BETA-LACTAMS Antibiotics
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Questions and Answers

What is the primary mechanism of action of beta-lactam antibiotics?

  • Inhibiting DNA replication
  • Binding to penicillin-binding proteins and inhibiting cell wall crosslinking (correct)
  • Disrupting the cytoplasmic membrane
  • Inhibiting protein synthesis

    • What is a common side effect of beta-lactam antibiotics?

  • Hypercalcemia
  • Hypernatremia
  • Hypokalemia
  • Hypersensitivity reactions (correct)

    • Which of the following beta-lactam antibiotics has activity against MRSA?

  • Amoxicillin
  • Cefepime
  • Piperacillin/Tazobactam
  • Ceftaroline (correct)

    • Why are oral beta-lactams often poor choices for serious or deep-seated infections?

    <p>They have poor bioavailability and achieve low serum concentrations</p> Signup and view all the answers

    What is the characteristic of beta-lactam antibiotics in terms of their killing mechanism?

    <p>Time-dependent killing</p> Signup and view all the answers

    What is the name of the group of organisms that have inducible, chromosomal beta-lactamases and may lead to resistance to beta-lactams?

    <p>SPICE-A</p> Signup and view all the answers

    Which of the following beta-lactam antibiotics is not affected by the inducible, chromosomal beta-lactamases of the SPICE-A organisms?

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

    Why are beta-lactam antibiotics preferred in many situations?

    <p>They have high efficacy and are bactericidal</p> Signup and view all the answers

    What is the main reason why beta-lactams are not effective against atypical intracellular organisms?

    <p>They are not able to inhibit cell wall synthesis because atypical intracellular organisms lack a cell wall</p> Signup and view all the answers

    What type of infections is Penicillin G or V commonly used to treat?

    <p>Strep throat and Syphilis</p> Signup and view all the answers

    Which of the following bacteria is universally sensitive to Penicillin?

    <p>Group A Strep</p> Signup and view all the answers

    What is the primary indication for using Penicillin G or V in pregnant women?

    <p>Syphilis treatment</p> Signup and view all the answers

    Which of the following is NOT a typical spectrum of activity for Penicillin G or V?

    <p>Most strains of Gram-negative bacteria</p> Signup and view all the answers

    What type of infections may require desensitization to Penicillin in some cases?

    <p>Neurosyphilis or pregnant women</p> Signup and view all the answers

    Study Notes

    Beta-Lactams

    • Beta-lactams include PCNs, Cephalosporins, Carbapenems, and Monobactam (Aztreonam)
    • They inhibit cell wall crosslinking by binding to Penicillin-binding proteins (PBPs) in the cell membrane, making them bactericidal

    Side Effects

    • Hypersensitivity reactions, including anaphylaxis
    • Rashes
    • Bone marrow suppression
    • Interstitial Nephritis
    • GI symptoms: nausea, diarrhea, and C. diff
    • Seizures (mainly with high doses in renal failure)

    Preferred Use

    • Beta-lactams are the preferred drug choice for most situations due to high efficacy and cidal nature, as long as the pathogen is susceptible and the patient is not allergic

    Pharmacokinetics

    • Most oral beta-lactams have poor bioavailability and achieve low serum concentrations, making them poor choices for serious or deep-seated infections
    • Amoxicillin has the best bioavailability among oral beta-lactams

    Limitations

    • No beta-lactam has activity against MRSA, except Ceftaroline
    • No beta-lactam has activity against atypical intracellular organisms (e.g., Legionella, Mycoplasma, Chlamydia)

    Pharmacodynamics

    • Beta-lactams exhibit time-dependent killing, meaning efficacy depends on the amount of time the drug concentration is above the MIC

    Inducible Resistance

    • SPICE-A organisms (Serratia, Pseudomonas/Providencia, Indole-positive Proteus, Citrobacter, Enterobacter, and Acinetobacter) have inducible, chromosomal beta-lactamases (AmpC) that may not be detected on initial susceptibility testing
    • These beta-lactamases can lead to resistance while on therapy to all beta-lactams except carbapenems
    • Cefepime and Piperacillin/Tazobactam can be used with caution as well

    Penicillins

    • Penicillin G is administered intravenously (IV), while Penicillin V is administered orally (PO)

    Spectrum of Activity

    • Effective against many strains of Streptococci, including Group A Strep (universally PCN sensitive)
    • Effective against a minority of Staphylococci (most are resistant)
    • Effective against some Enterococcus and most oral anaerobes
    • Effective against Syphilis (universally PCN sensitive)

    Indications

    • Treats Strep throat and other infections caused by Group A Strep
    • Treats Syphilis (must desensitize to PCN for neurosyphilis or pregnant women)
    • Treats bacteremia and endocarditis caused by PCN sensitive Streptococcus, Enterococcus, or Staph aureus

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    Description

    This quiz covers the characteristics and side effects of BETA-LACTAMS, a class of antibiotics that includes PCNs, Cephalosporins, Carbapenems, and Monobactam. It includes their mechanism of action and main adverse effects.

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