Pharmacology II: Cell Wall Inhibitors II

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Questions and Answers

Which generation of cephalosporins is effective against MRSA?

4th generation (correct)

2nd generation

1st generation

3rd generation

First-generation cephalosporins are ineffective against MSSA.

False

Name one third-generation cephalosporin.

Cefotaxime

Ceftriaxone is an agent of choice for meningitis caused by ________.

pneumococci Signup and view all the answers

Which of the following is NOT effective against Clostridium difficile?

All cephalosporins Signup and view all the answers

Match the cephalosporins with their characteristics:

Cefazolin = 1st-generation Cefuroxime = 2nd-generation Ceftazidime = 3rd-generation with activity against P. aeruginosa Ceftaroline = 4th-generation effective against MRSA Signup and view all the answers

Cefepime is effective against aerobic gram-negative organisms.

True Signup and view all the answers

What is a significant drawback of third-generation cephalosporins?

Collateral damage Signup and view all the answers

Which of the following is NOT an adverse effect associated with cephalosporins?

Eosinophilia Signup and view all the answers

Carbapenems are effective against anaerobes.

True Signup and view all the answers

Name one cephalosporin that possesses cross-sensitivity with penicillin.

1st generation cephalosporins Signup and view all the answers

Monobactams, such as _____, have a β-lactam ring that is not fused to another ring.

Aztreonam Signup and view all the answers

Match the antibiotic class with its characteristic:

Cephalosporins = Resistance to β-lactamases Carbapenems = Broad-spectrum efficacy Monobactams = Lacks activity against gram-positive organisms Penicillins = Common cross-sensitivity with cephalosporins Signup and view all the answers

Which drug is known for causing seizures at high levels?

Imipenem Signup and view all the answers

Aztreonam has high cross-reactivity with other β-lactams, making it unsafe for allergic patients.

False Signup and view all the answers

What is the primary indication for the use of carbapenems?

Empiric therapy against β-lactamase producing organisms Signup and view all the answers

Study Notes

Cephalosporins Overview

Cephalosporins share the same mechanism of action (MOA) as penicillins and have a similar resistance profile.
They are more stable against bacterial lactamases but ineffective against MRSA, L.monocytogenes, Clostridium difficile, and enterococci.

First-Generation Cephalosporins

Examples include cefazolin, cephalexin, and cefadroxil.
Effective against MSSA due to resistance to staphylococcal penicillinase.

Second-Generation Cephalosporins

Includes cefuroxime, cefotetan, cefoxitin, cefprozil, and cefaclor.
Less potent against MSSA compared to first generation, but effective against gram-negative bacilli and enteric organisms.

Third-Generation Cephalosporins

Agents include cefotaxime, ceftriaxone, and ceftazidime.
More active against gram-negative pathogens; recommended for meningitis caused by pneumococci and meningococci, but not effective against L.monocytogenes.
Ceftazidime has activity against Pseudomonas aeruginosa, though resistance is a growing concern.
Associated with collateral damage affecting microbial flora.

Fourth-Generation Cephalosporins

Cefepime is widely effective against methicillin-susceptible staphylococci and aerobic gram-negative organisms.
Advanced generation cephalosporins like ceftaroline are effective against MRSA and used for complicated skin infections and community-acquired pneumonia.

Resistance and Side Effects of Cephalosporins

Susceptible to extended-spectrum β-lactamases (ESBLs) from E.coli and K.pneumoniae.
Potential adverse effects include hypersensitivity reactions, nephritis, skin rashes, and hematological issues.
Cross-sensitivity exists between penicillins and first-generation cephalosporins.

Carbapenems

Includes imipenem, meropenem, doripenem, and ertapenem, functioning as synthetic β-lactam antibiotics.
Effective against a wide variety of bacteria including anaerobes and resistant gram-negative organisms like P.aeruginosa.
Imipenem is often used for empirical therapy due to its robust activity.

Pharmacokinetics and Adverse Effects of Carbapenems

Imipenem/cilastatin and meropenem penetrate well into body tissues, achieving therapeutic levels in conditions like bacterial meningitis.
Adverse effects include gastrointestinal disturbances, eosinophilia, neutropenia, and potential seizures with high imipenem dosage.

Monobactams

Aztreonam is the primary agent, featuring a unique β-lactam ring structure.
Targets gram-negative bacteria, including Enterobacteriaceae and P.aeruginosa, with no effectiveness against gram-positive bacteria or anaerobes.
Exhibits low toxicity, but can cause phlebitis, skin rash, and liver function abnormalities.
Minimal cross-reactivity makes it a suitable alternative for patients allergic to other β-lactams.

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Description

This quiz covers the topic of cell wall inhibitors, specifically focusing on cephalosporins. Students will learn about their mechanism of action, resistance mechanisms, and limitations against certain bacteria. Ideal for students in pharmacology courses within veterinary medicine.