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Pharm Test 5 > Antibiotics II > Flashcards

Antibiotics II Flashcards

0
Q

MOA of penicillins

A

Bactericidal and time-dependent action.Disrupts cross-linking of the cell wall by irreversible inhibition of transpeptidase.

1) Disinhibition (activation) of autolysins also occurs due to cytosolic accumulation of peptidoglycan precursors; promotes cell wall degradation.
2) Bacterial cell lysis is end result.
3) Most effective against bacteria in the log phase of growth.

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1
Q

Beta lactam Antibiotics class

A

Penicillins

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2
Q

Targets of penicillins known collectively as what

A

Penicillin-binding proteins and include proteins other than transpeptidase

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3
Q

3 Mechanisms of resistance of penicillins

A

1) Inability of lipophilic penicillins to penetrate the G- outer membrane.
2) Acquired mutations in penicillin-binding proteins that lower the binding affinity for the B-lactam.
3) B-Lactamases

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4
Q

Standard,narrow spectrum penicillins (2)

A

Penicillin G, Penicillin V

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5
Q

True/False: PenG and Pen V are active against G-»>G+, also effective against anaerobic bacteria.

A

False: G+»>G-

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6
Q

T/F: Pen G is unstable in stomach acid; pen v is acid-stable and thus orally effective

A

True

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7
Q

penicillinase-resistant, narrow spectrum (anti-staph) prototype

A

nafcillin

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8
Q

T/F: Nafcillin is used only against pen G-resistant staph (MSSA) due to altered PBPs with lower binding affinities

A

True

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9
Q

Aminopenicillins, broad spectrum prototype

A

Amoxicillin, ampicillin

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10
Q

Antipseudomonal, extended-spectrum drugs

A

Ticarcillin, piperacillin

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11
Q

What characterizes amoxicillin?

A

Aditional activity agaisnt G- bacteria due to increased penetration. Susceptible to beta lactamases

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12
Q

Characteristics of ticarcillin and piperacillin

A

Spectrum includes organisms susceptible to aminopenicllins plus Pseudomonas aeruginosa. Given IV for serious hospital acquired G- infections. Susceptible to B-lactamases

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13
Q

Fixed-dose combination with B-lactamase inhibitors:

A

Clavulanic acid-no bactericidal activity of their own; not all B-lactamases are inhibited.

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14
Q

T/F: Penicillins have relatively short half-live (30-90 min) and most are orally well absorbed.

A

False: Not orally well absorbed (diarrhea)

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15
Q

Respiratory preparation of penicillin

A

pen G benzathine

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16
Q

Adverse reactions of penicillins

A

Least toxic Antibiotics.

1) Jarisch-Herxheimer reaction during therapy for syphilis.
2) CNS toxicity (seizures) in pts with high IV doses.
3) Repository prep can be fatal if given IV
4) Amox/Amp can produce rashes not allergy related.
5) Ticarcillin- large IV doses can cause sodium overload

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17
Q

First generation cephalosporin

A

Cefazolin

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18
Q

Activity of cefazolin

A

High activity against G+ MSSA (not MRSA) and strep; less active against G-

19
Q

Second generation Cephalosporin

A

Cefoxitin

20
Q

Activity of cefoxitin:

A

More activity against G- bacteria due to higher affinity for PBPs, greater cell envelope penetration and greater resistance to G- B-lactamases, less active than 1st gen against G+ organisms.

21
Q

3rd generation cephalosporin

A

Ceftriaxone

22
Q

Activity of ceftriaxone

A

Higher activity against G- and good penetration into CNS. Used for treating meningitis and gonorrhea+empiric chlamydia

23
Q

Fourth generation cephalosporin

A

Cefepime

24
Q

Activity of cefepime

A

Highly resistant to B-lactamases and broad antibacterial spectrum; good CNS penetration.

25
Q

Adverse reactions of Cephalosporins

A

Hypersensitivity, Diarrhea, Potentially nephrotoxic

26
Q

Drug selections of cephalosporins

A

3rd generation (ceftriaxone) is most widely used.

27
Q

Carbapenems

A

Imipenem/cilastatin

28
Q

T/F: Imipenem/cilastatin is highly resistant to inactivation by most B-lactamases

A

True

29
Q

Pharmcokinetics of imipenem/cilastatin

A

Given parenterally and eliminated predominantly by the kidneys; imipenem is in fixed-dose combination with cilastatin to prevent renal inactivation.

30
Q

Monobactam

A

Aztreonam- contains a B-lactam ring but it is not fused with a second ring- little cross reactivity for allergies to other B-lactam groups

31
Q

T/F: Aztreonam has a broad spectrum of activity.

A

False: Narrow spectrum- only against G- aerobic bacteria. Highly resistant to B-lactamases

32
Q

Other cell wall synthesis inhibitors besides B-lactams: Prototype glycopeptide

A

Vancomycin

33
Q

MOA of vancomycin

A

Prevents polymerization of cell wall precursors; binds to D-Ala-A-Ala terminus of NAM monomer, blocking addition of NAM-NAG to the NAM-NAG polymer chain (bactericidal).

34
Q

T/F: Vancomycin cannot penetrate G- envelope due to large molecular size; active only against G+ bacteria- S. aureus and S. epidermis

A

True

35
Q

What is the change that caused VRSA?

A

Variations in peptide terminus (D-Ala-D-lactate) producing 1000-fold decrease in binding affinity

36
Q

What is VRSA treated with?

A

Linezolid, daptomycin, or quinupristin/dalfopristin

37
Q

What do you combine Vancomycin with to treat meningitis?

A

3rd gen cephalosporin (ceftriaxone)

38
Q

What drug has the adverse effects of Ototoxic, “red man syndrome”, and Thrombophlebitis with IV infusion?

A

Vancomycin

39
Q

What drug is a bactericidal phosphenolpyruvate analogue that is used in treatment of uncomplicated G- urinary tract infections

A

Fosfomycin

40
Q

Drug that inhibits production of murein monomers in the cytosol by inhibiting the synthesis of UDP-NAM from UDP-NAG covalently binds to the active site (-SH group) of the enzyme enolpyruvate transferase

A

Fosfomycin

41
Q

T/F: Fosfomycin enters the bacterium via a glycerophosphate transporter; mutations to this transporter render the microbe resistant

A

TRUE

42
Q

What drug is a bactericidal cyclic polypeptide isolated from Bacillus subtilus?

A

Bacitracin

43
Q

What drug does this MOA belong to: Inhibits bactoprenol dephosphorylation (bactophrenol is a lipid carrier that transfers murein monomers across the inner membrane to the cell wall)

A

Bacitracin

44
Q

Bacitracin is active against G+/G- bacteria?

A

G+, much less effective against G-. Acquired resistance is unknown

45
Q

Bacitracin is usually available topically in fixed-dosembination with what 2 drugs?

A

Neomycin/polymyxin B

46
Q

T/F: Bacitracin is highly nephrotoxic if administered systemically

A

True

Pharm Test 5 (8 decks)

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