Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Foundations of Medicine Week 3 > Cell Wall Inhibitor Lecture Sep 12 > Flashcards

Cell Wall Inhibitor Lecture Sep 12 Flashcards

1
Q

What are the 4 types of beta lactam ABx?

A

penicillins

cephalosporins

carbapenems

aztreonam

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How do all beta lactam abx work?

A

they bind to the penicillin binding proteins, which are transpeptidases that catalyze the terminal reactions in bacterial cell wall synthesis

this blocks cell wall synthesis and causes a build-up of cell wall precursors which leads to the activation of autolytic enzymes

the cells lyse

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Specifically what site do beta lactams bind?

A

they bind the d-alanyl-d-alanine substrate site ON the transpeptidase, so the dipeptide on the other sugar can’t enter the binding site and undergo the transpeptidase reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Are beta lactams bacteriostatic or bacteriocidal?

A

bacteriocidal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Would swelling be more likely to occur when the cell is in a hypotonic or hypertonic solution?

A

A hypotonic because the water will want to flow where there are more ions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are penicillins active againse?

A

gram positive organisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What drug is given in tandem with penicillins to reduce the renal secretion of the penicillin?

A

probenecid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the side effects of penicillins?

A

seizures, nausea, and diarrhea

Hypersensitivity reactions are very common-mild rash to anaphylaxis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the antistaphylococcal penicillins?

aka Penicillinase-resistance penicillins?

A

Nafcillin

Dicloxacillin

(methicillin no longer used)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are nafcillin and dicloxacillin reserved for?

A

Methicillin Sensitive Staphylococci aureus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What three drugs are used as penicillinase inhibitors?

A

clavulanate (combined with penicillin and amoxicillin)

Sulbactam Icombined with ampicillin)

Tazobactam (combined with piperacillin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Why is penicillin ineffective against gram negative bacteria?

A

It is unable to penetrate across the outer membrane of gram negative bacteria.

THe LPS blocks access and the penicillin can’t pass through the porins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What class of penicillins are able to cross the membranes of gram negative bacteria?

A

Aminopenicillins

AMPICILLIN

AMOXICILLIN

Their R-groups are more water soluble and can therefore pass through the porin channels of the outer membrane.

THis means they can be used to treat influenza, e. coli, listeria and salmonella

THey can still result in hypersensitivity reactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What additional side effect is associated with the aminopenicillins that is not associated with penicillin?

A

They’re more likely to cause c. diff because their spectrum is broader

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the two penicillins used as antipseudomonals?

A

Ticarcillin

Piperacillin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What combination of the antipseudomonals are given if the bacteria produces beta lactamases?

A

ticarcillin/clavulanate

piperacillin/tazobactam

17
Q

What are the symptoms of a penicillin allergy?

What percentage of the population has had an allergic response to a penicillin?

What percent will have a recurrence?

A

Symptoms include urticaria, angioedema, and anaphylasic (which can be fatal)

3-10% have had a reaction

5_10% will have a recurrence

18
Q

How does penicillin cause an allergic reaction?

A

Penicillin and other beta lactams combine with host proteins to form hapten protein complexes that stimulate the immmune system and results in production of specific antibodies to the antigen

19
Q

What drug should you use if the patient is allergic to penicillin?

Why won’t it cause cross-reactivity?

What is the spectrum?

A

Use the monobactum AZTREONAM

It won’t cause cross reactivity because it only has only one ring and is therefore less likely to form hapten proteins.

The spectrium is very narry, however, and only covers gram negative rods such as klebsiella, pseudomonas, and serratia

20
Q

Where are cephalosporins secreted?

A

in the urine

21
Q

Describe the 1st generation cephalosporins

A

CEFAZOLIN

use the same method of action as penicillins

narrow spectrum: gram + cocci

Used for surgical prophylaxis

Do NOT cross the blood brain barrier

22
Q

Describe the 2nd generation cephalosporins

A

cefoxitin

cefuroxime

They have better gram - activity than gram +

Used immedately prior to surgery to prevent infection

Don’t cross the blood brain barrier

Can inhibit Vitamin K production to prolong bleeding and will cause a disulfiram-like reaction when coadministered with ethanol

23
Q

Describe the 3rd generation cephalosporins

A

Ceftriaxone

Cefotaxime

Ceftazidime

These are used for streptococci and more serious Gram - infections resistant to other beta-lactams

CAN cross the blood brain barrier–used for meningitis

cetriaxone will interact with calcium containing meds to form crystals that precipitate in lungs and kidneys

STRONG association with C. diff

24
Q

Describe the 4th generation beta lactams

A

Cefepime

This has the broadest spectrum of the cephalosphorins because it’s a 1st generation combined with a 3rd generation

It’s used against Gram +, gram - (including pseudomonas)

Often used for empiric therapy

25
Q

Describe the 5th generation cephalosporin

A

Ceftaroline

It’s engineerd to bind to PBPs that have been mutated in MRSA infections

!!!!!!!

26
Q

What makes carbapenems unique among the beta lactams?

A

They have a low susceptibility to beta lactamases

27
Q

Describe the carbapenems

A

Imipenem (given with cilastatin)

meropenem

They containe beta lactam rings and bind to PBPs

Broad spectrum, but MRSA is resisant

Administered parenterally

Low susceptibility to beta lactamases

28
Q

What drug is always given with imipenem?

A

Imipenem is administered with cilastatin to decrease inactivation of the drug by renal dehydropeptidase I and prevent formation of potentially toxic nephrotoxic metabolite.

29
Q

What does vancomycin do?

WHat is its target?

WHat is it’s spectrum?

A

It is not a beta-lactam but it does block cell wall synthesis

It binds with high affinity to the D alanyl D alanine terminues of the cell wall precursor unit, inhibitin release form the bactoprenol carrier, thus preventing peptidoglycan synthesis. It inhibits the polymerization or the transglycosylase reaction.

It’s bactericidal

It’s spectum is narrow: gram + BUT it’s especially reserved for MRSA and C. difficile treatment

30
Q

WHy is vancomycin given orally for the treatment of C. diff, but IV for the treatment of other infections?

A

Because oral vanco is poorly absorbed, which is good for C diff because it needs to reach the colon, but bad for, say, a skin infection

31
Q

How has enterococci developed resistance to vancomycin?

A

It replaced the D-alanyl-D-alanine with a D-alanyl-D-latate or a D-alanyl-D-serine

This prevents the vanco from binding to its target

32
Q

What are the toxicities of vancomycin?

A

It causes hypersensitivity reactions often

Ototoxicity and Nephrotoxicity if toxic levels are reached due to renal insufficiency

33
Q

How does bacitracin work?

What is it used for? Why?

A

It prevents the dephosphorylation of the bactoprenol lipid carrier, thus continued elongation of the peptidoglycan cell wall cannot occur.

It is never used systemically because it is highly nephrotoxic, but it can be used occasionally in TOPICAL ophthalmic and dermatologic preparations

34
Q

Describe polymyxin B

A

It works by binding to phosphatidylethanolamine in the membrane, creating holes leading to the release of cellular contents

Spectrum: used on multidrug resistant gram negative bacteria including pseudomonas

Side effects are nephrotoxicity

Resistance is infrequent and slow to develop

cross resistance does NOT happen with any other ABx

35
Q

Describe daptomycin

A

Daptomycin binds to the cell membrane to gram positive bacteria leading to depolarixation of membrane and cell death

This is bactericidal

Used to treat Gram positive organisms and is effective against MRSA

36
Q

How does resistance to daptomycin occur?

A

resistance occurs by the addition of a positively charged lysin to the cell surface, which repels the positively charged drug

This does not cause cross-resistance

37
Q

WHat two antibiotics target the cell membrane?

Which is used for gram negative and which is used for gram positive?

A

Polymyxin B (for gram negative)

Daptomycin (gram positive)

38
Q

What antibiotics can be used to treat MRSA?

A

Vancomycin

Daptomycin

Ceftaroline (5th Gen)

39
Q

What antibiotics can be used to treat pseudomonas

A

Piperacillin

Ticarcillin

Cefepime (4th Gen)

Polymyxin B

Foundations of Medicine Week 3 (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions