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Questions and Answers
What is the result of modifying the R2 side chain of the third-generation cephalosporins?
What is a characteristic of cefepime in regards to gram-negative β-lactamases?
What is a limitation of cefepime?
What is a unique property of cefepime compared to third-generation cephalosporins?
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What is the group at R1 that remains unchanged in the development of fourth-generation cephalosporins?
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What is a characteristic of cefepime's interaction with PBPs?
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What is the mechanism of action of cephalosporins?
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Which generation of cephalosporins has strong activity against aerobic gram-positive bacteria?
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What is a characteristic of first-generation cephalosporins?
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What is a characteristic of second-generation cephalosporins?
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Which generation of cephalosporins is most useful in the treatment of infections caused by aerobic gram-negative bacteria?
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Which class of antibiotics do cephalosporins belong to?
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What is a characteristic of third-generation cephalosporins?
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How are cephalosporins grouped?
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What is the type of group present at R1 in the structure of cefepime?
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What is the type of group present at R2 in the structure of cefepime?
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Which of the following bacteria is susceptible to fourth-generation cephalosporins?
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What is the activity of fourth-generation cephalosporins against Streptococcus pneumoniae?
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Which of the following is not a Gram-positive bacteria susceptible to fourth-generation cephalosporins?
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What is the activity of fourth-generation cephalosporins against Proteus spp.?
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Which of the following is a Gram-negative bacteria susceptible to fourth-generation cephalosporins?
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What is the activity of fourth-generation cephalosporins against Staphylococcus aureus?
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What is the functional group attached to the nitrogen atom in the structure of glycopeptides?
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What is the central atom in the PO3H2 group of the glycopeptide structure?
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Which of the following is a characteristic of the structure of telavancin?
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What is the functional group attached to the oxygen atom in the structure of glycopeptides?
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Which of the following glycopeptides has a decylaminoethyl side chain?
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What is the nitrogen-containing group in the structure of glycopeptides?
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What is the enzyme that hydrolyzes imipenem in the kidney?
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What is the primary activity of carbapenems?
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How does ertapenem compare to other carbapenems in terms of activity against aerobic gram-positive bacteria?
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What is the primary activity of aztreonam?
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What is the route of administration for aztreonam?
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What is a characteristic of monobactams?
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What is the primary mechanism of resistance to carbapenems in Pseudomonas aeruginosa?
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What is the purpose of co-administering cilastatin with imipenem?
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Study Notes
Cephalosporins
- Cephalosporins vary in their activities, with generations having distinct characteristics.
- Fourth-generation cephalosporins, such as cefepime, have enhanced activity against aerobic gram-negative bacteria, including Pseudomonas aeruginosa, and are relatively resistant to hydrolysis by gram-negative β-lactamases.
Structure of Cefepime
- Cefepime has a polar pyrrolidine group at R2, which allows for rapid penetration through the outer membrane of many gram-negative bacteria.
- The aminothiazolyl group at R1 is typical of many third-generation cephalosporins.
Antimicrobial Activity of Cefepime
- Cefepime has excellent activity against:
- Streptococcus pyogenes
- Viridans streptococci
- Many Streptococcus pneumoniae
- Escherichia coli
- Klebsiella pneumoniae
- Proteus spp.
- Modest activity against Staphylococcus aureus
- Limited anaerobic activity
Generalizations of Cephalosporin Generations
- First-generation cephalosporins have good activity against aerobic gram-positive bacteria.
- Second-generation cephalosporins have modest activity against aerobic gram-positive, aerobic gram-negative, and anaerobic bacteria.
- Third-generation cephalosporins have strong activity against aerobic gram-negative bacteria.
- Fourth-generation cephalosporins have especially enhanced activity against aerobic gram-negative bacteria.
- Fifth-generation cephalosporins have strong activity against aerobic gram-negative bacteria and excellent activity against aerobic gram-positive bacteria.
Carbapenems
- Carbapenems have excellent activity against aerobic gram-positive, aerobic gram-negative, and anaerobic bacteria.
- Imipenem is hydrolyzed by dehydropeptidase I in the kidney and must be given with cilastatin.
Monobactams
- Aztreonam, the only commercially available monobactam, is effective against aerobic gram-negative bacteria and is available for parenteral use only.
Glycopeptides
- The structure of glycopeptides, such as vancomycin and telavancin, is distinct from β-lactams.
- Telavancin has a lipophilic decylaminoethyl side chain, which is not present in vancomycin.
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Description
This quiz is about the modifications of cephalosporins, specifically the creation of fourth-generation cephalosporin cefepime. It discusses the changes made to the R2 side chain to improve antistaphylococcal activity.