Synthetic Antimicrobial Agents Quiz
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Questions and Answers

What is a defining feature of synthetic antimicrobial agents?

  • They are always effective against all types of infections.
  • They are exclusively used for bacterial infections.
  • They may not be accurately termed 'antibiotics.' (correct)
  • They are derived from natural products.

What was identified as the active substance resulting from the bioactivation of Prontosil rubrum?

  • Sulfasalazine
  • Aniline sulfonamide
  • Mafenide acetate
  • Sulfanilamide (correct)

Which of the following is NOT one of the classifications of sulfonamides?

  • Metal-containing sulfonamides (correct)
  • Prodrugs generating active sulfanilamides
  • Non aniline sulfonamides
  • Antibacterials that are aniline-substituted sulfonamides

Why was the dye Prontosil rubrum significant in the development of antibiotics?

<p>It selectively targeted certain pathogenic bacteria. (B)</p> Signup and view all the answers

What characteristic distinguishes sulfasalazine in the context of sulfonamides?

<p>It is a prodrug that generates active sulfanilamides. (B)</p> Signup and view all the answers

What is the pKa of the carboxyl group of PABA?

<p>6.5 (A)</p> Signup and view all the answers

Which sulfonamide is mentioned as having a pKa of approximately 5.0?

<p>Sulfisoxazole (A)</p> Signup and view all the answers

What is a consequence of sulfonamide drugs binding to plasma proteins?

<p>Displacement of other protein-bound drugs (C)</p> Signup and view all the answers

Which group is responsible for making the nitrogen in sulfanilamide partially electropositive?

<p>Sulfonamide moiety (C)</p> Signup and view all the answers

Why is sulfisoxazole acetyl preferred in pediatric preparations?

<p>It is tasteless. (C)</p> Signup and view all the answers

What factors may contribute to resistance against sulfonamides?

<p>Increased production of PABA (C)</p> Signup and view all the answers

What is the primary use of sulfadiazine in its silver salt form?

<p>Treatment of burns (C)</p> Signup and view all the answers

Which organisms are commonly susceptible to sulfisoxazole?

<p>Escherichia coli (D)</p> Signup and view all the answers

Which sulfa drug is utilized for the treatment of ulcerative colitis and Crohn's disease?

<p>Sulfazalazine (A)</p> Signup and view all the answers

What physiological process is commonly associated with the excretion of sulfonamides?

<p>Excretion by the kidney (C)</p> Signup and view all the answers

What is the most common adverse effect associated with sulfa drugs?

<p>Rash (C)</p> Signup and view all the answers

Which statement best describes the mechanism of action of Mafenide Acetate?

<p>Its antibacterial action differs from that of true sulfanilamide-type compounds. (A)</p> Signup and view all the answers

What role does dihydrofolate reductase play in bacterial metabolism?

<p>Facilitates the reduction of folic acid to tetrahydrofolic acid (C)</p> Signup and view all the answers

Which condition is least associated with sulfacetamide?

<p>Management of burns (B)</p> Signup and view all the answers

What distinguishes Silver Sulfadiazine in its mechanism of action compared to other sulfanilamides?

<p>It does not penetrate the cell wall but acts on the external structure. (B)</p> Signup and view all the answers

What potential serious adverse effects can occur with sulfa drug use?

<p>Photosensitivity and drug fever (C)</p> Signup and view all the answers

What is the standard ratio of trimethoprim to sulfamethoxazole in co-trimoxazole?

<p>1:5 (A)</p> Signup and view all the answers

Which of the following infections can co-trimoxazole treat?

<p>Pneumocystis pneumonia (D)</p> Signup and view all the answers

What are the most common side effects associated with trimethoprim-sulfamethoxazole?

<p>Rash and nausea (B)</p> Signup and view all the answers

What type of bacterial resistance to trimethoprim is increasingly common?

<p>Resistance resulting from a single amino acid mutation (D)</p> Signup and view all the answers

What is the primary therapeutic application of trimethoprim as a single agent?

<p>Treatment of uncomplicated urinary tract infections (B)</p> Signup and view all the answers

Which bacterium has been reported to overexpress dihydrofolate reductase in resistant strains?

<p>Staphylococcus aureus (A)</p> Signup and view all the answers

Co-trimoxazole is used to treat which of the following diseases?

<p>Shigellosis (B)</p> Signup and view all the answers

Which preparation forms of co-trimoxazole are available?

<p>Oral and intravenous (B)</p> Signup and view all the answers

Flashcards

Synthetic Antimicrobial Agents

Antimicrobial agents not derived from natural sources, sometimes extremely effective for treating infections.

Sulfonamides

A class of synthetic antibacterial agents often used to treat bacterial infections.

Bioactivation of Prontosil

The process where Prontosil rubrum is converted into a more active form (sulfanilamide) by the body.

Mechanism of Action (Sulfonamides)

The way sulfonamides work to inhibit bacterial growth is to competitively inhibit bacterial enzyme that produce folic acid.

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Nomenclature of Sulfonamides

Sulfonamide is a broad term encompassing aniline-substituted (sulfanilamides), prodrugs (like sulfasalazine), and non-aniline forms.

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pKa of PABA

The acidity of the carboxyl group on PABA, roughly 6.5

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Sulfonamide Moiety

The part of sulfanilamide distinguished by its structure and properties.

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Electron-withdrawing group

A group in a molecule that pulls electron density toward itself

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Sulfisoxazole pKa

The acidity of the sulfonamide group in sulfisoxazole, about 5.0

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Pharmacokinetics of Sulfonamides

How sulfonamides are absorbed, distributed, and eliminated in the body

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Oral Absorption of Sulfonamides

Sulfonamides pass through the digestive system into the bloodstream

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Plasma Protein Binding

Sulfonamides bind to blood proteins in the plasma.

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Therapeutic application of Sulfonamides

Use in treating infections because of its antibiotic properties.

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Sulfadiazine silver salt use

Topical treatment of burns.

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Sulfacetamide use

Ophthalmic (eye) treatment.

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Sulfasalazine use

Treats ulcerative colitis and Crohn's disease.

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Sulfa adverse effects

Common rash, photosensitivity, and fever. Less common: kidney/liver damage, anemia.

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Mafenide Acetate mechanism

Antibacterial action differs from other sulfa drugs; it isn't inhibited by PABA.

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Silver Sulfadiazine (Silvadene) action

Acts on the outer structure of cells; doesn't fully penetrate cell walls.

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Trimethoprim's mechanism

Inhibits dihydrofolate reductase, blocking folic acid synthesis and DNA production.

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Folic acid role in DNA

Folic acid is crucial for supplying components used in DNA synthesis.

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Trimethoprim Selectivity

Trimethoprim preferentially targets bacterial dihydrofolate reductase over the mammalian enzyme. This selectivity arises from subtle structural differences between the bacterial and mammalian enzymes.

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Co-trimoxazole

An antibiotic combination of trimethoprim and sulfamethoxazole. It exists in oral and intravenous forms and treats various bacterial infections.

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Co-trimoxazole Uses

Co-trimoxazole treats conditions like urinary tract infections, skin infections, traveler's diarrhea, respiratory tract infections, and cholera.

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Pneumocystis Pneumonia

Co-trimoxazole can be used to treat and prevent pneumocystis pneumonia, a serious lung infection common in people with HIV/AIDS.

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Trimethoprim Single Agent

Trimethoprim is sometimes used alone for oral treatment of uncomplicated urinary tract infections.

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Trimethoprim-Sulfamethoxazole Combination

This combination is used for oral treatment of various infections, including urinary tract infections, shigellosis, otitis media, traveler's diarrhea, and methicillin-resistant Staphylococcus aureus.

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Resistance to Trimethoprim

Bacterial resistance to trimethoprim is growing and can develop through various mechanisms like mutations in the dihydrofolate reductase enzyme or overexpression of the enzyme.

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Trimethoprim Side Effects

The most common side effects of trimethoprim-sulfamethoxazole are rash, nausea, vomiting, and severe drug-related diarrhea.

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Study Notes

Synthetic Antimicrobial Agents

  • Synthetic antimicrobial agents are not derived from natural products, so they aren't considered "antibiotics."
  • Some synthetic antimicrobial agents are highly effective and widely used for treating infections.

Sulfonamides

  • Prontosil rubrum, a red dye, was found to be active against streptococcal infections in vivo (in living organisms) but not in vitro (in a lab setting).
  • The active component, p-aminobenzenesulfonic acid amide (sulfanilamide), is a byproduct of Prontosil rubrum metabolism in the liver.
  • Sulfonamides are effective because they are similar to p-aminobenzoic acid (PABA), a crucial component in bacterial growth.

Bioactivation of Prontosil

  • Prontosil is converted to sulfanilamide in the body (bioactivation).

Mechanism of Action

  • Sulfonamides are structurally similar to PABA, a substrate for dihydropteroate synthase.
  • By mimicking PABA, sulfonamides prevent the production of dihydrofolic acid which is a precursor to DNA synthesis.

Nomenclature of Sulfonamides

  • Sulfonamide is a broad term, encompassing three types: -Aniline sulphonamides -Prodrugs that require activation -Non-aniline sulphonamides

Structure-Activity Relationships

  • The functional groups that differ include the carboxyl of PABA and the sulfonamide moiety of sulfanilamide.
  • The sulfonamide's aromatic ring has a strongly electron-withdrawing character causing the nitrogen atom to be partially electropositive..
  • PABA's carboxyl group has a pKa of approximately 6.5
  • Substituting one of the -NH2 groups in PABA for an electron withdrawing ring slightly decreases acidity and increases antibacterial activity.

Structure-activity relationships (continued)

  • Reducing the pKa of the sulfonamide molecule to the range of PABA improves its activity.
  • Examples: pKa of sulfisoxazole is approximately 5.0
  • Clinically useful sulfonamides vary in the heterocyclic aromatic substituents on the sulfonamide nitrogen..

Pharmacokinetics

  • Orally administered sulfonamides are well absorbed in the gastrointestinal tract, distributed widely, and eliminated by the kidney.
  • They can bind to plasma proteins.
  • Certain sulfonamides (like sulfisoxazole) can displace other protein-bound drugs and bilirubin (affecting newborns).
  • Metabolism involves acetylation and glucuronidation.
  • Resistance can occur due to decreased sensitivity of dihydropteroate synthase or increased production of PABA.

Therapeutic Applications

  • Sulfisoxazole acetyl is used in pediatric preparations due to its tasteless nature.
  • It is active against various bacterial organisms.
  • Other sulfonamides are used topically (e.g., silver sulfadiazine for burns) or ophthalmically (e.g., sulfacetamide).
  • Sulfonamides are used in the treatment of ulcerative colitis and Crohn's disease (sulfasalazine).

Co-trimoxazole

  • A combination of trimethoprim and sulfamethoxazole, used against bacterial and certain fungal infections.
  • Used for various infections, including urinary tract infections (UTIs)

Mechanism of action (Trimethoprim)

  • Trimethoprim inhibits dihydrofolate reductase, which is crucial for bacterial DNA synthesis. This prevents the production of tetrahydrofolic acid
  • The selectivity of trimethoprim against bacterial compared to mammalian enzyme arises from subtle (but significant) enzyme architectural differences.

Resistance

  • Bacterial resistance to trimethoprim is becoming more common.
  • Mechanisms of resistance involve mutations, like an amino acid change in certain enzymes, and overexpression of enzymes.

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Sulfonamides PDF

Description

Test your knowledge on synthetic antimicrobial agents, specifically sulfonamides and their mechanisms of action. This quiz covers the bioactivation of Prontosil and its impact on treating infections. Explore the structural similarities that enable sulfonamides to inhibit bacterial growth effectively.

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