Glycopeptide & Lipopeptide Antibiotics Flashcards
Vancomycin Spectrum
Spectrum: Staph, MRSA, Streptococci, Enterococci, Listeria, C-Diff
Vancomycin Mechanism
Mechanism: Forms a “cup” over the chain and blocks cross linking/enzyme reactions with the end of the peptidoglycan chain. Binds via 5-H bonds.
Vancomycin Resistance
Resistance: D-ala-D-ala changes to D-ala-D-lac. 5 genes confer resistance: 2 “sense” vanco and turn on other 3: 2 produce D-lac, last one destroys other D-ala-D-ala. 5-H bonds become 4 and resistance decreases 1,000 fold (this resistance takes longer to establish) ADR: “redneck syndrome” red rash from too rapid dosing
Telavancin
Type: Lipoglycopeptide Mechanism: similar to Vancomycin, “gloms” around pentapeptide to prevent cross-linking. hydrophilic tail “anchors” to bilayer. Drugs in this class: Oritivancin, Dalbavancin
Daptomycin
Type: Cyclic lipopeptide Spectrum: Gram+ (not used for pneumonia as surfactant binding inactivates daptomycin) Mechanism: Forms artificial pore through membrane, causing depolarization
Polymyxin B
Type: Polypeptide Spectrum: Gram- Mechansim: Doesn’t enter cell, disrupts plasma membrane (hence Gram- despite being big)
Colistin
Type: Polypeptide
Spectrum: Gram-.
Last ditch for pseudomonus a and acinetobacter. It’s hard on kidneys but beats being dead
Floroquinolones
Act intracellularly Inhibit DNA synthesis Inhibit DNA replication by interfering with topoisomerases (which remove DNA supercoils) Bactericidal Resistance: Mutations in DNA gyrase/Topoisomerase (easy to do)
Sulfonamides
Inhibit folic acid synthesis synergistically with trimethoprim
Rifampin
Inhibits DNA-Dependent RNA Polymerase
Metronidazole
Direct DNA damage. Introduces double strand breaks to DNA. Only works in low redox potential environments (anaerobic environments)
