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DnD Unit 4 > Antibacterial Agents 1: Introduction > Flashcards

Antibacterial Agents 1: Introduction Flashcards

1
Q

What is selective toxicity?

A

Selective Toxicity is where an antibiotic exerts its effect SELECTIVELY on the microbe and NOT on the host.

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2
Q

What are the 4 “types” of selective toxicity?

A
  1. Inhibition of a metabolic pathway found in bacteria but not in humans
  2. Inhibition of a Enzyme that is different in host and bacteria.
  3. Disrupt macromolecular structure that does not exist in humans
  4. Disrupt macromolecular structure that differs between microbes and humans
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3
Q

Give an example of Inhibition of a metabolic pathway found in bacteria but not in humans.

A

Folate Metabolism:

Mammals take up folate from environment whereas bacteria synthesize their own.

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4
Q

Give an example of inhibition of a Enzyme that has different structure in host vs bacteria.

A
  1. Ribosomal proteins (30/50S in bacteria vs 40/60 in eukaryotes)
  2. DNA Gyrase (bacteria) vs Topoisomerase (host)
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5
Q

Give an example of a Macromolecular structure that doesn’t exist in humans but does in bacteria:

A

Cell Wall: peptidoglycan synthesis does not occur in humans.

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6
Q

Give an example of a Macromolecular structure that differs in humans compared to microbes:

A

Cell Membrane:
Funguses have Ergosterol as the major CM component
Eukaryotes have cholesterol

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7
Q

What is the difference between Narrow (intrinsic) Resistance, Escape resistance, and Acquired Resistance?

A

Narrow- Microbe LACKS TARGET for drug action.

Escape- Microbe IS susceptible, but escapes consequences due to availability of certain biomolecules or failure to lyse.

Acquired- Selective pressure produces organisms that are increasingly resistant.

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8
Q

Within the realm of Escape resistance, what causes the “escape” ability?

A
  1. Purulent infection → release of purines, thymidine, serine, methionine → microbe escapes → sulfonimide resistance

*That’s why surgical drainage procedures are so important!

  1. Failure to “lyse” due to osmotic pressure difference → penicillin resistance
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9
Q

What are the two modes of Acquired resistance?

A
  1. Mutational (Chromosomal) Resistance
    - Arises after multiple generations of replication
    - Slight resistance
    - Proper dosing and duration prevents
  2. Plasmid Mediated Resistance
    - Resistance may occur during single course of treatment
    - Plasmid exchange via conjugation, transduction, or transformation
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10
Q

A drug that has only gram positive effectivity would be classified as a ____________ spectrum?

Narrow, Extended, or Broad

A

Narrow

Either Gram + OR -, but not both.

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11
Q

True or False: Extended and Broad spectrum antibiotics are effective against both gram + and - bacteria.

A

True

Extended = + and -
Broad= + and - and atypical organisms
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12
Q

When would you use a broad spectrum antibiotic?

A

When the causative microbe is unknown in a severe infection. Switch to narrow spectrum as soon as possible

Broad spectrum therapy is aka Empiric therapy.
Definitive therapy=Known pathogens and Narrow therapy

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13
Q

What are the 5 types of mechanisms of resistance for bacteria?

A
  1. Decreased Entry (natural resistance)
  2. Bypass Pathway
  3. Altered Target Site (drug cant bind)
  4. Efflux Pump
  5. Enzymatic Degradation of drug

Dees Bacteria Are Effing Easy

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14
Q

How can we as physicians prevent increasing resistance to antibiotics?

A
  1. Use only when NEED IS ESTABLISHED
  2. Select antibiotic based on SUSCEPTIBILITY TESTS
  3. Adequate DOSE AND CONCENTRATION
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15
Q

What is the difference between a bactericidal and bacteriostatic drug?

A

Bactericidal drugs kill bacteria

Bacteriostatic drugs prevent bacteria from replicating. Later the immune system takes out the bacteria.

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16
Q

Which antibiotics mechanisms are generally bactericidal?

A
  1. Inhibition of cell wall synthesis
  2. Disruption of Cell Membrane fxn
  3. Interference with DNA fxn or synthesis.
17
Q

Which antibiotic mechanisms are generally bacteriostatic?

A
  1. Inhibition of protein synthesis (except aminoglycocides)

2. Inhibition of intermediary metabolic pathways.

18
Q

True or false: Bacteriostatic drugs can compensate for immunocompromised patients.

A

False

Bactericidal drugs compensate for immunocompromised patients.

19
Q

What are some of the advantages of Bactericidal mechanisms?

A
  1. Good for Severe infections
  2. Act quickly + irreversibly
  3. Compensation of immunocompromised
  4. Can treat where normal immune system cannot (joint capsle, across blood brain barrier etc)
20
Q

What are the 4 pharmacokinetic properties we are concerned about with antibiotic selection?

A
  1. Absorption
  2. Distribution
  3. Elimination
  4. Duration of Activity
21
Q

What are 2 cons of oral antibiotics?

A
  1. Alteration of intestinal flora

2. Incomplete absorption of some drugs.

22
Q

Some drugs exhibit selective distribution (accumulation). Which drug is used to treat osteomyelitis because it accumulates in bone?

A

Clindamycin

it goes in the “cylind”rical bone

23
Q

Some drugs exhibit selective distribution (accumulation). Which drug is used to treat URIs-Pneumonia because it accumulates in pulmonary cells?

A

Macrolides

Macs help you when you hack (cough=pneumonia)

24
Q

Some drugs exhibit selective distribution (accumulation). Which drug is used to treat periodontitis and acne because it accumulates in sebum and gingival crevicular fluid?

A

Tetracyclines

25
Q

Some drugs exhibit selective distribution (accumulation). Which drug is used to treat UTIs and because it has rapid excretion in urine?

A

Nitrofurantoin

Nitrof-urine-toin

26
Q

Some drugs exhibit selective distribution (accumulation). Which drug can cause abnormal bone growth and tooth discoloration?

A

Tetracycline because it binds Ca2+ in developing bone and teeth.

27
Q

Some drugs exhibit selective distribution (accumulation). Which drug can cause ototoxicity and nephrotoxicity?

A

Aminoglycosides

28
Q

Which type or metabolism do you need to wory about genetic polymorphisms?

A

Liver metabolism.

Some drugs may metabolize faster/slower based on polymorphisms.

29
Q

What complication may arise if duration or dose of treatment is too low?

A

Resistance or recurrence of infection

30
Q

What complication may arise if the duration is too long?

A

Superinfection

31
Q

What complication may arise if the dose is too high?

A

Dose-related toxicities.

32
Q

Which of the following is not an example of direct toxicity?

  1. Nausea and vomiting
  2. Liver failure
  3. Allergic reactions
  4. Neurotoxicity
  5. Bone marrow depression
A
  1. Allergic reactions
33
Q

What’s the stupid mnemonic for Non-renal drug elimination (also may include drug-drug interactions, hepatotoxicity, or polymorphisms)?

A

DQ-CRIMES

  1. Doxycycline
  2. Quinolones: Ciproflaxin IS renal but CYP 450 Inhibitor
  3. Clindamycin
  4. Rifampin
  5. Isoniazid
  6. Metronidazole
  7. Erythromycin-like (Azi-Clar-Ery)
  8. Sulfonamides
34
Q

What’s the stupid mnemonic for drugs that can cross the placental barrier?

A

Create A Totally Mutant Fetus:

Chloramphenicol
AminoglycosidesT
Tetracyclines
Metronidazol
Fluoroquinolones--

DnD Unit 4 (12 decks)

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