Podcast
Questions and Answers
What is the mechanism of action for macrolides?
What is the mechanism of action for macrolides?
Which adverse effect is associated with lincosamides?
Which adverse effect is associated with lincosamides?
Which of the following tetracyclines is known for poor absorption?
Which of the following tetracyclines is known for poor absorption?
What is a key characteristic of azithromycin compared to erythromycin and clarithromycin?
What is a key characteristic of azithromycin compared to erythromycin and clarithromycin?
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Which of the following bacteria are tetracyclines mainly active against?
Which of the following bacteria are tetracyclines mainly active against?
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What is the main use of antipseudomonal penicillins?
What is the main use of antipseudomonal penicillins?
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Which of the following combinations includes a beta-lactamase inhibitor?
Which of the following combinations includes a beta-lactamase inhibitor?
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What is the mechanism of action for glycopeptides like Vancomycin?
What is the mechanism of action for glycopeptides like Vancomycin?
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What distinguishes the third generation cephalosporins from the first generation?
What distinguishes the third generation cephalosporins from the first generation?
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What is a notable adverse effect of Imipenem?
What is a notable adverse effect of Imipenem?
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Which of the following is true about monobactam Aztreonam?
Which of the following is true about monobactam Aztreonam?
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What class of antibiotics does Daptomycin belong to?
What class of antibiotics does Daptomycin belong to?
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Which statement is true regarding Rifamycins?
Which statement is true regarding Rifamycins?
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Which of the following is a common adverse effect of Vancomycin?
Which of the following is a common adverse effect of Vancomycin?
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What is the primary action of aminoglycosides?
What is the primary action of aminoglycosides?
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What is the mechanism of action of nitroimidazoles?
What is the mechanism of action of nitroimidazoles?
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Which of the following describes the effect of oxazolidinones on bacteria?
Which of the following describes the effect of oxazolidinones on bacteria?
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Which adverse effect is particularly associated with linezolid?
Which adverse effect is particularly associated with linezolid?
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Which fluoroquinolone is not effective against gram-positive bacteria?
Which fluoroquinolone is not effective against gram-positive bacteria?
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What type of bacteria exhibit common resistance to fluoroquinolones?
What type of bacteria exhibit common resistance to fluoroquinolones?
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What is a significant adverse effect associated with fluoroquinolones?
What is a significant adverse effect associated with fluoroquinolones?
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Which statement regarding the renal elimination of fluoroquinolones is accurate?
Which statement regarding the renal elimination of fluoroquinolones is accurate?
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What should be considered when administering linezolid to a patient taking antidepressants?
What should be considered when administering linezolid to a patient taking antidepressants?
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Study Notes
Penicillins
- Ureidopenicillin (no longer available as a single agent) penetrates the cell wall of pseudomonas, unlike aminoampicillin.
- Antipseudomonal penicillins have an additional adverse effect: thrombocytopenia.
- They are susceptible to beta lactamases.
- They are mainly used in combination with tazobactam.
Penicillin Drug Development
- Penicillins have been developed with modifications over time, including natural PCNs, anti-staph PCNs, aminopenicillins, antipseudomonal PCNs, and penicillin/beta-lactamase inhibitor combinations.
Penicillin/Beta-Lactamase Inhibitor Combinations
- These combinations include piperacillin/tazobactam (Zosyn®), ampicillin/sulbactam (Unasyn®), and amoxicillin/clavulanate (Augmentin®).
- They provide better coverage for gram-negative rods compared to the parent drugs alone.
- They are used for infections caused by streptococci, MSSA, enterococci, anaerobes, and GI infections.
- They don't cover Pseudomonas.
- Susceptibility to one antistaphylococcal beta-lactam indicates susceptibility to all.
- These combinations are used empirically because they provide good nosocomial coverage.
1st generation cephalosporin
- Includes cefalozin, cephalaxin, and cefadroxil.
- Eliminated renally.
- Useful for treating MSSA, streptococci, and gram-negative rods.
2nd generation cephalosporin
- Includes cefuroximine, cefoxitin (anaerobic activity), and cefotaten (anaerobic activity),
3rd generation cephalosporin activity
- Decreased antistaph activity.
- Improved antistrep activity compared to previous generation.
4th generation cephalosporin activity
- Includes cefepime, cefimine, and cefopodoimine.
- Eliminated renally.
- May have different activity than previous generations.
Anti-MRSA Cephalosporin
- Useful for treating MRSA and MSSA, strep, and gram-negative rods.
- Not effective against Pseudomonas.
- Susceptible to beta lactamase.
Cephalosporin/beta-lactamase Inhibitor Combinations
- Provide broader coverage, including against Pseudomonas aeruginosa and Klebsiella pneumonia.
Carbapenems
- Includes imipenum/cilastin, meropenum, and ertapenum.
- Renally eliminated.
- Imipenum has a higher risk of seizures compared to other carbapenems.
Monobactam
- Aztreonam is the only monobactam.
- Active against GNR, including Pseudomonas.
- Renally eliminated.
- Not cross-reactive with other beta-lactam allergies, except ceftazidime and cefiderocol.
- Used for gram-negative infections in patients with allergies to other beta-lactams.
Carbapenem/Beta-lactamase Inhibitor Combinations
- Includes meropenem-vaborbactam and imipenem- (cilastatin)-relebactam.
- Possess the same activity as their respective carbapenem counterparts.
Glycopeptides
- Vancomycin is the most well-known glycopeptide.
- Inhibits cell wall synthesis by binding to the terminal of the D-ala-D-ala chain of peptidoglycan.
- Poor bioavailability and widely distributed throughout the body.
- Eliminated renally.
- Effective against gram-positive aerobes and anaerobes, including MRSA.
- Does not kill beta-lactam-susceptible staphylococci as quickly as beta-lactams.
- Used primarily for MRSA infections when beta-lactams are not an option.
- Beta-lactams are generally more effective at killing MSSA than glycopeptides.
- Adverse effects include vancomycin infusion syndrome (not an allergy), red man syndrome, nephrotoxicity, and ototoxicity.
- Used for MRSA and gram-positive infections with severe beta-lactam allergies.
Lipoglycopeptide(s)
- Includes telavancin (used for skin/skin infections and pneumonia from gram-positive structures), oritavancin (used for skin/skin infections), and dalbavancin (used for the same indications as oritavancin).
Fosfomycin
- Inhibits monomer production.
- Bactericidal and renally eliminated.
- Moderately bioavailable.
- Active against Pseudomonas, staph, and enterococci.
Cyclic Lipopeptide
- Daptomycin is the only cyclic lipopeptide.
- Inserts into the cell membrane of gram-positive organisms, leading to cation leak, depolarization, and cell death.
- Bactericidal, poorly absorbed, and inactive in the lung.
- Excreted renally.
- Active against gram-positive aerobes and anaerobes, including MRSA and VRE.
Rifamycins
- Includes rifampin, rifabutin, rifapentine, and rifaximin.
- Blocks transcription.
- Bactericidal and active against a broad spectrum of gram-positive and gram-negative bacteria, including mycobacteria.
- Strong inducers of CYP450, an enzyme system that metabolizes many drugs.
- Adverse effects include rash, hypersensitivity, and hepatotoxicity.
- Discolors secretions orange-red.
- Rifapentine has an extended half-life.
- Rifaximin is not absorbed.
Aminoglycosides
- Includes gentamicin, tobramycin, amikacin, neomycin, streptomycin, and plazomicin.
- Inhibit translation by binding to 16S rRNA of the 30S ribosomal subunit, causing misreading and leading to cell death.
- Bactericidal, have low bioavailability, and are eliminated renally.
- Short half-lives and exhibit excellent activity against a broad range of bacteria.
Macrolides
- Includes erythromycin, clarithromycin, and azithromycin.
- Inhibit translation by binding to 23s rRNA of the 50S subunit of the ribosome.
- Bacteriostatic and achieve high intracellular concentrations.
- Highly bioavailable.
- Erythromycin and Clarithromycin are inhibitors of the CYP 450 system, leading to potential drug interactions.
- Azithromycin has almost no interaction potential.
- Resistance is often due to efflux pumps.
- Used for pneumonia and upper respiratory tract infections.
Lincosamides
- Includes clindamycin and lincomycin.
- Inhibit translation by binding to the 50S subunit of bacterial ribosomes.
- Bacteriostatic.
- Active against staphylococci (including some MRSA) and streptococci, but not C.difficile.
- Adverse effects include C.difficile infection, diarrhea, abdominal pain, nausea, and rash.
- Main uses include skin and soft tissue infections, anaerobic infections, and acne (topical).
- Resistance is often due to an altered target site.
- Some coverage against GNR.
Tetracycline
- Includes minocycline and doxycycline.
- Inhibit translation by reversibly binding to 16S rRNA of the 30S ribosomal subunit, blocking tRNA from binding.
- Bacteriostatic.
- Active against staphylococci (including MRSA) and some strep.
Other Tetracyclines
- Includes tigecycline, eravacycline, and omadacycline.
- Modified tetracyclines that have an expanded spectrum of activity.
- Poor absorption (omadacyline-moderate).
- Very high distribution-low plasma concentrations.
- Long half-life and mostly eliminated hepatically.
- Cover many GNR and GPC, including VRE and MRSA.
- Good anaerobic coverage, but do not cover Pseudomonas or Proteus species.
- Tigecycline has significant adverse effects.
Nitroimidazoles
- Includes metronidazole and tinidazole.
- Interacts with DNA, leading to loss in DNA structure and strand breakage.
- Bactericidal.
Oxalidinones
- Includes linezolid and tedizolid.
- Inhibit protein synthesis by binding to 23S rRNA of the 50S subunit.
- Bacteriostatic.
- Highly bioavailable.
- Linezolid is dual eliminated via hepatic metabolism and renal excretion.
- Tedizolid is eliminated hepatically.
- Linezolid is a weak, reversible inhibitor of monoamine oxidase.
- Use with caution when taking antidepressants.
- Active against gram-positive aerobes, including MRSA, streptococci, and enterococci, including VRE.
- Adverse effects include serotonin syndrome with some drugs, bone marrow suppression, particularly thrombocytopenia.
Fluoroquinolones
- Includes ofloxacin, ciprofloxacin, levofloxacin, moxifloxacin, and others.
- Inhibit DNA replication by binding to DNA gyrase (topo II) or topoisomerase IV.
- Bactericidal and highly bioavailable.
- Respiratory FQs (levofloxacin, moxifloxacin, gemifloxacin, delafloxacin, and gatifloxacin) are active against S. pneumoniae.
- Ciprofloxacin is used for pneumonia caused by GNR.
- Primarily renally excreted, except moxifloxacin (hepatic) and gemifloxacin (dual).
- Activity varies between drugs.
- Active against enterobacterales and atypical organisms.
- Ciprofloxacin, levofloxacin, and delafloxacin are active against P. aeruginosa.
- Ciprofloxacin has poor gram-positive activity.
- Treatment failures can occur with streptococci and staphylococci.
- Resistance is common in P. aeruginosa and S. aureus, uncommon in streptococci, and very high in E. coli in some areas.
- Adverse effects include a lower seizure threshold, N/V/D, photosensitivity, arthropathy, QTc prolongation, and mental status changes in the elderly.
- Absorption is reduced drastically with concomitant multivalent cations.
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Description
Explore the evolution and characteristics of penicillins, including their various forms and combinations. This quiz covers their development, effectiveness against specific bacteria, and the challenges posed by beta-lactamases. Test your knowledge on key concepts surrounding penicillins and their applications in clinical settings.
