Cell Wall Inhibitors: Glycopeptide Antibiotics

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Questions and Answers

What is the primary clinical use of vancomycin?

Treatment of uncomplicated skin infections

First-line treatment for complicated skin infections and bloodstream infections caused by MRSA (correct)

Prophylactic treatment for surgery

Treatment of viral infections

What is a potential side effect of vancomycin?

Increased appetite

Euphoria

Ototoxicity and nephrotoxicity (correct)

Muscle weakness

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

Inhibiting folate synthesis

Stopping the polymerization of NAM/NAG subunits (correct)

Inhibiting protein synthesis

Disrupting DNA replication

Which patient scenario might warrant the use of vancomycin in combination with gentamicin?

A patient with a serious penicillin allergy and enterococcal endocarditis Signup and view all the answers

What effect does the prolonged infusion of vancomycin have?

Prevents 'Red man' or 'red neck' syndrome Signup and view all the answers

To what issue is vancomycin resistance primarily attributed?

Plasmid-mediated changes in drug permeability or decreased binding to target molecules Signup and view all the answers

Which type of infections is vancomycin mainly restricted for, to reduce resistance?

Serious infections caused by beta-lactam resistant gram-positive organisms Signup and view all the answers

What is an uncommon reaction that may occur when vancomycin is administered with an aminoglycoside?

Ototoxicity Signup and view all the answers

What is the primary mechanism of action for Polymyxin B?

Disrupts cell membrane integrity Signup and view all the answers

Which of the following bacteria are primarily targeted by Polymyxin B?

Escherichia coli Signup and view all the answers

What side effects are associated with the use of Colistin?

Nephrotoxicity and neurotoxicity Signup and view all the answers

What aspect of Fosfomycin's action makes it suitable for urinary tract infections?

It maintains high concentrations in urine over several days Signup and view all the answers

The mechanism of Daptomycin primarily involves disrupting which cellular component?

Cell membrane Signup and view all the answers

Bacitracin is primarily indicated for which of the following applications?

Topical use for surface lesions Signup and view all the answers

What makes Daptomycin a preferred option for resistant bacterial infections?

It is effective against MRSA and VRE Signup and view all the answers

Which enzyme does Fosfomycin inhibit to block cell wall synthesis?

UDP-N-acetylglucosamine enolpyruvyl transferase Signup and view all the answers

Study Notes

Glycopeptide Antibiotics: Vancomycin

Effective against gram-positive bacteria, including MRSA and MRSE.
First-line treatment for complicated skin infections, bloodstream infections, endocarditis, bone and joint infections, and meningitis from MRSA.
Treats Clostridium difficile-induced pseudomembranous colitis when metronidazole fails.
Combined with gentamicin for enterococcal endocarditis in patients with severe penicillin allergies.
Used with cefotaxime, ceftriaxone, or rifampin for meningitis caused by penicillin-resistant pneumococcus.
Reserved for serious infections caused by β-lactam resistant, gram-positive microorganisms or in penicillin-allergic patients to prevent vancomycin resistance.

Mechanism and Resistance

Inhibits cell wall synthesis by stopping polymerization of NAM/NAG subunits through binding to D-Ala-D-Ala.
Resistance may occur due to plasmid-mediated changes affecting drug permeability or binding.

Adverse Reactions

Generally uncommon ototoxicity and nephrotoxicity; risk increases when administered with other ototoxic/nephrotoxic drugs.
Potential side effects include pain, thrombophlebitis, and "Red man syndrome" caused by histamine release; managed by prolonged infusion duration.

Polymyxin Antibiotics

Polymyxin B and colistin (polymyxin E) bind bacterial phospholipids in gram-negative bacteria, disrupting cell membrane integrity.
Effective against key gram-negative pathogens like Pseudomonas aeruginosa, E. coli, and Acinetobacter.
Notable for nephrotoxicity and neurotoxicity, with symptoms including slurred speech and muscle weakness.

Fosfomycin

Bactericidal agent that inhibits peptidoglycan synthesis by blocking the enzyme UDP-N-acetylglucosamine enolpyruvyl transferase.
Treats urinary tract infections caused by E. coli or E. faecalis; maintains effective urinary concentrations with a single dose.
Minimal cross-reactivity due to its unique structure; side effects may include diarrhea, headache, and nausea.

Daptomycin

Binds to cell membranes through a calcium-dependent mechanism, causing depolarization and ion leakage.
Inhibits protein, DNA, and RNA synthesis, leading to bacterial cell death.
Effective against resistant gram-positive organisms, including MRSA and vancomycin-resistant enterococci (VRE).

Bacitracin

Inhibits bacterial cell wall synthesis, specifically effective against gram-positive microorganisms.
Lacks cross-resistance with other antimicrobial agents.
Highly nephrotoxic when systemically administered; recommended for topical use on skin lesions and wounds only.

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Description

This quiz explores glycopeptide antibiotics, particularly vancomycin, and its clinical uses against gram-positive microbes, including MRSA. Test your knowledge on its efficacy in treating various complicated infections such as skin and bloodstream infections, endocarditis, and more.