antibiotic?

A

penicillin G

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2
Q

The cell envelope of this type of bacteria:

Gram stain: Red/Pink
3 layer envelope

A

Gram (-)

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3
Q

The cell envelope of this type of bacteria:

Gram stain: Blue/Purple
2 layer envelope

A

Gram (+)

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4
Q

What are some common Gram (+) bacteria? (3)

A

Staphylococcus aureus (MRSA, VRSA)

Enterococcus faecalis (VRE)

Clostridium species

Gram (+) bacteria can be found on the skin.

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5
Q

What are some Gram (-) bacteria? (3)

A

Salmonella species

Escherichia coli

Pseudomonas aeruginosa

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6
Q

What type of antibiotic is a “great benefit to medicine and molecular biology”?

A

Natural antibiotics

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7
Q

What beta-lactams are bacteriocidal?

A

All

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8
Q

What are common mechanisms of drug resistance?

A

Mutations in target proteins

Enzymes that inactivate agents (e.g. Beta-lactamases, many others)

Spontaneous changes in membrane permeability

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9
Q

What antibiotics target cell wall synthesis? (4)

A

PCNs

cephalosporins

monobactams

carbapenems

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10
Q

What is the mechanism of action of beta-lactams? (3)

A

bind to penicillin-binding proteins (PBPs)

inhibit transpeptidases

stimulate autolysins which results in cell lysis

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11
Q

What are the mechanisms of beta-lactam resistance? (4)

A
  • b-lactamases
  • reduced pcn binding proteins affinity for b-lactam
  • changes in outer memberane permeability
  • acquired tolerace
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12
Q

Overall, b-lactams are considerably toxic. True or false?

A

False

Low toxicity

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13
Q

What are the adverse reactions to b-lactams? (4)

A

anaphylaxis

hypersensitivity

wheezing

urticaria

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14
Q

How are PCNs excreted?

A

renal tubular cells

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15
Q

Do PCNs enter the CNS?

A

No, except when the meninges is inflamed.

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16
Q

What is the approximate half life of an oral PCN?

A

0.5-1 hour

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17
Q

What are 2 natural penicillins?

A

penicillin G and V

Note: Reduced usage due to widespread resistance.

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18
Q

What is the spectrum of activity for natural PCNs?

A

Gram + only

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19
Q

Natural PCNs such as G, V, and benzathine are still a drug of choice for (5)

A

S. pneumoniae (G)
Syphilis (G-Benz)
N. meningitidis (G)
Minor childhood infections, esp.otitis (V)
Strep throat (G-Benz)

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20
Q

What are 2 semi-synthetic penicillinase resistant drugs?

A

Nafcillin

Dicloxacillin

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21
Q

What category of b-lactam is good for:

Gram + streptococci
Limited due to MRSA
Good CNS penetration w/ meninges inflammation

A

Semi-synthetics: Nafcillin, Docloxacillin

22
Q

What are semi-synthetic, extended spectrum b-lactams?(3)

A

Ampicillin/sulbactam (Unasyn)

  • Amoxicillin/clavulanate (Augmentin)
  • Piperacillin/tazobactam (Zosyn)
23
Q

For semi-synthetic, extended spectrum antibiotics, what is the activity spectrum for:

Gram +

Gram -

A

extended Gram +

some Gram -

24
Q

What are new, synthetic PCN-like b-lactams?

A

Carbapenems

25
Q

What is a type of carbapenem?

A

Imipenem/cilastatin (Primaxin)

26
Q

When and why is Primaxin administered?

A

Used only during superinfections

It is the broadest spectrum b-lactam.

27
Q

Why is cilastatin combined in Primaxin, the synthetic PCN?

A

Inhibits the renal enzyme that immediately degrades the antibiotic.

28
Q

What is a semi-synthetic mono-bactam?

A

Aztreonam (Azactam)

29
Q

What is the activity spectrum of semi-synthetic monobactams?

A

Inhibits PBP’s of Gram(-) only.

Not active against Gram+ strains.

30
Q

What class of b-lactam:

  • Not affected by b-lactamases
  • No b-lactam allergy reaction
  • Gram (-) only
  • Nosocomial (hospital acquired) infections
  • Used in combination with Gram+ agents for extended spectrum
A

monobactam

Drug is aztreonam (Azactam)

Note: Prescribed for pts will allergic reactions with b-lactams.

31
Q

What PCN:

Used in hospital acquired urinary tract and pneumonia
Especially used for pts allergic to PCN
Gram - only

A

monobactams

Aztreonam (Azactam)

32
Q

What PCN:

Not as effective as antibiotics alone
Used in combo with other PCNs
Blocks actions of PCNases

A

semi-synthetics, extended spectum

Unasyn
Augmentin
Zosyn

33
Q

What are characteristics of cephalosporins? (4)

A

Close relative of PCNs (very similar)
Compound is a natural product of molds, like PCNs
Rarely used as a drug of choice
Prophylaxis in surgery

34
Q

Mechanism of action and drug resistance is similar to PCNs. True or false?

A

True

35
Q

Cephalosporin half life is shorter than PCNs. True or false?

A

False, longer than.

36
Q

___% of pts w/ PCN reactions also show

hypersensitivity to cephalosporins.

A

5%

37
Q

3rd generation cephalosporins have good CNS penetration, but it is worse than PCNs. True or false?

A

False, good penetration.

38
Q

What are first generation cephalosporins? (2)

A

Cephazolin (Ancef)

Cephalexin (Keflex)

39
Q

What is the activity spectrum of first generation cephalosporins?

A

Gram+ and SOME Gram-

40
Q

What are the clinical uses of 1st generation cephalosporins (Ancef, Keflex)?

A

Surgical prophylaxis

UTI

ENT infections due to E. coli

41
Q

What are second generation cephalosporins? (2)

A 
Cefuroxime (Zinacef)
        Cefuroxime axitel (Ceftin)
42
Q

What is the activity spectrum of second generation cephalosporins?

A

Gram+ and extended Gram-

43
Q

What are the clinical uses of 2nd generation cephalosporins? (3)

A

H. influenza

E. coli

Surgical prophylaxis

44
Q

What are third generation cephalosporins?

A

Ceftriaxone

Ceftazidime

45
Q

What is the activity spectrum of 3rd generation cephalosporins?

A

Gram +

Extended Gram -

CNS penetration

Long half life

46
Q

What are the clinical uses of 3rd generation cephalosporins?

A

meningitis

sepsis of unknown origin

pneumonias

47
Q

What is a 4th generation cephalosporin?

A

Cefepime (Maxiprime)

48
Q

What is the activity spectrum of a 4th generation cephalosporin?

A

Very broad of both Grams

Aerobic

49
Q

What is the most useful cephalosporin for nosocomial infection that are highly resistant?

A

Cefeprime (Maxiprime)

50
Q

What is the molecular target for b-lactams?

A

cell wall synthesis

General Pharmacology (24 decks)

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