Beta Lactam Antibiotics and Other Cell wall and membrane-Active Antibiotics

Question 1

The primary mechanism of bacterial action of amoxicillin

Answer 1

Inhibition of peptidoglycan cross linking

Question 2

The _______antibitoics also activate autolysins

Answer 2

Beta lactams

Question 3

Synthesis of N-acetylmuramic acid is inhibited by

Answer 3

fosfomycin

Question 4

Inhibits transglycoase, preventing elongation of peptidoglycan

Answer 4

Vancomycin

Question 5

Most appropriate teatment for gonorrhea

Answer 5

Single intramuscular dose of ceftriaxone

• Alernative drugs
  
  • cefixime
  • azithromycin
  • spectinomycin

Question 6

Treatment for primary syphilis

Answer 6

IM Benzathine penicillin G 2.4 million units

• For penicillin allergic patients
  
  • ora; doxycycline or tetracycline for 15 days
• Single dose of cefriaxone may cure incubating syphilis

Question 7

Ceftriaxone and nafcillin are bothe eliminated via _______

Answer 7

bile

Question 8

_____ and ____ cephalosporins are not effective for meningitis because they do not readily cross the BBB

Answer 8

First and Second

Question 9

3rd generation cephalosporins cross the BBB except __________ and __________

Answer 9

cefoperazone and cefixime

Question 10

Renal elimination of pencicillin is inhibited by ______

Answer 10

Probenecid

Question 11

Penicillin and ________ have no cross reactivity

Answer 11

Aztreonam

Question 12

Pneumococcal isolates with a minimal inhibitory concentration for penicillin G of greater then ________ are highly resistant

Answer 12

2 mcg/ml

Question 13

Most appropriate treatment for Pneumococcal meningitis resistant to penicillin G

Answer 13

Ceftriaxone splus vancomycin

Question 14

Resistance of pneumococci to penicillin G is due to _________

Answer 14

Changes in chemical structure of target penicillin binding proteins

Question 15

Treatment of choice if the CSF smear revealed Gram positive rods resembling diphtheroids

Answer 15

Ampicillin

Question 16

A patient needs antibiotic treatment for native valve, culture positive infective enterococcal endocarditis. His medical history includes a severe anaphylactic reaction to penicillin G during the last year,

Answer 16

Vancomycin

Question 17

_____is abacterical glycoprotein. Not absorbed afrer oral adminsitration. Effective againts MRSA

Answer 17

Vancomycin

Question 18

Narrow spectum Penicillins

(Penase-susceptible)

• Pen G
• Pen V

Answer 18

Used in streptococcal and meningococcal infections. DOC for syphilis

Rapid renal elimination; short half-lives necessitate frequent dosing. SOme bilairy clearance of nafcillin and oxacillin

SE: hypersensitivity reactions. Assume compelte cross-reactivity; GI distress and maculopapular rash (ampicillin)

Question 19

Penase resistance Penicillins

Answer 19

Nafcillin and Oxacillin

Question 20

Wider spectrum (+/-) Penicillinase inhibitor Penicillins

(Ampicillin, Amoxicillin, Piperacillin, Ticarcillin)

Answer 20

Greater activity vs gram-negative bacteria

All penicilin( and cephalosporins) are bactericidal

Use with clavulanic acid/tazobactam

Question 21

First generation Cephalosporin

(Cephalexin)

Answer 21

Inhibits transpeptidation

Used in ski, soft tissue UT infections\

Oral use for older drugs. Mostly IV for newer drugs. Renal elimination

SE: hypersensitivity reactions. Assume complete cross-reactivity between cephalosporins. Partial with penicillins, GI distress

Question 22

Second generation cephalosporins

(Cefaclor, cefotetan, Cefprozil, cefoxitin, cefuroxime)

Answer 22

Inhibit transpeptidation

More active vs S. pneumoniae and H. influenzae; B fragilis (cefotetan)

Short half lives

SE: hypersensitivity reactions. Assume complete cross-reactivity between cephalosporins. Partial with penicillins, GI distress

Question 23

3rd generation cephalosporins

(Cefriaxone, cefotaxime, ceftazidime, cefixime, cefpodoxime proxetil, cefdinir, cefditoren pivoxil, ceftibuten)

Answer 23

Inhibit transpeptidation

Many uses including pneumonia, meningitis, and gonorrhea

3rd generation drugs enter the CNS

Question 24

4th generation cephalosporin

(Cefepime)

Answer 24

Borad activity

Beta lactamase-stable

Question 25

Carpapenems

(Imipenem-cilastatin, Doripenem, meropenem, ertapenem)

Answer 25

Broad spectum includes some PRSP strains (not MRSA), gram negative rods and pseudomonas spp

Parenteral;cilastatin inhibits renal metabolism of imipenem (dehydropeptidase I)

Partial cross-reactivity with pencillins, CNS effects includes confusion and seizures

Question 26

Monobactams

(Aztreonam)

Answer 26

Active only vs gram negative bacteria: klebsiella, Pseudomonas, and Seratia spp

Parenteral use. renal elimination

GI upsets, headache, vertigo. no cross-allergenicity with beta lactams

Question 27

Glycopeptides

(Vancomycin, teicoplanin, dalbavancin, oritavancin, televancin)

Answer 27

Gram positive activity include MRSA and PRSP strains.

Parenteral (Oral for C. difficile colitis). Renal elimination IV olny, long half-life; Teicoplanin long half life (45-70h) permits once dosing; Televancin: IV, once daily dosing; Dalbavancin: IV very long half-life (>10 days) permits once-weekly dosing; Oritavancin: IV, very long half-life (>10 days) permits once weekly dosing

RED MAN SYNDROME

Question 28

Lipopeptide

(Daptomycin)

Answer 28

Destabilizes membrane (causes potassium leak and cell death)

Gram positive activity; used in endocarditis and sepsis

Renal elimination

Myopathy. monitor CPK weekly

Question 29

Antimetabolite that blocks the incorporatioin od D-Ala into the pentapeptide chain

Answer 29

Cycloserine

Neurotoxic

Question 30

Peptide antibiotic that intereferes with a late stage in cell wall synthesis in Gram positive organisms.

Limited to topical use

Answer 30

Bacitracin

Question 31

_____ causes interstitial nephritis

Answer 31

Methicilin

Question 32

______ implicated in pseudomembranous colitis

Answer 32

Ampicillin

Question 33

_______ associated with neutropenia

Answer 33

Nafcillin

Question 34

Cephalosporin that is excreted via bile

Answer 34

Cefoperazone and Ceftriaxone