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41 Cards in this Set

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Linear strands of the bacterial cell wall are cross-linked by amino acids via this enzyme.
Linear strands of the bacterial cell wall are cross-linked by amino acids via the enzyme TRANSPEPTIDASE.
Linear strands of the bacterial cell wall are cross-linked by this unique set of amino acids.
Linear strands of the bacterial cell wall are cross-lined by the unique set of amino acids, GLYCINE and D-ALANYL-D-ALANINE.
Describe the mechanism of action of beta-lactams.

List the chemical classes of beta-lactam antibiotics.
Beta-lactams act on growing bacteria by binding to and irreversibly inactivating penicillin binding proteins. This blocks transpeptidase from cross-linking the linear strands, making the cell wall very weak.

Beta-lactams also activate autolysins, which degrade the cell wall.

Classes of beta-lactams include penicillins, cephalosporins, carbapenems and monoabactams.
Compare and contrast beta-lactamases of Gm(+) and Gm(-) bacteria.
Gm(+) bacteria have beta-lactamases that are coded by a plasmid are most commonly penicillinases. The B-lactamases can be secreted from Gm(+) bacteria.


Gm(-) bacteria have complex B-lactamases that can be coded for by genetic elements on the chromosome or a plasmid. They are localized to teh periplasmic space of Gm(-) bacteria and can be expressed constitutively or be inducible. The B-lactamases of Gm(-) bacteria are usually broad-spectrum.
MRSA and multi-drug resistant S. pneumoniae (MDRSP) are resistant to the B-lactam antiobiotics because the bacteria:

a) increase the efflux of the drugs
b) enzymatically inactivate the drugs
c) have altered PBPs with very low affinity or no affinity for the drugs.
MRSA and multi-drug resistant S. pneumoniae (MDRSP) are resistant to the B-lactam antiobiotics because the bacteria:

c) have altered PBPs with very low affinity or no affinity for the drugs.
What is the benefit of administering probenecid with Pen G?
Up to 99% of an IM dose of Pen G is eliminated by the kidney and primarily through tubular secretion. Thus, about 75% of a Pen G dose is excreted in 1 hour.

Probenecid prolongs the duration of penicillin in the body by blocking its active transport in the proximal kidney tubule.
What is the benefit of administering repository forms of Pen G?
Repository forms of Pen G (procaine and benzathien salts) are administered IM into a large muscle mass and slowly absorbed from the injection site. This prolongs plasma levels of Pen G.
Penicillin G and penicillin V are classified as:

a) natural penicillins
b) extended specturm penicillins
c) penicillinase-resistant penicillins
Penicillin G and penicillin V are classified as:

a) natural penicillins.
This penicillin is chiefly excreted in the bile.

a) oxacillin
b) ampicillin
c) amoxicillin
d) nafcillin
This penicillin is chiefly excreted in the bile.

d) nafcillin
These 2 penicillins have bulky groups on the beta-lactam ring that decreases their binding to bacterial beta-lactamases.

a) methicillin and oxacillin
b) methicillin and nafcillin
c) oxacillin and cloxacillin
d) nafcillin and cloxacillin
These 2 penicillins have bulky groups on the beta-lactam ring that decreases their binding to bacterial beta-lactamases.

b) methicillin and nafcillin
This penicillin is active against Gm(+) organisms and some strains of E.coli, H.influenzae and Shigella.

a) ampicillin
b) amoxicillin
c) cloxacillin
This penicillin is active against Gm(+) organisms and some strains of E.coli, H.influenzae and Shigella.

a) ampicillin

b) amoxicillin- similar spectrum as ampicillin but not used for shigellosis
c) cloxacillin- used to treat penicillinase-producing staphylococci
Compare and contrast routes of administration and spectrums of amoxicillin and ampicillin.
Amoxicillin and ampicillin are extended spectrum penicillins.

Ampicillin can be given orally, IM or IV. It is active against Gm(+) organisms and some strains of E.coli, H.influenzae, Salmonella, Shigella and Proteus.
Amoxicillin is given orally and is better absorbed than ampicillin. It has a spectrum similar to ampicillin but amoxicillin is not used for shigellosis.
This penicillin is a "ureide" penicillin and is active against both Gm(+) and Gm(-) organisms. Its main advantage is its activity against Pseudomonas and Klebsiella.

a) Carbenicillin
b) Ticarcillin
c) Piperacillin
d) Amoxicillin
This penicillin is a "ureide" penicillin and is active against both Gm(+) and Gm(-) organisms. Its main advantage is its activity against Pseudomonas and Klebsiella.

c) Piperacillin
Identify the one answer choice that contains anti-pseudomonal penicillins.

a) cloxacillin, carbenicillin, ticarcillin
b) amoxicillin, oxacillin, piperacillin
c) carbenicillin, piperacillin, oxacillin
d) carbenicillin, ticarcillin, piperacillin
Anti-pseudomonal penicillins:

d) carbenicillin, ticarcillin, piperacillin
What is the advantage of combining a B-lactamase inhibitor with a penicillin?
B-lactamase inhibitors irreversibly inactivate some B-lactamases and prevent teh inactivation of penicillin drugs. This increases the anti-bacterial spectrum against microorganisms that had previously been resistant due to penicillinase production.
What are the 3 B-lactamase inhibitors discussed in class?
(1) clavulanic acid
(2) sulbactam
(3) tazobactam
B-lactamase inhibitors are combined with penicillins to increase the anti-bacterial spectrum against penicillinase-producing microorganisms that were previously resistant to penicillin treatment.

Name the 4 penicillins for which there are available combinations of penicillin and B-lactamase inhibitors.
(1) amoxicillin + clavulanic acid

(2) ampicillin + sulbactam

(3) piperacillin + tazobactam

(4) ticarcillin + clavulanic acid
Name the 5 penicillinase-resistant penicillins that are only used to treat penicillinase-producing staphylococci.
(1) methicillin
(2) oxacillin
(3) cloxacillin
(4) dicloxacillin
(5) nafcillin
List some adverse effects of penicillins.
--hypersensitivity
--hemolytic anemia
--allergic interstitial nephritis
--impaired platelet aggregation
--electrolyte disturbances
--convulsions
--non-immune mediated rash caused by amoxicillin or ampicillin
Describe hypersensitivity to penicillins.

Which is more common: delayed or immediate?

Which is more serious: delayed or immediate?
Up to 10% of patients taking a penicillin will have a hypersensitivity reaction.

Most often, it is a delayed reaction characterized by maculopapular eruptions, fever, and maybe eosinophilia.

The more serious but less common reaction is the immediate form of hypersensitivity mediated by IgE. Manifestations include early-onset urticaria, laryngeal edema, and anaphylaxis.
Which 2 penicillins are more associated with impaired platelet aggregation and electrolyte disturbances?
1) carbenicillin
2) ticarcillin
Cephalosporins and penicillins inhibit cell wall synthesis in a similar fashion... Describe their mechanism of action.

What is a key difference between cephalosporins and penicillins?
Penicillins and cephalosporins inhibit cell wall synthesis by binding to and irreversibly inactivating several PBPs. this blocks transpeptidase, which is normally responsible for cross-linking linear strands of the cell wall.

Cephalosporins, unlike penicillins, are resistant to Gm(+) penicillinases.

Also the 1st and 2nd generation cephalosporins do not penetrate the BBB even when inflammation is present. Penicillins do not penetrate the BBB well either, but therapeutic concentrations of penicillin can be achieved in the presence of meningeal inflammation.
What are the 1st generation cephalosporins?

How do they differ from the 2nd generation?
1st GENERATION:
--cephalexin
--cefazolin

1st generation cephalosporins (compared to 2nd gen) are:
1) more active vs Gm(+) cocci
2) hydrolyzed faster by Gm(-) B-lactamases
Name the 2nd generation cephalosporins.

Of these, which is more resistant to B-lactamases?
2nd GENERATION:
--cefuroxime
--cefaclor
--cefotetan **more resistant to B-lactamases**
Name the 3rd generation cephalosporins.

How are these different from the 1st and 2nd generation agents?
3rd GENERATION
--cefotaxime
--ceftazidime
--ceftriaxone

The 3rd generation have an expanded Gm(-) spectrum and exhibit some CNS penetration.
Name the 4th generation cephalosporin we need to know.

How is it different form the 3rd generation agents?
4th GENERATION:
--cefepime

Cefepime is comparable to the 3rd gen agents but cefepime has more resistance to B-lactamases.
List the adverse effects associated with cephalosporins.
--hypersensitivity
--renal damage
--interference with vit K metabolism
--disulfuram-like reaction
--pseudocholelithiasis
The cephalosporin methylthiotetrazole side chain is associated with 2 adverse effects. What are they?
1) interference with vitK metabolism, leading to prothrombin deficiency

2) disulfuram-like reaction
Cephalosporins are contraindicated in people that have this type of reaction to penicillin:

a) immediate-type allergic reaction
b) delayed-type allergic reaction
Cephalosporins are contraindicated in people that have this type of reaction to penicillin:

a) immediate-type allergic reaction
What is the purpose of combining imipenem with cilistatin?
Cilistatin does not have antibacterial activity but it prevents the metabolic inactivation of imipenem by dehydropeptidase that is present in the kidney.

Cilistatin increases the percentage of imipenem that is excreted unchanged from 20% to 70%. This is important since imipenem is used to treat nosocomial UTIs.
This agent has the widest spectrum of activity of any B-lactam antibiotic:

a) penicillin
b) ceftriaxone
c) methicillin
d) imipenem
This agent has the widest spectrum of activity of any B-lactam antibiotic:

d) imipenem
Besides imipenem, name the carbapenem agents discussed in class.

How are these two agents different from imipenem?
1) meropenem
2) ertapenem

These 2 agents are similar to imipenem but they are resistant to metabolism by dehydropeptidase.
This monobactam agent is only useful against aerobic Gm(-) bacteria. It is stable to B-lactamase.
AZTREONAM is the monobactam agent that is only useful against aerobic Gm(-) bacteria. It is stable to B-lactamase.
This glycopeptide antibiotic binds to the D-ala-D-ala portion of peptidoglycan precursors and inhibits transglycosylase.
Vancomycin
How do enterococci form resistance to vancomycin?
Resistance in enterococci results from substitution of a D-lactic acid for the terminal D-alanine in the pentapeptide chain. This results in VRE.
How is vancomycin administered?

What are its indications?
Vancomycin is given IV.

It has a narrow spectrum (gram +) and is used to treat MRSA, antibiotic-induced enterocolitis associated with C.diff, streptococcal endocarditis with an aminoglycoside in patients allergic to penicillin and it is active against penicillin-resistant streptococcus.
What are the adverse effects associated with vancomycin?
--rapid infusion may lead to flushing of the upper body, or "Redman or red neck syndrome". Other symptoms include pruritus, hypotension, wheezing and dyspnea.

--nephrotoxicity
--ototoxicity
Identify the agent described by the following:

1) "ureide" penicillin active against Gm(+) and Gm(-) organisms and has increased activity against Pseudomonas

2) extendend spectrum penicillin that is given orally and active against Gm(+) organisms as well as E.coli and Salmonella

3) 1st generation cephalosporin eliminated mainly by glomerular filtration and less so by tubular secretion

4) this carbapenem is formulated with cilistatin and treats nosocomial UTIs

5) cell wall synthesis inhibitor that inhibits transglycosylase and treats MRSA and enterocolitis associated with C.diff

6) these 2 penicillins can impair platelet aggregation and cause electrolyte disturbances
1) "ureide" penicillin active against Gm(+) and Gm(-) organisms and has increased activity against Pseudomonas = piperacillin

2) extendend spectrum penicillin that is given orally and active against Gm(+) organisms as well as E.coli and Salmonella = amoxicillin

3) 1st generation cephalosporin eliminated mainly by glomerular filtration and less so by tubular secretion = cefazolin

4) this carbapenem is formulated with cilistatin and treats nosocomial UTIs = imipenem

5) cell wall synthesis inhibitor that inhibits transglycosylase and treats MRSA and enterocolitis associated with C.diff = vancomycin

6) these 2 penicillins can impair platelet aggregation and cause electrolyte disturbances = carbenicillin and ticarcillin
Carbenicillin, ticarcillin and piperacillin are often combined with an aminoglycoside for treatment of serious:

a) Staph infections
b) TB infections
c) E.coli infection
d) Pseudomonas infections
Carbenicillin, ticarcillin and piperacillin are often combined with an aminoglycoside for treatment of serious:

d) Pseudomonas infections
Identify the correct cephalosporin generation (1st - 4th) that is described by the following:

1) most active against Gm(+) cocci; also active against E.coli and Klebsiella

2) active against Enterobacteriae, Pseudomonas, and N.gonorrhea

3) active against Enterobacteriae, Pseudomonas, N.gonorrhea and has the most resistance to B-lactamases

4) not the most effective against Gm(+) cocci but can treat E. coli, H.influenzae and Bacteroides fragilis
1) most active against Gm(+) cocci; also active against E.coli and Klebsiella = 1ST

2) active against Enterobacteriae, Pseudomonas, and N.gonorrhea = 3RD

3) active against Enterobacteriae, Pseudomonas, N.gonorrhea and has the most resistance to B-lactamases = 4TH

4) not the most effective against Gm(+) cocci but can treat E. coli, H.influenzae and Bacteroides fragilis = 2ND
For each set of adverse effects, identify the correct cell wall synthesis inhibitor (either specific agent or class) with which they are associated:

1) hypersensitivity, vitK metabolism interference, disulfuram-like reaction

2) allergic reactions and seizures with pre-existing neurological abnormality

3) flushing of the upper body

4) impaired platelet aggregation and electrolyte disturbances

5) patient with mononucleosis gets a rash after taking this drug
1) hypersensitivity, vitK metabolism interference, disulfuram-like reaction = CEPHALOSPORINS

2) allergic reactions and seizures with pre-existing neurological abnormality = IMIPENEM

3) flushing of the upper body = VANCOMYCIN

4) impaired platelet aggregation and electrolyte disturbances = CARBENICILLIN, TICARCILLIN

5) patient with mononucleosis gets a rash after taking this drug = AMOXICILLIN, AMPICILLIN