Podcast
Questions and Answers
What is the result of modifying the R2 side chain of the third-generation cephalosporins?
What is the result of modifying the R2 side chain of the third-generation cephalosporins?
- Loss of anaerobic activity
- Loss of antistaphylococcal activity
- Gain of antipseudomonal activity (correct)
- Increase in gram-positive activity
What is a characteristic of cefepime in regards to gram-negative β-lactamases?
What is a characteristic of cefepime in regards to gram-negative β-lactamases?
- It only affects chromosomally encoded inducible AmpC β-lactamases
- It has no effect on gram-negative β-lactamases
- It is resistant to hydrolysis (correct)
- It is highly susceptible to hydrolysis
What is a limitation of cefepime?
What is a limitation of cefepime?
- It is highly susceptible to hydrolysis by gram-negative β-lactamases
- It is only effective against P. aeruginosa
- It has no activity against aerobic gram-positive cocci
- It has very limited anaerobic activity (correct)
What is a unique property of cefepime compared to third-generation cephalosporins?
What is a unique property of cefepime compared to third-generation cephalosporins?
What is the group at R1 that remains unchanged in the development of fourth-generation cephalosporins?
What is the group at R1 that remains unchanged in the development of fourth-generation cephalosporins?
What is a characteristic of cefepime's interaction with PBPs?
What is a characteristic of cefepime's interaction with PBPs?
What is the mechanism of action of cephalosporins?
What is the mechanism of action of cephalosporins?
Which generation of cephalosporins has strong activity against aerobic gram-positive bacteria?
Which generation of cephalosporins has strong activity against aerobic gram-positive bacteria?
What is a characteristic of first-generation cephalosporins?
What is a characteristic of first-generation cephalosporins?
What is a characteristic of second-generation cephalosporins?
What is a characteristic of second-generation cephalosporins?
Which generation of cephalosporins is most useful in the treatment of infections caused by aerobic gram-negative bacteria?
Which generation of cephalosporins is most useful in the treatment of infections caused by aerobic gram-negative bacteria?
Which class of antibiotics do cephalosporins belong to?
Which class of antibiotics do cephalosporins belong to?
What is a characteristic of third-generation cephalosporins?
What is a characteristic of third-generation cephalosporins?
How are cephalosporins grouped?
How are cephalosporins grouped?
What is the type of group present at R1 in the structure of cefepime?
What is the type of group present at R1 in the structure of cefepime?
What is the type of group present at R2 in the structure of cefepime?
What is the type of group present at R2 in the structure of cefepime?
Which of the following bacteria is susceptible to fourth-generation cephalosporins?
Which of the following bacteria is susceptible to fourth-generation cephalosporins?
What is the activity of fourth-generation cephalosporins against Streptococcus pneumoniae?
What is the activity of fourth-generation cephalosporins against Streptococcus pneumoniae?
Which of the following is not a Gram-positive bacteria susceptible to fourth-generation cephalosporins?
Which of the following is not a Gram-positive bacteria susceptible to fourth-generation cephalosporins?
What is the activity of fourth-generation cephalosporins against Proteus spp.?
What is the activity of fourth-generation cephalosporins against Proteus spp.?
Which of the following is a Gram-negative bacteria susceptible to fourth-generation cephalosporins?
Which of the following is a Gram-negative bacteria susceptible to fourth-generation cephalosporins?
What is the activity of fourth-generation cephalosporins against Staphylococcus aureus?
What is the activity of fourth-generation cephalosporins against Staphylococcus aureus?
What is the functional group attached to the nitrogen atom in the structure of glycopeptides?
What is the functional group attached to the nitrogen atom in the structure of glycopeptides?
What is the central atom in the PO3H2 group of the glycopeptide structure?
What is the central atom in the PO3H2 group of the glycopeptide structure?
Which of the following is a characteristic of the structure of telavancin?
Which of the following is a characteristic of the structure of telavancin?
What is the functional group attached to the oxygen atom in the structure of glycopeptides?
What is the functional group attached to the oxygen atom in the structure of glycopeptides?
Which of the following glycopeptides has a decylaminoethyl side chain?
Which of the following glycopeptides has a decylaminoethyl side chain?
What is the nitrogen-containing group in the structure of glycopeptides?
What is the nitrogen-containing group in the structure of glycopeptides?
What is the enzyme that hydrolyzes imipenem in the kidney?
What is the enzyme that hydrolyzes imipenem in the kidney?
What is the primary activity of carbapenems?
What is the primary activity of carbapenems?
How does ertapenem compare to other carbapenems in terms of activity against aerobic gram-positive bacteria?
How does ertapenem compare to other carbapenems in terms of activity against aerobic gram-positive bacteria?
What is the primary activity of aztreonam?
What is the primary activity of aztreonam?
What is the route of administration for aztreonam?
What is the route of administration for aztreonam?
What is a characteristic of monobactams?
What is a characteristic of monobactams?
What is the primary mechanism of resistance to carbapenems in Pseudomonas aeruginosa?
What is the primary mechanism of resistance to carbapenems in Pseudomonas aeruginosa?
What is the purpose of co-administering cilastatin with imipenem?
What is the purpose of co-administering cilastatin with imipenem?
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.
