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PHA 3112 > 3.3 - Inhibition of Cell Wall Synthesis (Final) > Flashcards

3.3 - Inhibition of Cell Wall Synthesis (Final) Flashcards

1
Q

Antibiotics that act on the cell wall are most effective on what bacteria?

A

–> Gram+
–> Bacteria in growth phase

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2
Q

Many antibiotics that inhibit cell wall synthesis share which common chemical structure?

A

Beta-Lactams
–> Penicillins, cephalosporins, carbapenems, monobactams

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3
Q

What are the four classification of penicillins?

A

i) Natural (narrow spectrum - Gram +)
ii) Resistant to beta-lactamases
iii) Broad spectrium
iv) Extended spectrum (Especially useful vs Pseudomonas)

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4
Q

What are the two natural penicillins?

A

Penicillin G
–> Not stable in gastric acid (administered parenterally)

Penicillin V
–> Stable in acidic environment and administered orally

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5
Q

What is penicillin G benzathine?

A

An IM administered natural penicillin G
–> Long acting, used to treat syphilis

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6
Q

Which bacteria have a lot beta-lactamase enzymes?

A

Staphylococcus aureus
–> highly enriches with beta-lactamase

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7
Q

What would you use penicillin to treat?

A

–> Group A strep - strep throat
–> Group B strep
–> Tooth infections

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8
Q

How can we use a beta-lactam antibiotic to kill a bacteria that produces beta-lactamase?

A

By administering a beta-lactamase inhibitor, such as tazobactam or clavulanic acid.

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8
Q

Would you use penicillin to treat a staph. aureus infection?

A

No. It has too much beta-lactamase and will break it down.

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8
Q

How do penicillins target bacteria?

A

They target the peptidoglycan layer

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9
Q

What kinds of drugs are tazobactam and clavulanic acid? Why would you administer them?

A

Beta-lactamase inhibitors
–> Administered alongside beta-lactam antibiotics to treat infections of bacteria with plenty as beta-lactamases (such as S. aureus)

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10
Q

Clavulanic acid + amoxicillin =

A

Clavulin

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11
Q

Tazobactam + piperacillin =

A

Tazocin or pip-tazo

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12
Q

What are the broader spectrum penicillins? What differentiates them?

A

They are effective against Gram-

–> Ampicillin (PO, IV)
–> Amoxicillin (PO) or
–> Amoxicillin (PO) + Clavulanic acid

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13
Q

What are the Beta-lactamase resistant penicillins?

A

–> Cloxacillin
–> Methicillin (not used clinically useful, but there should be no bacteria immune to it, so its immunity is concerning and we screen for it in hospitals and nursing homes MRSA)

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14
Q

What are the extended spectrum penicillins? What differentiates them?

A

Effective against Pseudomonas

–> Piperacillin + tazobactam

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15
Q

Penicillins are generally well tolerated, but what should be watched for when taking it?

A

Drug allergy (5-10%)
–> Immediate (3-20 mins)
–> Accelerated (1-2 days)
–> Delayed (3-10 days)

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16
Q

What kinds of reactions are common to penicillin?

A

–> Anaphylactic (rare)
–> Uticaria (hives)
–> Drug rash
–> Serum Sickness
–> Nephritis
–> Hemolytic anemia

17
Q

What is uticaria?

A

hives

18
Q

What is serum sickness?

A

Fever, arthralgias, and rash

19
Q

What structure do cephalospores resemble?

A

Penicillins

20
Q

How many generations of cephalosporins are there?

A

5

1st to 3rd - Activity versus gram- increases, versus Gram+ decreases

4th to 5th - add to spectrum of 3rd generation by targeting resistant bacteria including Pseudomonas & MRSA

21
Q

Name the first gen cephalosporins.

A

Cefazolin (i.v.)
Cephalexin (p.o.)

22
Q

Name the second gen cephalosporins?

A

Cefprozil
Cefuroxime

23
Q

Name the third gen cephalosporins

A

Ceftriaxone, ceftazidime, cefixime

24
Q

Name a fourth gen cephalosporin

A

Cefepime

25
Q

Name a fifth gen cephalosporin

A

Ceftobiprole

26
Q

What are some adverse effects of cephalosporins?

A

–> Hypersensitivity (very low cross-reactivity with penicillins)
–> NV&D
–> Some inhibit metabolism of alcohol and have a disulfiram-like effect

27
Q

What is disulfiram?

A

A drug that inhibits the metabolism of alcohol
–> When consumed together it causes headaches, flushing, nausea

28
Q

Describe the process of metabolizing alcohol?

A

Ethanol + alcohol dehydrogenase –> Acetaldehyde + aldehyde dehydrogenase –> Acetate

29
Q

What enzyme does disulfiram inhibit?

A

Aldehyde dehydrogenase (ALDH)

30
Q

What metabolite of alcohol causes headache, flushing, nausea and vomiting?

A

Acetaldehyde (a middle compound between ethanol and acetate)

31
Q

What kind of drug is meropenem?

A

A carbapenem

32
Q

Carbapenems:
–> Name one
–> What differentiates it

A

Meropenem
–> Resistant to B-lactamases; controlled use
–> Certain enterobacteriaceae are resistant due to producing an inactivating enzyme called New Delhi Metallo-betalactamase (NDM-1 or carbapenemase)

33
Q

What kind of drug is aztreonam?

A

Monobactam

34
Q

Why would you use aztreonam, a monobactam?

A

It acts of Gram - aerobic bacteria
–> P. aeruginosa, Neisseria, H. Influenxae and enterobacteria such as E. coli, klebsiella, proteus, serratia, salmonella, and shigella.

35
Q

What kind of drug is polysporin?

A

500 units Bacitracin + 10 000 units Polymyxin

36
Q

What kind of bacteria is targetted by bacitracin? How is it usually applied?

A

–> Targets Gram +
–> Used topically (ingredient in polysporin)

37
Q

What kind of bacteria are resistant to carbapenems?

A

Certain enterobacteriacaea (CRE) due to producing New Delhi metallo-beta-lactamase (NMD-1) / carbapenemase

38
Q

Vancomycin:
What is vancomycin used to treat?
How is it normally administered?
Adverse effects?

A

MRSA and C. diff
–> Treats very resistant or difficult to treat microorganisms

Normally given i.v.
–> Will cause flushing
–> Poor F orally, sometimes useful to treat C. diff

Adverse Effects
–> Infusion related flushing
–> Rash
–> Hypotension if administered too quickly
–> Nephrotoxicity

39
Q

Are any bacteria resistant to vancomycin?

A

Yes, called VRE

40
Q

Which drug is administered through inhalation for 28 days for P. aeruginosa for CF patients?

A

Monobactams
–> aztreonam

41
Q

What is a CRE?

A

Carbapenem Resistant Enterobacteriaceae
–> Produces carbapenemase and is resistant to carbapenems

42
Q

What is NDM-1?

A

New Delhi Metallo-beta-lactamase
–> Carbapenemase

PHA 3112 (22 decks)

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