Antimicrobial Agents Quiz
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Questions and Answers

What are cell wall synthesis inhibitors?

These are antibiotics that inhibit the synthesis of bacterial cell walls.

Name two anti-pseudomonal penicillins.

Carbenicillin and Ticarcillin

What is a narrow-spectrum penicillin? Give an example.

It is an antibiotic that is effective against a limited range of bacteria. An example is Penicillin V.

How can you prevent antibacterial resistance?

<p>Antibiotic resistance can be prevented by using antibiotics appropriately, completing the entire course of treatment, and avoiding unnecessary use of antibiotics.</p> Signup and view all the answers

Name two beta-lactamase inhibitors. What is their clinical importance?

<p>Two examples of beta-lactamase inhibitors are clavulanate and sulbactam. They are clinically important because they prevent the breakdown of penicillin by the enzyme beta-lactamase, thereby enhancing the effectiveness of penicillin in treating infections.</p> Signup and view all the answers

Name two cephalosporins.

<p>Two examples are Cefadroxil and Cefaclor.</p> Signup and view all the answers

What is the spectrum of activity for different generations of cephalosporins?

<p>First-generation cephalosporins are effective against gram-positive bacteria. Second-generation cephalosporins are effective against both gram-positive and some gram-negative bacteria. Third-generation cephalosporins can treat many gram-negative bacteria but they are less effective against gram-positive bacteria, and they are more effective against Pseudomonas aeruginosa. Fourth-generation cephalosporins are resistant to degradation by bacterial enzymes and are effective against both gram-positive and gram-negative bacteria including Pseudomonas aeruginosa. Fifth-generation cephalosporins can treat Methicillin-resistant Staphylococcus aureus (MRSA).</p> Signup and view all the answers

Which of the following are common side effects of aminoglycosides?

<p>Neuromuscular block</p> Signup and view all the answers

What are macrolides? Name three examples.

<p>Macrolides are a class of antibiotics that contain a macrocyclic lactone ring. Examples include Erythromycin, Clarithromycin, and Azithromycin.</p> Signup and view all the answers

What is the mechanism of action of macrolides?

<p>Inhibition of bacterial protein synthesis by binding to 50S ribosomal subunits</p> Signup and view all the answers

What are aminoglycosides? Name three examples.

<p>Aminoglycosides are antibiotics containing amino sugars in a glycosidic linkage. Examples include Streptomycin, Gentamicin, and Tobramycin.</p> Signup and view all the answers

What is the mechanism of action of aminoglycosides?

<p>Inhibition of bacterial protein synthesis by binding to 30S ribosomal subunits</p> Signup and view all the answers

What are the major toxic effects of aminoglycosides?

<p>The major toxicities of aminoglycosides are ototoxicity and nephrotoxicity.</p> Signup and view all the answers

What is the difference between bacteriostatic and bactericidal antibiotics?

<p>Bacteriostatic antibiotics inhibit the growth of bacteria, while bactericidal antibiotics kill bacteria directly.</p> Signup and view all the answers

What is meant by "spectrum of activity" of an antibiotic?

<p>The spectrum of activity of an antibiotic defines the range of bacteria against which it is effective. It can be broad spectrum, effective against many different types of bacteria, or narrow spectrum, effective against only a specific group.</p> Signup and view all the answers

Clarithromycin is highly effective against gram-positive bacteria.

<p>False</p> Signup and view all the answers

Azithromycin has a long half-life, making it suitable for once-daily dosing.

<p>True</p> Signup and view all the answers

Aminoglycosides are typically administered orally for local action in the gastrointestinal tract.

<p>False</p> Signup and view all the answers

Aminoglycosides are effective against a wide range of bacterial infections, including those caused by gram-positive and gram-negative bacteria.

<p>False</p> Signup and view all the answers

What are the main uses of erythromycin?

<p>Erythromycin is used to treat infections, such as diphtheria, respiratory infections, skin infections, and acne. It is also used in patients allergic to penicillin.</p> Signup and view all the answers

Why is clindamycin often used in the treatment of peptic ulcer disease?

<p>Clindamycin is often used to eradicate Helicobacter pylori, a bacterium that is known to cause peptic ulcers. It is commonly used in combination with other medication.</p> Signup and view all the answers

What are the major uses of streptomycin?

<p>Streptomycin is primarily used to treat tuberculosis, tularemia, plague, and brucellosis, as well as certain sexually transmitted diseases.</p> Signup and view all the answers

What are the main uses of gentamicin?

<p>Gentamicin is used to treat serious gram-negative infections, infections of unknown etiology, UTIs, pneumonia, and meningitis. It is often used synergistically with penicillins in the treatment of enterococcal endocarditis.</p> Signup and view all the answers

Tetracyclines work by inhibiting bacterial protein synthesis by acting on the 50S ribosomal subunit.

<p>False</p> Signup and view all the answers

Aminoglycosides are effective against a wide variety of bacteria, including Mycobacterium tuberculosis.

<p>True</p> Signup and view all the answers

Which of the following antibiotics are bacteriostatic?

<p>Erythromycin</p> Signup and view all the answers

Name two antibiotics that are primarily bacteriostatic in their action.

<p>Two antibiotics primarily bacteriostatic in their action include Erythromycin and Tetracycline.</p> Signup and view all the answers

Name two antibiotics that are primarily bactericidal in their action.

<p>Two antibiotics primarily bactericidal in their action are Penicillin and Vancomycin.</p> Signup and view all the answers

Provide two examples of antibiotics that are mainly used for treating gram-negative infections.

<p>Two antibiotics that are primarily used for treating gram-negative infections include Gentamicin and Amikacin.</p> Signup and view all the answers

List three specific infections for which azithromycin is often used as treatment.

<p>Azithromycin is often used in treating community-acquired pneumonia, pharyngitis, and sexually transmitted diseases.</p> Signup and view all the answers

Study Notes

Cell Wall Synthesis Inhibitors

  • Antibiotics that inhibit cell wall synthesis are a class of drugs.

Anti-Pseudomonal Penicillin

  • Two examples, not specified.

Narrow Spectrum Penicillin

  • One example, not specified.

Preventing Antibacterial Resistance

  • Methods for preventing resistance are not specified.

Beta-Lactamase Inhibitors

  • Two examples, not specified.

Cephalosporins

  • Clinical importance of cephalosporins is not specified.
  • Two cephalosporins are specified.
  • Spectrum of different generations of cephalosporins is described.

Classification of Cephalosporins

  • Shows different generations (first, second, third, fourth, fifth) with examples of each.
  • Gram positive and Gram negative bacteria are mentioned with + or - signs indicating the spectrum of activity.
  • Shows Pseudomonas and MRSA coverage.

Antimicrobial Agents 3: Macrolides and Aminoglycosides

  • Chemical structures of macrolides and aminoglycosides.

Specific Learning Outcomes

  • Students should be able to list, describe, and discuss macrolide and aminoglycoside antibiotics.
  • Including mechanisms of action, uses, adverse effects, and combinations.

Macrolides

  • Contain a macrocyclic lactone ring to which deoxy sugars are attached.
  • Examples include erythromycin, clarithromycin, azithromycin, and clindamycin.

Macrolide Characteristics

  • Broad spectrum of activity.
  • Bacteriostatic drugs; high doses may be bactericidal.
  • Similar antibacterial spectrum to penicillin G.
  • Preferred in patients allergic to penicillin.
  • Effective against Gram-positive cocci (e.g., streptococci, some pneumococci, staphylococci), some other bacteria.

Macrolide Mechanism of Action

  • Inhibit bacterial protein synthesis by acting on 50S ribosomes.
  • Block translocation and prevent initiation complex formation.

Macrolide Adverse Drug Reactions (ADRs)

  • Generally well-tolerated.
  • Possible gastrointestinal (GI) upset and superinfections.
  • Erythromycin estolate is hepatotoxic; stearate is safer during pregnancy.
  • Erythromycin and clarithromycin are enzyme inhibitors.

Macrolide ADME

  • Acid-sensitive; administered as enteric-coated tablets or esters (e.g., estolate or stearate).
  • Crosses the placenta and prostate, secreted into bile and milk.
  • Azithromycin concentration in phagocytes is much higher than in the blood.

Macrolides - Uses

  • Substitute for penicillin in penicillin-allergic patients or for penicillin-resistant organisms.
  • Used in diphtheria, respiratory infections, neonatal infections, lymphogranuloma venereum, syphilis, mycoplasma pneumoniae, etc.
  • Elimination of corynebacterium diphtheriae carrier state.
  • Acne treatment.
  • Eradication of Helicobacter pylori in peptic ulcer treatment.
  • Outpatient therapy for community-acquired pneumonia, sexually transmitted diseases, etc.

Clarithromycin

  • More effective than erythromycin against intracellular organisms (e.g., Mycoplasma pneumoniae, Haemophilus influenzae, and H. pylori).
  • Given twice daily (e.g., twice a day) due to its long-acting nature.
  • Less gastric irritation than erythromycin.
  • Used to prevent peptic ulcer relapse.

Azithromycin

  • More active against H. influenzae and N. gonorrhoeae than erythromycin.
  • Extensive tissue distribution, including phagocytes.
  • Higher concentrations in tissues than in blood, leading to enhanced intracellular bacterial killing.
  • Absorbed well orally; given once daily (e.g., once a day if it has a long half-life and for 3-5 days).
  • Fewer drug interactions than other macrolides.
  • Suitable for outpatient treatment of community-acquired pneumonia (CAP), pharyngitis, and sexually transmitted diseases.

Aminoglycosides

  • Antibiotics containing amino sugars in glycosidic linkage.
  • Primarily used for aerobic gram-negative infections.
  • Spectrum includes E. coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Enterobacter.
  • Two natural compounds include streptomycin and gentamicin.
  • Examples of semi-synthetic compounds include kanamycin, tobramycin, amikacin, and netilmicin.

Aminoglycosides—Common Features

  • Bactericidal; inhibit bacterial protein synthesis.
  • Narrow spectrum; primarily effective against aerobic gram-negative bacteria.
  • Not absorbed orally; act locally on the GIT.
  • Systemic administration using parenteral routes.
  • Poor penetration into the blood-brain barrier and cells.
  • Significant side effects include ototoxicity, nephrotoxicity, and neuromuscular blockade.
  • Short half-life.
  • Narrow therapeutic index.

Aminoglycosides—Mechanism of Action

  • Bind to 30S ribosomal subunits and irreversibly inhibit protein synthesis.
  • Interfere with initiation complex formation.
  • Cause incorrect amino acid incorporation.

Aminoglycosides—Treatment Regimen

  • Administered repeatedly every 8 hours.
  • Concentration of aminoglycosides killing bacteria is high.
  • Once-daily dosing is preferred due to fewer side effects and better tolerability.
  • Less toxic; suitable for outpatient therapy; lower cost.

Aminoglycosides—ADME (Absorption, Distribution, Metabolism, Excretion)

  • Absorbed little from GIT; administered parentally for systemic action.
  • Non-inactivated in the GIT; can be given orally for local action.
  • Limited tissue distribution; little penetration into cells or cerebrospinal fluid (CSF).
  • Cross the placenta and affect the fetus.
  • Excreted by kidneys in active form.
  • High risk of ototoxicity and nephrotoxicity.

Aminoglycosides—Uses

  • Streptomycin: Tuberculosis, tularemia, plague, brucellosis, bacterial endocarditis (with penicillin), sexually transmitted diseases (e.g., granuloma venereum).
  • Gentamicin: Severe gram-negative infections, serious infections of unknown etiology, urinary tract infections (UTIs), pneumonia, meningitis. Used with penicillins or cephalosporins for Pseudomonas infections.
  • Enterococcal endocarditis—synergistic effect with penicillin.

Aminoglycosides—Precautions/Contraindications

  • Significant side effects including ototoxicity and nephrotoxicity.

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AMA3 - Std Copy PDF - Antimicrobial Drugs

Description

Test your knowledge on various antimicrobial agents, focusing on cell wall synthesis inhibitors, penicillins, cephalosporins, and antimicrobial resistance. Explore the classification and spectrum of activity of these important drugs, including macrolides and aminoglycosides.

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