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MICR 262 > (LE2) Antimicrobial Drugs > Flashcards

(LE2) Antimicrobial Drugs Flashcards

(49 cards)

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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?

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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

Study These Flashcards
A

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

22
Q

Isoniazid (INH)

Study These Flashcards
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)

Study These Flashcards
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

Study These Flashcards
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
Semi-Synthetic Penicillins
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
Cephalosporins
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
Vancomycin
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
Streptomycin
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
Tetracycline
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
Chloramphenicol
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
Erythromycin
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
Rifampin
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
Amphotericin B
Type: antifungal MOA: cell membrane inhibition Preferred use: Systemic fungal infections Side effects: fairly toxic Interesting features: polyene ring disrupts ergosterol
34
Imidazoles
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
Griseofulvin
Type: antifungal MOA: mitosis inhibition (targets microtubule formation) Preferred use: under-the-nail fungal infections Side effects: Interesting features: targets keratinized tissues only
36
Acylovir
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
Anti-HIV drugs
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
Quinine derivatives
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
Metronidazole (Flagyl)
Type: anti-protozoan MOA: interferes with anaerobic metabolism Preferred use: Trichomonas (intestinal protozoan) & C. diff Side effects: Interesting features:
40
Mebendazole (Vermox)
Type: anti-helminth MOA: inhibits microtubules -> motility Preferred use: Ascaris and pinworm Side effects: X Interesting features: not absorbed by our cells
41
Niclosamide
Type: anti-helminth MOA: inhibits aerobic respiration Preferred use: tapeworms Side effects: X Interesting features: X
42
Pyrantel Pamoate (Antiminth)
Type: anti-helminth MOA: causes paralysis of worm Preferred use: hookworm, pinworm, Ascaris Side effects: X Interesting features: X
43
Antibiotic resistance is selected for by exposure to the drug. What habits/actions facilitate this?
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
What mechanism of drug resistance is shown? Give an example
Inactivate the drug with enzyme e.g. beta-lactamase for penicillin resistance
45
What mechanism of drug resistance is shown? Give an example
Alterations in membrane permeability e.g. Tetracycline kept out and can't reach target
46
What mechanism of drug resistance is shown? Give an example
Alterations in drug target e.g. Erythromycin - AA change in ribosome
47
What mechanism of drug resistance is shown? Give an example
Active transport of drug back out of the cell e.g. Pseudomonas
48
What mechanism of drug resistance is shown?
Horizontal gene transfer - R plasmid
49
How can we limit drug resistance?
- effective drug concentrations: compliance and no drug "holidays" - simultaneous drug administration (synergism/antagonism) - restricting drug prescriptions

MICR 262 (30 decks)

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