Podcast
Questions and Answers
What is the primary mechanism of action of beta-lactam antibiotics?
What is the primary mechanism of action of beta-lactam antibiotics?
What is a common side effect of beta-lactam antibiotics?
What is a common side effect of beta-lactam antibiotics?
Which of the following beta-lactam antibiotics has activity against MRSA?
Which of the following beta-lactam antibiotics has activity against MRSA?
Why are oral beta-lactams often poor choices for serious or deep-seated infections?
Why are oral beta-lactams often poor choices for serious or deep-seated infections?
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What is the characteristic of beta-lactam antibiotics in terms of their killing mechanism?
What is the characteristic of beta-lactam antibiotics in terms of their killing mechanism?
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What is the name of the group of organisms that have inducible, chromosomal beta-lactamases and may lead to resistance to beta-lactams?
What is the name of the group of organisms that have inducible, chromosomal beta-lactamases and may lead to resistance to beta-lactams?
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Which of the following beta-lactam antibiotics is not affected by the inducible, chromosomal beta-lactamases of the SPICE-A organisms?
Which of the following beta-lactam antibiotics is not affected by the inducible, chromosomal beta-lactamases of the SPICE-A organisms?
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Why are beta-lactam antibiotics preferred in many situations?
Why are beta-lactam antibiotics preferred in many situations?
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What is the main reason why beta-lactams are not effective against atypical intracellular organisms?
What is the main reason why beta-lactams are not effective against atypical intracellular organisms?
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What type of infections is Penicillin G or V commonly used to treat?
What type of infections is Penicillin G or V commonly used to treat?
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Which of the following bacteria is universally sensitive to Penicillin?
Which of the following bacteria is universally sensitive to Penicillin?
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What is the primary indication for using Penicillin G or V in pregnant women?
What is the primary indication for using Penicillin G or V in pregnant women?
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Which of the following is NOT a typical spectrum of activity for Penicillin G or V?
Which of the following is NOT a typical spectrum of activity for Penicillin G or V?
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What type of infections may require desensitization to Penicillin in some cases?
What type of infections may require desensitization to Penicillin in some cases?
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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.
