Antimicrobials and Chemotherapeutic Agents
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Questions and Answers

What is the primary function of chemotherapeutic agents?

  • To enhance bacterial cell wall formation
  • To selectively act against microbes or malignant cells (correct)
  • To affect body cells
  • To promote microbial growth

    • What is true about all antibiotics?

  • They can target body cells
  • They are not always antimicrobials
  • They are produced from microbes (correct)
  • They are always bactericidal

    • What is the term for the destruction or dissolution of bacterial cells?

  • Bacteriostatic
  • Bactericidal
  • Antibiotic
  • Bacteriolytic (correct)

    • What is characteristic of Gram positive bacterial cell walls?

    <p>Thick cell wall</p> Signup and view all the answers

    Who is considered the 'Father of Chemotherapy'?

    <p>Paul Ehrlich</p> Signup and view all the answers

    What was discovered by Fleming, Chain, and Florey?

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

    In what year were sulphonamides discovered?

    <p>1935</p> Signup and view all the answers

    What is true about the outer membrane of Gram negative bacteria?

    <p>It is a barrier to the diffusion of antibiotics</p> Signup and view all the answers

    What is the mechanism of action of β-lactams?

    <p>Inhibitors of cell wall synthesis</p> Signup and view all the answers

    Which of the following antibiotics is an inhibitor of cell membrane leakage?

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

    What is the mechanism of action of sulfonamides?

    <p>Inhibitors of folate synthesis</p> Signup and view all the answers

    What is the classification of Ampicillin based on its spectrum of activity?

    <p>Extended spectrum</p> Signup and view all the answers

    Why are human cells not affected by β-lactams?

    <p>Human cells do not have a cell wall</p> Signup and view all the answers

    What is the characteristics of penicillins that make them ideal antibiotics?

    <p>Low direct toxicity and broad spectrum of activity</p> Signup and view all the answers

    Which of the following antibiotics is an inhibitor of DNA-dependent RNA polymerase?

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

    What is the difference between human and bacterial cells that makes antibacterial therapy possible?

    <p>All of the above</p> Signup and view all the answers

    What is the name of the first penicillin available?

    <p>Penicillin G</p> Signup and view all the answers

    Which type of bacteria is Penicillin G active against?

    <p>Most gram-positive bacteria, gram-negative cocci, anaerobic bacteria, and spirochetes</p> Signup and view all the answers

    What is the preferred drug for pharyngitis caused by Streptococcus pyogenes?

    <p>Penicillin G</p> Signup and view all the answers

    What is the preferred drug for infections caused by Bacillus anthracis?

    <p>Penicillin G</p> Signup and view all the answers

    What is the primary treatment for meningitis caused by Neisseria meningitidis?

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

    What is the drug of choice for syphilis?

    <p>Penicillin G</p> Signup and view all the answers

    What is the name of the spirochete that causes syphilis?

    <p>Treponema pallidum</p> Signup and view all the answers

    What is the characteristic of Penicillin G?

    <p>Narrow-spectrum agent</p> Signup and view all the answers

    What is the main difference between penicillin V and penicillin G?

    <p>Penicillin V is stable in stomach acid</p> Signup and view all the answers

    What is a common side effect of penicillins?

    <p>All of the above</p> Signup and view all the answers

    What is the purpose of β-lactamase resistant penicillins?

    <p>To treat infections caused by penicillinase-producing staphylococci</p> Signup and view all the answers

    What is the term used to describe staphylococcal strains that are resistant to methicillin and other penicillinase-resistant penicillins?

    <p>Methicillin-resistant Staphylococcus aureus</p> Signup and view all the answers

    What is the treatment of choice for methicillin-resistant Staphylococcus aureus?

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

    How is nafcillin usually administered?

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

    Which of the following is not a broad-spectrum penicillin?

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

    Which of the following is formulated for oral dosing?

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

    Why is an antipseudomonal aminoglycoside added to the regimen?

    <p>To increase killing of Pseudomonas</p> Signup and view all the answers

    What is a side effect of piperacillin?

    <p>Bleeding secondary to disrupting platelet function</p> Signup and view all the answers

    Why is piperacillin administered parenterally?

    <p>Because it is acid labile</p> Signup and view all the answers

    What is the purpose of beta-lactamase inhibitors?

    <p>To inhibit bacterial beta-lactamases</p> Signup and view all the answers

    Which of the following is a beta-lactamase inhibitor?

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

    What is the characteristic of cephalosporins?

    <p>They are bactericidal, often resistant to beta-lactamases, and active against a broad spectrum of pathogens</p> Signup and view all the answers

    What is the structure of cephalosporins?

    <p>A ß-lactam ring fused to a six-membered S-containing dihydrothiazine ring</p> Signup and view all the answers

    Who discovered the 1st cephalosporin?

    <p>Guiseppe Bortzu</p> Signup and view all the answers

    Study Notes

    Antimicrobials and Antineoplastic Agents

    • Chemotherapeutic agents selectively act against microbes or malignant cells, without affecting body cells.
    • Antimicrobials are used to treat infectious diseases caused by microbes, and antibiotics are a type of antimicrobial produced by microbes to inhibit or kill other microbes.

    Terminologies

    • Bacteriostatic: stops the growth of bacteria
    • Bactericidal: kills bacteria
    • Bacteriolytic: destruction or dissolution of bacterial cells

    Gram Positive and Gram Negative Bacteria

    • Gram positive bacteria have a thick cell wall and peptidoglycan directly accessible from the environment.
    • Gram negative bacteria have a thin cell wall, surrounded by an inner and outer membrane, with lipopolysaccharides, phospholipids, and proteins, making it a barrier to antibiotic diffusion.

    Historical Perspectives

    • 1877: Louis Pasteur discovered the phenomenon of antibiosis.
    • 1906: Paul Ehrlich coined the term "chemotherapy" and is considered the father of chemotherapy.
    • 1935: Domagk discovered sulfonamides (Prontosil to sulphanilamide).
    • 1929, 1939, 1941: Fleming, Chain, and Florey discovered penicillin from penicillium.
    • Waksman discovered streptomycin from actinomycetes and coined the term "antibiotic".

    Antimicrobial Classification

    • Classification by chemical structure (e.g., β-lactams, aminoglycosides)
    • Classification by mechanism of action (e.g., inhibitors of cell wall synthesis)
    • Classification by activity against organisms (e.g., anti-bacterial, anti-fungal)
    • Classification by spectrum of activity (e.g., narrow, broad, extended)
    • Classification by origin/source of antimicrobials

    Classification by Organism Affected

    • Anti-viral
    • Anti-bacterial
    • Anti-fungal
    • Anti-protozoal
    • Anthelmintic

    Classification by Spectrum

    • Narrow spectrum: e.g., penicillin G, streptomycin, erythromycin
    • Broad spectrum: e.g., tetracycline, chloramphenicol
    • Extended spectrum: e.g., ampicillin, amoxicillin

    Classification by Mechanism of Action

    • Cell wall synthesis inhibition: e.g., β-lactams, vancomycin, cycloserines
    • Cell membrane leakage: e.g., polypeptides, polyenes
    • Folate synthesis inhibition: e.g., sulfonamides, pyrimethamine, cotrimaxazole
    • DNA gyrase and topoisomerase inhibition: e.g., fluoroquinolones
    • RNA polymerase inhibition: e.g., rifampicin
    • Protein synthesis inhibition: e.g., aminoglycosides, tetracyclines, chloramphenicol, macrolides

    Differences in Human and Bacterial Cell Components

    • Human cells lack a cell wall (peptidoglycans = peptides + sugar)
    • Human cell membrane is different (bacteria contain hypanoids in place of sterol)
    • Human cells take preformed dihydrofolic acid (no need for PABA in humans)
    • Dihydrofolic acid reductase enzyme is different (thousand-time affinity)
    • Topoisomerase II are different (in bacteria, DNA gyrase)
    • DNA-dependent RNA polymerase is different
    • Ribosome 60S subunit for human (in bacteria, 50S)
    • Ribosome 40S subunit for human (in bacteria, 30S)

    Penicillins

    • Penicillins are bactericidal and active against a variety of bacteria, with low direct toxicity.
    • Examples: ampicillin, amoxicillin, carbenicillin, ticarcillin
    • Spectrum: narrow spectrum to broad spectrum
    • Pharmacokinetics: vary depending on the specific penicillin

    β-Lactamase Resistant Penicillins

    • Examples: flucloxacillin, methicillin, nafcillin, oxacillin, dicloxacillin
    • Spectrum: very narrow, active against penicillinase-producing staphylococci
    • Pharmacokinetics: vary depending on the specific penicillin

    Broad-Spectrum Penicillins

    • Examples: ampicillin, amoxicillin
    • Spectrum: broad spectrum, active against a variety of bacteria
    • Pharmacokinetics: vary depending on the specific penicillin

    Cephalosporins

    • Cephalosporins are beta-lactam antibiotics, similar in structure and actions to penicillins.
    • They are bactericidal, often resistant to beta-lactamases, and active against a broad spectrum of pathogens.
    • Classification: 1st generation, 2nd generation, 3rd generation
    • Examples: cephalexin, cefuroxime, cefamandole

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    Description

    This quiz covers the basics of antimicrobials and chemotherapeutic agents, including their selective action against microbes or malignant cells.

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