Cephalosporins Overview

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Questions and Answers

What condition is oral vancomycin primarily used to treat?

Bacterial infections in patients allergic to penicillin

Serious skin infections caused by gram-positive organisms

Potentially life-threatening antibiotic-associated colitis due to C. difficile (correct)

Bloodstream infections caused by resistant bacteria

Which of the following statements about vancomycin is correct?

Vancomycin can be safely administered at any rate intravenously.

The drug can be absorbed efficiently from the gastrointestinal tract.

It is the first-line treatment for all gram-positive infections.

Vancomycin should not be used for infections caused by resistant gram-negative organisms. (correct)

What is a common side effect of rapid infusion of vancomycin?

Superinfection

Nephrotoxicity

Ototoxicity

Red-man syndrome (correct)

Which of the following combinations enhances vancomycin's effectiveness?

Vancomycin and aminoglycosides Signup and view all the answers

What is the major route of excretion for vancomycin?

Kidneys Signup and view all the answers

Which carbapenem is known for having a wide activity against Gram-positive, Gram-negative, and anaerobic bacteria?

Meropenem Signup and view all the answers

What is the primary concern regarding the use of vancomycin?

Emergence of resistance Signup and view all the answers

Which of the following is a characteristic of Aztreonam?

Only works on G- infections Signup and view all the answers

What mechanism does vancomycin use to inhibit bacterial cell wall synthesis?

Inhibits transglycosylation Signup and view all the answers

What is a common side effect of carbapenem antibiotics?

Nausea and vomiting Signup and view all the answers

What makes bacitracin's application limited compared to other cell wall synthesis inhibitors?

Toxicity in systemic use Signup and view all the answers

Which type of infections are carbapenems considered the drugs of choice for?

Infections caused by Enterobacter Signup and view all the answers

Which of the following is NOT a known toxicity related to carbapenems?

Severe arrhythmias Signup and view all the answers

Which generation of cephalosporins is characterized by excellent activity against susceptible staph and strep?

First Generation Signup and view all the answers

What is a primary characteristic of the fourth generation cephalosporin, Cefepime?

It has the same antimicrobial spectrum as third generation but resists more beta-lactamases. Signup and view all the answers

Which of the following is NOT typically treated with second generation cephalosporins?

Bacterial meningitis Signup and view all the answers

What type of infections are third generation cephalosporins particularly effective against?

Serious G- infections Signup and view all the answers

Cefazolin is commonly administered through which route?

Intravenous Signup and view all the answers

What adverse effect is associated with methylthiotetrazole-containing cephalosporins?

Hypoprothrombinemia Signup and view all the answers

Which cephalosporin generation shows increased activity against Gram-negative bacteria?

Second Generation Signup and view all the answers

What mechanism of action do cephalosporins share with penicillins?

Inhibition of cell wall synthesis Signup and view all the answers

Study Notes

Cephalosporins

Cephalosporins are cell wall synthesis inhibitors.
Different generations of cephalosporins have varying spectra of activity and pharmacological properties.
The mechanism of action and resistance, as well as the broader pharmacology, are similar to penicillins.
First-generation cephalosporins are effective against susceptible staphylococci and streptococci, and have modest activity against gram-negative bacteria. They are generally given intravenously (IV) or intramuscularly (IM). They are excreted by the kidneys, unmetabolized.
Second-generation cephalosporins exhibit modest activity against gram-positive bacteria and increased activity against gram-negative bacteria and anaerobes. Absorption and excretion profiles are similar to first-generation.
Third-generation cephalosporins have a broad spectrum, and are often the drugs of choice for serious infections, especially those caused by gram-negative bacteria. Cefpodoxime and cefixime are oral, while others are administered parentally.
Fourth generation cephalosporins, like cefepime, have similar activity to third generation but resist more beta-lactamases. They are administered parentally and have excellent penetration into the cerebrospinal fluid (CSF).
Fifth-generation cephalosporins, such as cetobiprole, are generally effective against a wider array of resistant organisms.

Toxicity/Contraindications

Hypersensitivity reactions to cephalosporins are similar to those seen with penicillins, although uncommon.
Cross-reactions can occur between cephalosporins and penicillins.
Common side effects such as nausea and vomiting may occur.
Pain at the injection site, and phlebitis after IV administration are side effects.
Some cephalosporins (containing methylthiotetrazole), can cause hypoprothrombinemia and disulfiram-like reactions.
When administered with aminoglycosides, they may increase nephrotoxicity.

Carbapenems (Imipenem, Meropenem, Ertapenem)

Carbapenems, like imipenem, are similar to penicillins in their effect on microbes and their pharmacology, but have a broader spectrum of activity against gram-positive, gram-negative and anaerobic bacteria.
Useful in treating pseudomonal infections where they're often administered with aminoglycosides.
Usually administered parenterally.
They are often the drugs of choice for infections caused by Enterobacter.

Monobactam (Aztreonam)

Specifically active against gram-negative bacteria, including Pseudomonas.
Useful for treating G- infections where a beta-lactam is needed but hypersensitivity reactions are a concern.

Cell Wall Synthesis Inhibitors (Non-β-Lactams)

Vancomycin
- A tricyclic glycopeptide
- Effective against multiple drug-resistant organisms such as MRSA and enterococci
- Concerns exist about the emergence of vancomycin resistance.
- Mode of action: Inhibits peptidoglycan polymerization by binding to the D-Ala-D-Ala side chain of the precursor pentapeptide. It also affects transglycosylation steps of peptidoglycan, weakening the cell wall.
Daptomycin
Teicoplanin
Telvancin
Bacitracin

Pharmacokinetics of Vancomycin

Usually administered intravenously (IV) over an hour.
Can be administered orally for pseudomembranous colitis.
30% of the drug binds to serum proteins.
Appears in various bodily fluids, including the CSF.
Excretion is via the kidneys.

Toxicity/Contraindications of Vancomycin

Red Man Syndrome (erythematous or urticarial reaction) is a common side effect when given quickly.
Ototoxicity and nephrotoxicity are less common but can occur to higher doses.

Other Vancomycin Inhibitors

Treatments for vancomycin-resistant organisms
Daptomycin
Quinopristin/dalfopristin
Linezolid
Synergistic use with aminoglycosides in enterococcal endocarditis treatment

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Description

This quiz covers the different generations of cephalosporins, their mechanism of action, and pharmacological properties. It discusses the spectrum of activity for first, second, and third-generation cephalosporins, including their efficacy against gram-positive and gram-negative bacteria. Test your knowledge on this important class of antibiotics.