Antibiotics (Exam V) Flashcards

1
Q

What are general properties of antimicrobial agent (5)?

A
  1. Selective Toxicity - bactericidal (kills) or bacteriostatic (slow growth)
  2. Spectrum of Activity - what types of organism (gram positive, gram negative, wide, narrow)
  3. Modes of Action
  4. Side Effects
  5. Resistance of Microorganisms
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2
Q

What are the 5 main modes of action with ABX and given examples. Essay Questions

A
  1. Inhibition of cell wall synthesis (gram +): PCN, bacitracin, cephalosporin, vancomycin)
  2. Disruption of cell membrane function (gram -): polymyxin
  3. Inhibition of protein synthesis (broadest group): Tetracycline, erythromycin, streptomycin, chloramphenicol
  4. Inhibition of Nucleic Acid synthesis: Rifamycin (transcription), Quinolones (DNA replication), Flagyl
  5. Block folic acid synthesis and inhibit metabolism: sulfanilamide, trimethoprim, Bactrim
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3
Q

Name two beta-lactamase inhibitors?

Why are beta-lactamase inhibitors sometimes given with PCN?

A

Clavulanic Acid
Sulbactam

Some bacterias can produce an enzyme call beta-lactamase which breaks the beta lactam ring of PCN.

By giving drugs like Sulbactam and Clavulanic Acid, the drug combo will result in bacteria’s sensitivity to penicillin.

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4
Q

What structure is highlighted in red below?

What two antibiotic have this structure?

What type bacteria will these drugs act on?

A

β-lactam ring

Penicillin and Cephalosporin

Gram (+) cocci and Anaerobes

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5
Q

How do β-lactam containing ABX’s inhibit cell wall synthesis?

A
  • The β-lactam ring binds to enzymes that cross link the peptidoglycans that form the wall.
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6
Q

What drug is indicated by 1 on the figure below?

A

Penicillin

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7
Q

What drug is indicated by 2 on the figure below?

A

Cephalosporin

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8
Q

What type of bacteria do cell wall inhibitors work best on?

What type of bacteria do cell membrane disruptors work best on?

A

Gram +

Gram -

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9
Q

What are allergic reactions to PCN/Cephalosporins (5)?

A
  1. Anaphylactic shock (0.05%)
  2. Skin Rash (<1%)
  3. Oral Lesions
  4. Hemolytic Anemia
  5. Interstitial nephritis
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10
Q

What is the most common drug allergy that exists?

A
  • Penicillin allergy (urticaria, redness, etc.)
  • Can cross react with similar abx
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11
Q

What is an alternative to PCN?
Why?

Does it have better activity on gram positive bacteria?

A

Cephalosporins
Cephalosporins are more resistant to b-lactamase.
Cephalosporins have a broader spectrum.
Cephalosporins have less allergies than PCN.

First Gen Cephalosporins have better gram (+) activity.
Used for UTI and Staph

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12
Q

What drug is good alternative for penicillin resistant gram + bacteria (MRSA)? This is also the drug of last resort.

A
  • Vancomycin (resistant to beta-lactamase)
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13
Q

What adverse reactions can occur from vancomycin (10% adverse reaction)?

A
  • “Red-neck” Syndrome - neck flushing from histamine release
  • Ototoxicity
  • Nephrotoxicity
  • Chills/fever
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14
Q

How do cell membrane disruptors work?

What is polymyxins effective against?

A
  • Act as detergents essentially. Bind to phospholipids in membrane & create pores.

Very effective against gram (-) bacteria

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15
Q

How do tetracyclines work?

Pharmacokinetics of tetracyclines?

A

They inhibit protein synthesis (bacteriostatic)

Readily absorbed and widely distributed.

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16
Q

What drug class/antibiotic has the widest spectrum of activity?

What is the downside of this?

Why are tetracyclines not given to children?

A

Inhibition of Protein Synthesis (Tetracycline)

Tetracycline will destroy the normal intestinal microbiota and often produce severe GI disorders- bone deposition disorder.

Abnormal bone development

17
Q

What kind of structure do tetracyclines have?
Are they bacteriostatic or bactericidal?

A
  • 4-ring structure
  • Bacteriostatic
18
Q

Name the three macrolides discussed in lecture.

What advantage does one have over the other?

Spectrum covered with Macrolides?

A

-Erythromycin
-Azithromycin
-Clarithromycin

Azithromycin has a 4-5 day antibiotic course

Spectrum: (+), (-), atypicals

19
Q

What drug, discussed in lecture, binds to bacterial RNA polymerase?

A
  • Rifamycin
20
Q

How do Fluoroquinolones work?

What characteristics do these drugs have?

Types and Uses of Quinolones?

A

Inhibition of DNA gyrase (enzyme that unwinds the DNA)

Excellent gram - activity
Good gram + activity

Types: Cipro, Levaquin, Floxin
Uses: UTI, Resp tract infections, bone, joint infections

21
Q

What compound is needed to make folic acid?

What drug looks like this compound?

A

PABA

Sulfonamides

22
Q

Which drugs are inhibitors of folic acid synthesis/ antimetabolite?

A
  • Sulfonamides and Trimethoprim
23
Q

What is the mechanism of action of bacterial folic acid synthesis inhibitors?

A
  • Prevent conversion of PABA into DHF (dihydrofolic acid) → → folic acid.
24
Q

What are sulfonamides often used for?
What are they often used with?

A
  • Pneumocystitis & toxoplasmosis
  • Often paired with Trimethoprim