Fall '13 Quiz 1 Flashcards by Malinda Waldof

Q

What is an example of a static drug?

A

Tetracycline

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Q

What does a static antibiotic do?

A

Decreases rate of bacterial population expansion

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Q

What does a static antibiotic require to be successful?

A

A healthy host defense response

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Q

What is the method of action of Tetracycline?

A

Anti-metabolic

2. Inhibits protein synthesis

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Q

What does a cidal antibiotic drug do?

A

Kills the bacteria (cell lysis)

Reduces bacterial population numbers

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Q

What is an example of a cidal drug?

A

Penicillin

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Q

What kind of patients require cidal drugs?

A

Immunodeficient patients

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Q

How do cidal antibiotic drugs work?

A

Inhibit DNA & protein synthesis

2. Affect cell wall integrity

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Q

What do newer cidal drugs do?

A

Trigger apoptosis

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Q

What are 3 examples of newer apoptotic cidal drugs?

A

Aminoglycosides
Fluoroquinolones
Beta-lactams

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Q

How can the concentration of Penicillin influence its effect? Do different concentrations have different effects?

A

Yes!
Clinical concentrations = bacteri-cidal
Very low or high = bacterio-static

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Q

What happens when you give both cidal and static antibiotic?

A

They antagonize each other!

BAD

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Q

What is the MIC?

A

Minimum inhibitory concentration

= bacteriostatic

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Q

What is the Kirby-Baur Method?

A

MIC disk diffusion method

Only semi-quantitative

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Q

What is the broth or dilution method?

A

Quantitative

But only tests one strain

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Q

What does MICx mean?

A

x = percent of strains that are sensitive to the drug

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Q

What is the median MICx?

A

MIC50

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Q

What is MBC?

A

Minimum bactericidal concentration
Lowest drug concentration that will prevent growth of a bacteria after treatment and reculturing on antibiotic free media

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Q

Is the MBC higher or lower than the MIC value?

A

Higher

much higher than then MIC

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Q

Tetracycline:

Broad, intermediate, or narrow spectrum of activity?

A

Intermediate

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Q

Fluoroquinolones (3rd generation):

Broad, intermediate, or narrow spectrum of activity?

A

Broad

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Q

Chloramphenicol:

Broad, intermediate, or narrow spectrum of activity?

A

Broad (beta-lactam)

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Q

Carbapenems:

Broad, intermediate, or narrow spectrum of activity?

A

Broad (beta-lactam)

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Q

Cephaloporins (2nd-4th generations):

Broad, intermediate, or narrow spectrum of activity?

A

Intermediate

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Penicillin: | Broad, intermediate, or narrow spectrum of activity?

Narrow

List some drugs with concentration dependent activity.

1. Aminoglycosides 2. Fluoroloquinalones 3. Metronidazole

List some drugs with time dependent activity.

1. Beta-lactams 2. Chloramphenicol 3. Tetracyclines 4. Macrolides 5. Potentiated sulfas

What are two drugs that have a large post-antibiotic effect?

1. Aminoglycosides | 2. Tetracyclines

Name a few drugs that are weak bases?

1. Trimethoprim 2. Macrolides 3. Lincosamides

Where do drugs that are weak bases accumulate?

Acidic fluids 1. Milk 2. Ruminal fluids

What is the effect of inflammation on drug penetration?

Increased. | Esp. to protected sites like brain, prostrate & eye.

How does plasma protein binding affect how a drug is eliminated?

It reduces the rate of elimination. (glomerular filtration only) Drugs must be actively secreted into the tubules

What type of metabolism predominates for lipophilic drugs?

Hepatic.

Are sulfonamides acids or bases?

Acids.

Is trimethoprim an acid or a base?

Base.

When is a bacteria multi-drug resistant?

When it is resistant to 3 or more drug classes

What is the breakpoint concentration? What is it's significance?

Concentration above which a particular bacterium is considered significantly resistant.

What is intrinsic drug resistance?

1. Bacterial have natural barriers 2. Bacteria lacks drug target 3. Bacteria has a lot of innate resistance.

What are some groups of bacteria that have a lot in innate resistance?

1. Mycobacteria | 2. Pseudomonas

What is acquired drug resistance?

Chromosomal mutation. 1. Vertical 2. Horizontal

What forms of mutation are most clinically important?

1. Transduction (bacteriophage) | 2. Conjugation

How much do chemical alterations affect the MIC value?

100-fold change

How much to alterations in drug transport affect the MIC value?

10-fold change

Name 3 ways we can combat antimicrobial drug resistance?

1. Use combinations of drugs from different classes 2. Use the mutant prevention concentration (MPC) = LOWEST drug concentration that arrests growth 3. Keep the concentration above the mutant selection window (MIC90)

How do sulfonamides work?

Anti-metabolites that inhibit folate synthesis PABA analog Inhibit DPSase

What is a short acting sulfonamide?

Sulfa-methoxazole

What is an intermediate acting sulfonamide?

Sulta-dimethoxine

What is a sulfonamide used for GI infections?

Sulfa-salazine

What is a topical sulfonamide?

Silver sulfa-diazine

Why are triple sulfas advantageous?

Law of independent solubility = can use low concentrations of each drug = their effects are additive = keeps side effects low

What are diaminopyrimidines?

Drugs that also inhibit folic acid synthesis but at a different enzyme = DHFRase

What drug is contraindicated with sulfonamides?

Procaine penicillin. = procaine produces PABA metabolites = procaine PABA competes with PABA analogs of sulfonamide drugs

What happens when you combine sulfonamides with diaminopyrimidines?

-static + -static = -cidal!

What is the name of a specific diaminopyrimidine?

Trimethoprim

How does adding trimetoprim to sulfonamides affect the MIC value?

Reduces the MIC value

How does adding trimetoprim to sulfonamides affect the spectrum of activity?

Expands the spectrum of activity.

What is susceptible to sulfonamide + trimethoprim drugs?

1. Aerobes 2. Anaerobes 3. Atypicals = chlamydia 4. Protozoans

Which drug is given at a higher concentration: sulfonamides or trimethoprim?

Sulfonamides

What are some adverse effects of sulfonamides?

1. Renal crystalluria 2. Keratoconjunctivitis in dogs 3. Immune reactions in Dobermans

What is an adverse effect of trimethoprim?

Folate deficiency