Miscellaneous Protein Synthesis Inhibitors
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Questions and Answers

Which of these conditions is NOT a common adverse effect of Clindamycin?

  • Skin Rashes
  • Aplastic Anemia (correct)
  • Severe Diarrhea
  • Hepatic Dysfunction

    • What is the mechanism of action of Clindamycin?

  • Inhibition of protein synthesis (correct)
  • Inhibition of DNA synthesis
  • Inhibition of cell wall synthesis
  • Inhibition of RNA synthesis

    • What bacterial group is NOT effectively targeted by Clindamycin?

  • Gram-positive anaerobes
  • Gram-negative anaerobes
  • Gram-positive aerobes
  • Gram-negative aerobes (correct)

    • Which of the following is a potential consequence of Clindamycin use?

    <p>Overgrowth of C. difficile (D)</p> Signup and view all the answers

    What is a major use of Clindamycin in clinical practice?

    <p>Treatment of severe infections due to anaerobes (C)</p> Signup and view all the answers

    Which of these is NOT a mechanism of resistance to Clindamycin?

    <p>Increased permeability of the bacterial cell wall (C)</p> Signup and view all the answers

    Which of these is a condition for which Chloramphenicol is used as a back-up drug?

    <p>Severe salmonella infections (C)</p> Signup and view all the answers

    Which of the following is TRUE about the relationship between Clindamycin and Macrolides?

    <p>They share the same mechanism of action but are chemically unrelated (C)</p> Signup and view all the answers

    Which of the following is NOT a possible adverse effect of Linezolid?

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

    Which of the following bacterial species is NOT effectively treated by Linezolid?

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

    What is the mechanism of action of Linezolid?

    <p>Inhibition of protein synthesis (A)</p> Signup and view all the answers

    Which of the following is a characteristic of Quinupristin-Dalfopristin (Synercid)?

    <p>It inhibits CYP3A4 (C)</p> Signup and view all the answers

    Which of the following mechanisms is responsible for the development of resistance to Quinupristin-Dalfopristin?

    <p>Methylation of the drug binding site (B)</p> Signup and view all the answers

    What is the ratio of Quinupristin to Dalfopristin in Synercid?

    <p>3:7 (D)</p> Signup and view all the answers

    Which of the following statements is true regarding the mechanism of action of Tedizolid?

    <p>It inhibits protein synthesis (C)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of Tedizolid?

    <p>It is primarily bactericidal in nature (D)</p> Signup and view all the answers

    What is the primary mechanism of action for Spectinomycin?

    <p>Binds to the 30S ribosomal subunit and interferes with the elongation process. (A)</p> Signup and view all the answers

    Which of the following statements regarding Chloramphenicol is FALSE?

    <p>Chloramphenicol's primary mechanism involves targeting the 30S ribosomal subunit. (B)</p> Signup and view all the answers

    What is the primary mechanism by which resistance to Chloramphenicol develops in bacteria?

    <p>Production of enzymes that modify Chloramphenicol, rendering it inactive. (A)</p> Signup and view all the answers

    Which of the following clinical uses of Chloramphenicol is TRUE?

    <p>It is occasionally used as an alternative agent for the treatment of bacterial meningitis when other options are not suitable. (A)</p> Signup and view all the answers

    Why is Spectinomycin used almost exclusively for the treatment of gonorrhea?

    <p>It is often used as an alternative treatment for patients allergic to penicillin or when gonococci are resistant to other agents. (D)</p> Signup and view all the answers

    Which of the following statements best describes the pharmacokinetic properties of Chloramphenicol?

    <p>Chloramphenicol is widely distributed throughout the body and readily crosses the blood-brain barrier. (C)</p> Signup and view all the answers

    Which of the following drugs is NOT a ribosomal-targeting antibiotic?

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

    What is one of the primary disadvantages of Chloramphenicol use despite its efficacy?

    <p>Potential for severe side effects like aplastic anemia. (C)</p> Signup and view all the answers

    Flashcards

    Chloramphenicol

    An antibiotic used for severe salmonella infections and meningitis in beta-lactam-sensitive patients.

    Gray Baby Syndrome

    A rare condition in neonates due to lack of glucuronosyltransferase, leading to drug accumulation.

    Clindamycin

    An antibiotic that inhibits protein synthesis by binding to the 50S ribosomal subunit.

    Resistance Mechanism of Clindamycin

    Resistance can occur via plasmid-mediated inactivation and methylation of binding site.

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    Adverse Effects of Clindamycin

    Includes GI irritation, severe diarrhea, skin rashes, and potential C. difficile overgrowth.

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    Clinical Uses of Clindamycin

    Effective against gram-positive aerobes and anaerobes, especially Bacteroides.

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    Clindamycin in Endocarditis Prophylaxis

    Recommended for patients allergic to penicillin with valvular disease.

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    Drug Interactions of Chloramphenicol

    Inhibits metabolism of drugs like phenytoin and warfarin, increasing their effects.

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    Linezolid

    An oxazolidinone antibiotic that binds to 23S ribosomal RNA to inhibit bacterial protein synthesis.

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    Mechanism of Linezolid

    Binds to the 50S ribosomal subunit preventing 70S complex formation.

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    Tedizolid

    Antibiotic used for complicated skin and skin-structure infections.

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    Quinupristin-Dalfopristin

    A combination antibiotic (Streptogramins) used for resistant bacterial infections.

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    Resistance to Quinupristin-Dalfopristin

    Resistance can arise through methylation of the ribosome.

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    Adverse effects of Linezolid

    Possible thrombocytopenia, serotonin syndrome, and bone marrow suppression.

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    Bactericidal vs. Bacteriostatic

    Linezolid is bacteriostatic against Enterococci/Staphylococci, but bactericidal against Streptococci.

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    Spectinomycin

    An aminocyclitol antibiotic active against gram-positive and gram-negative bacteria, used for gonorrhea treatment.

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    Mode of action of Spectinomycin

    Binds to the bacterial 30S ribosomal subunit, interfering with protein elongation.

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    Clinical use of Spectinomycin

    Used primarily as an alternative treatment for gonorrhea in penicillin-allergic patients.

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    Mechanism of action of Chloramphenicol

    Inhibits peptide bond formation by blocking tRNA binding, affecting protein synthesis.

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    Pharmacokinetics of Chloramphenicol

    It can be administered orally or parenterally and crosses blood-brain barrier easily.

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    Resistance to Chloramphenicol

    Plasmid-mediated resistance through the formation of acetyltransferases that inactivate the drug.

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    Clinical consideration of Chloramphenicol

    It is a toxic drug and rarely used systemically due to potential side effects.

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    Study Notes

    Miscellaneous Protein Synthesis Inhibitors

    • Spectinomycin:

      • Related aminocyclitol antibiotic lacking amino sugars and glycosidic bonds.
      • Active against gram-positive and gram-negative organisms.
      • Bacteriostatic.
      • Binds to the bacterial 30S ribosomal subunit, interfering with elongation.
      • Primarily used as an alternative treatment for gonorrhea in penicillin-allergic patients or when gonococci are resistant to other agents.
      • Administered intramuscularly as a single dose of 2 grams (40mg/kg body weight).
      • Possible side effects include injection site pain, fever, nausea, nephrotoxicity, and anemia (rare).

    • Chloramphenicol:

      • Broad-spectrum antibiotic with bacteriostatic activity.
      • Active against aerobic and anaerobic gram-positive and gram-negative organisms, including Rickettsia.
      • Effective orally and parenterally.
      • Distributed throughout tissues, including crossing the placental barrier.
      • Brain tissue concentration can equal serum concentration.
      • Primarily deactivated through conjugation with glucuronic acid (in liver) or reduction to inactive aryl amines.
      • Alternative treatment for beta-lactam-resistant bacterial meningitis.
      • Toxicity concerns: Gl disturbances, red blood cell maturation inhibition (bone marrow), rare aplastic anemia, gray baby syndrome (neonates).
      • Used with caution due to potential cyanosis and cardiovascular collapse.
      • Inhibits CYP3A4.
      • Resistance can be plasmid-mediated via acetyltransferases.

    • Clindamycin:

      • Lincosamide antibiotic, inhibitor of protein synthesis.
      • Binds to the 50S ribosomal subunit.
      • Prevents chain elongation.
      • Not chemically related to macrolides, but mechanism of action is similar.
      • Resistance is plasmid-mediated via inactivating enzymes and methylation of binding sites on the 50S subunit.
      • Cross-resistance with lincosamides and macrolides.
      • Clinical uses include treatment of gram-positive aerobes, and gram-positive/negative anaerobes.
      • Indicated in refractory bone infections and severe infections due to certain anaerobes like Bacteroides.
      • Prophylaxis for endocarditis in penicillin-allergic patients.
      • Possible side effects: GI irritation (severe diarrhea), skin rashes, neutropenia, liver dysfunction, superinfections (e.g., C. difficile colitis), prolonged effects of neuromuscular blocking agents.
      • Recommended as an alternative antibiotic after amoxicillin for prophylactic coverage of patients at risk for dental/oral procedures induced bacterial endocarditis or endarteritis.

    • Linezolid (Zyvox) & Tedizolid (Sivextro):

      • Oxazolidinones.
      • Binds to 23S ribosomal RNA on 50S ribosome, preventing 70S complex formation.
      • Distributed to well-perfused tissues.
      • Primarily non-renal excretion.
      • Active against aerobic gram-positive organisms (including VRE, MRSA, Group B strep, Strep pneumoniae).
      • Used in severe infections (e.g., pneumonia, skin infections).
      • Bacteriostatic against Enterococci and Staphylococci, bactericidal against Streptococci.
      • Potential side effects include thrombocytopenia, serotonin syndrome, bone marrow suppression, diarrhea, rash, nausea.
      • Tedizolid specifically used in complicated skin infections.

    • Quinupristin-Dalfopristin (Synercid):

      • Streptogramins, A and B (ratio 3:7).
      • Inhibits protein synthesis by binding to the 50S ribosome, preventing transfer and elongation.
      • Additive inhibition by both agents.
      • Used in vancomycin-resistant enterococcus faecium, MSSA or MRSA, VRSA, and Strep. Pyogenes infections.
      • Treat soft tissue infections, pneumonia, bacteremia.
      • No activity against E. faecalis.
      • Metabolises via non-enzymatic reactions.
      • Inhibits CYP3A4.
      • Potential bacterial resistance via methylation.
      • Potential side effects include abdominal pain, acute respiratory distress syndrome (ARDS), myalgia, and hepatic transaminase activity.

    • Lefamulin (Xenleta):

      • Pleuromutilin antibiotic.
      • Unique mechanism of action: Binding to 50S ribosome, closing the binding pocket, and preventing transfer RNA binding.
      • Active against lower respiratory tract pathogens like Streptococcus pneumoniae, Haemophilus influenzae, and atypical pathogens.
      • Active against most aerobic gram-positive organisms (including S. pyogenes, S. aureus, and Enterococcus faecium).
      • Lacks activity against Enterococcus faecalis, Pseudomonas aeruginosa, and Enterobacteriaceae.
      • Approved for oral and intravenous use in community-acquired pneumonia (CAP).

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    Related Documents

    Lec 26. Chloramphenicol, Clindamycin, etc, Dr. Thomas Panavelil- FS PDF

    Description

    Explore the details of miscellaneous protein synthesis inhibitors like Spectinomycin and Chloramphenicol. This quiz covers their mechanisms of action, uses, and potential side effects. Test your knowledge on antibiotic therapy and bacterial resistance!

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