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MICR 262 > (LE2) Antimicrobial Drugs > Flashcards

(LE2) Antimicrobial Drugs Flashcards

1
Q

Describe antibiotics

A
  • naturally occurring
  • common in soil, fungi, and bacteria (competitive environment)
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2
Q

Describe synthetic Drugs. Give an example

A
  • Laboratory derived
    e.g. sulfa
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3
Q

Describe semisynthetic drugs

A

Antibiotics that are modified in the lab

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4
Q

What is selective toxicity?

A

Harms or kills the pathogen without causing significant harm to the host (magic bullet)

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5
Q

What properties are required for antimicrobial agents?

A
  • selective toxicity
  • soluble in body fluids
  • biological half-life
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6
Q

Why is body fluid solubility important for antimicrobial agents?

A

Needs water-soluble molecules so that it can be used by the body

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7
Q

Why is half-life important for antimicrobial agents?

A

affects dosing

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8
Q

What is a broad spectrum drug?

A

Works on two or more groups of bacteria

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9
Q

What is a narrow spectrum drug?

A

Works on less than or equal to one group of bacteria

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10
Q

What is the spectrum of activity for Penicillin?

A

G+, narrow spectrum

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11
Q

What is the spectrum of activity for Isoniazid?

A

Very narrow spectrum
- Works on M. tuberculosis only

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12
Q

What is the spectrum of activity for Tetracycline?

A

Very broad spectrum
G+, G-, intracellular bacteria

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13
Q

What is the spectrum of activity for Streptomycin?

A

broad spectrum, acid-fast and G-

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14
Q

What is the mode of action for the following drugs: penicillins, cephalosporins, bacitracin, and vancomycin?

A

Inhibition of cell wall synthesis (peptidoglycan, mycolic acid)
-antibacterial

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15
Q

What is the mode of action for the following drugs: chloramphenicol, erythromycin, tetracyclines, and streptomycin?

A

Inhibition of protein synthesis (70S ribosomes)
- antibacterial

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16
Q

What is the mode of action for the following drugs: quinolones and rifampin?

A

Inhibition of nucleic acid replication and transcription (DNA or RNA)
- antibacterial (DNA gyrase)
- mostly antivirals

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17
Q

What is the mode of action for polymyxin B?

A

Injury to plasma membrane (ergosterol)
- antifungal

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18
Q

What is the mode of action for the following drugs: sulfanilamide and trimethoprim?

A

Inhibition of essential metabolite synthesis (competitive or non-competitive inhibitors)
- synthetic antibacterials

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19
Q

What category of side effects is most crucial to understand when developing an antimicrobial drug?

A
  1. Toxicity - determined by selective toxicity of drug (e.g. vancomycin req monitoring of liver & kidney function)
  2. Allergies - more common in some drugs than others (e.g. penicillin and sulfa)
  3. Disruption of normal microflora - problem with broad-spectrum drugs
    • can lead to yeast infections and C. diff infections
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20
Q

What are ideal antimicrobial attributes?

A
  1. water-soluble
  2. selective toxicity
  3. biological half-life
  4. narrow spectrum
  5. low allergenicity
  6. tissue stability
  7. long shelf-life
  8. low cost
  9. low/no resistance acquisition
21
Q

Sulfonamides & Trimethoprim

A

Type: Synthetic
MOA: competitive protein inhibition. PABA analog
Preferred use: broad spectrum
Side effects:
Interesting features:

22
Q

Isoniazid (INH)

A

Type: Synthetic
MOA: inhibits mycolic acid in AF cell wall
Preferred use: Narrow spectrum; M. tuberculosis
Side effects: X
Interesting features: req 6 mo to 2 yr regiment compliance

23
Q

Quinolones (e.g. Ciprofloxacin)

A

Type: Synthetic
MOA: inhibits DNA gyrase used in DNA replication
Preferred use: Gram broad spectrum
Side effects: weakening of tendons
Interesting features: newer drug -> no resistance yet

24
Q

Penicillins

A

Type: Antibacterial
MOA: Cell wall inhibitor
Preferred use: narrow spectrum G+ Staphylococcus, Streptococcus, and some spirochetes (syphilis)
Side effects: X
Interesting features: Penicillin G (requires injection), Penicillin V (Orally, resists stomach acid)
Susceptible to beta-lactamase produced by MRSA. (carried on R plasmid)

25
Q

Semi-Synthetic Penicillins

A

Type: antibacterial
MOA: cell wall inhibitor
Preferred use: Broader spectrum than penicillin
Side effects: X
Interesting features: Still has beta-lactam ring. Combined with Clavulanate to inhibit beta-lactamase
e.g. Augmenten = Amoxicillin + Clavulanate, Methicillin

26
Q

Cephalosporins

A

Type: Antibacterial
MOA: cell wall inhibitor
Preferred use: broad spectrum
Side effects: X
Interesting features: more resistant to beta-lactamase; beta-lactam ring protected by 6-point ring structure

27
Q

Vancomycin

A

Type: antibacterial
MOA: cell wall inhibitor
Preferred use: last resort; Broad spectrum MRSA & TB
Side effects: High toxicity, req kidney & liver function monitored
Interesting features: VISA - Vancomycin intermediate S. aureus
VRSA
VRE - Vancomycin-resistant Enterococcus

28
Q

Streptomycin

A

Type: Antibacterial
MOA: Protein synthesis inhibitors
Preferred use: Broad spectrum; last resort for G- and TB
Side effects: Fairly toxic
Interesting features: Neomycin (Neosporin) topical variant

29
Q

Tetracycline

A

Type: Antibacterial
MOA: protein synthesis inhibitor
Preferred use: broad spectrum; G+, G-, intracellular pathogens (chlamydia)
Side effects: High toxicity
Interesting features: Doxycycline common for acne, STDs, and malaria (intracellular protozoan) prophylactic

30
Q

Chloramphenicol

A

Type: antibacterial
MOA: protein synthesis inhibitor
Preferred use: broad spectrum (G+/-)
Side effects: high toxicity. high penetrating power can enter bone marrow causing aplastic anemia, a type of leukemia
Interesting features: Topical use only for diabetic ulcers

31
Q

Erythromycin

A

Type: antibacterial
MOA: protein synthesis inhibitor
Preferred use: narrow spectrum, G+
Side effects: X
Interesting features: -macrocyclic ring blocked by G- cell wall
- best alternative to penicillin

32
Q

Rifampin

A

Type: antibacterial
MOA: Nucleic acid synthesis inhibitor
Preferred use: broad spectrum (G+/-)
Side effects: red/orange body fluid secretions
Interesting features: not super common

33
Q

Amphotericin B

A

Type: antifungal
MOA: cell membrane inhibition
Preferred use: Systemic fungal infections
Side effects: fairly toxic
Interesting features: polyene ring disrupts ergosterol

34
Q

Imidazoles

A

Type: antifungal
MOA: cell membrane inhibition
Preferred use: topical use; cutaneous fungal infections (athlete’s foot, yeast infection)
Side effects: X
Interesting features: Lamisil (pill form)

35
Q

Griseofulvin

A

Type: antifungal
MOA: mitosis inhibition (targets microtubule formation)
Preferred use: under-the-nail fungal infections
Side effects:
Interesting features: targets keratinized tissues only

36
Q

Acylovir

A

Type: antiviral
MOA: Inhibit viral DNA replication (nucleotide analog)
Preferred use: Herpes (HSV, shingles, etc.)
Side effects: non-selectively toxic
Interesting features: e.g. Valtrex

37
Q

Anti-HIV drugs

A

Type: antiviral

  1. MOA: reverse transcription inhibitor (AZT)
    Preferred use: HIV
    Side effects: high mutation rate, toxic in high doses
    Interesting features: nucleotide analog (adenine)
  2. MOA: protease inhibitor. inhibit last step of HIV maturation
    Preferred use: HIV
    Side effects: high mutation rate
    Interesting features: used in combination with AZT to reduce HIV replication
38
Q

Quinine derivatives

A

Type: anti-protozoan
MOA: Toxin buildup
Preferred use: antimalarial
Side effects: vivid dreams
Interesting features: Chloroquine and Mefloquine; given as prophylactic prior to travel to high-risk areas

39
Q

Metronidazole (Flagyl)

A

Type: anti-protozoan
MOA: interferes with anaerobic metabolism
Preferred use: Trichomonas (intestinal protozoan) & C. diff
Side effects:
Interesting features:

40
Q

Mebendazole (Vermox)

A

Type: anti-helminth
MOA: inhibits microtubules -> motility
Preferred use: Ascaris and pinworm
Side effects: X
Interesting features: not absorbed by our cells

41
Q

Niclosamide

A

Type: anti-helminth
MOA: inhibits aerobic respiration
Preferred use: tapeworms
Side effects: X
Interesting features: X

42
Q

Pyrantel Pamoate (Antiminth)

A

Type: anti-helminth
MOA: causes paralysis of worm
Preferred use: hookworm, pinworm, Ascaris
Side effects: X
Interesting features: X

43
Q

Antibiotic resistance is selected for by exposure to the drug. What habits/actions facilitate this?

A
  1. non-compliance
  2. incorrect dosage (self-medication)
  3. Use in animal foods
  4. Lack of prescription control
  5. use for non-bacterial infections
  6. overuse of broad-spectrum drugs
44
Q

What mechanism of drug resistance is shown? Give an example

A

Inactivate the drug with enzyme
e.g. beta-lactamase for penicillin resistance

45
Q

What mechanism of drug resistance is shown? Give an example

A

Alterations in membrane permeability
e.g. Tetracycline kept out and can’t reach target

46
Q

What mechanism of drug resistance is shown? Give an example

A

Alterations in drug target
e.g. Erythromycin - AA change in ribosome

47
Q

What mechanism of drug resistance is shown? Give an example

A

Active transport of drug back out of the cell
e.g. Pseudomonas

48
Q

What mechanism of drug resistance is shown?

A

Horizontal gene transfer
- R plasmid

49
Q

How can we limit drug resistance?

A
  • effective drug concentrations: compliance and no drug “holidays”
  • simultaneous drug administration (synergism/antagonism)
  • restricting drug prescriptions

MICR 262 (30 decks)

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