Antibiotics MOA and Resistance Mechs. Flashcards
(49 cards)
T or F: drugs that mess with the structure of bacteria are typically bacteriostatic
False
What are the most common drugs to form allergies?
-Penicillin
What is the preferred oral treatment for non-penicillinase producing streptococci?
-Penicillin V
Differentiate between
- Penicillin
- Monobactam
- Carbapenem
- Cephalosporins
- Vancomycin
Penicillin – Thiazole Ring
Monobactam –sulfonic acid
- gets it inside the cell wall
Carbapenem
- Replaces thiazole sulfur with carbon giving it MORE RESITANCE to ß-lactamases, better penetration and affinity for more PBP
Cephalosporins
- 6 membered ring to make it more stable
Vanco – inhibits d-ala d-ala binding by transpeptidases
What drugs bind the 30S RSU? Which bind 50S?
Buy AT 30, CELL at 50
A = Aminoglycosides
T = Tetracyclines
30S
C = Chloramphenicol E = Erthromycin (macrolides) L = Linezolid L = cLindomycin 50S
Why use muti-drug therapy?
- Treat polymicrobial infections
- Decrease emergence of resistance
- Descrease Dose-related toxicity
- Enhanced cell-kill
Why might tetracyclines and chloramphenicol antagonize bactericidal cell wall agents?
Cell wall agents require that the cell be dividing to be effective
Why might giving a ß-lactam antagonize an infection?
Some gram (-) bacilli possess inducible lactamases that will be induced by the presence of ß-lactams
Bactericidal Antibiotics
- Aminoglycosides*
- Fluroquinolones
- Nitrofurantion
- Sulfonamides with DHFR inhibitors
- Metronidazole
Bacteriostatic antibiotics
Protein synthesis inhibitors
Sulfonamides
What bacteria are often treated by combining Penicillins with aminoglycosides?
- Staphylococci
- Enterococci
- Streptococci
- P aeruginosa
4 methods by which antibiotic work
- Inhibition of Cell Wall Synthesis
- Inhibition of Protein Synthesis
- Inhibition of Folic acid biosynthetic paths
- Inhibition of DNA/RNA synth
MOA of ß-lactams
Bind Penicillin binding proteins (transpeptidase) which causes destruction of the bacterial cell wall gram (+) bacteria are really the only type of microbe affected by this
What are the protype penicillins?
Penicillin G and Penicillin V
What are the narrow spectrum penicillins?
Oxacillin and Nafcillin
What are the aminopenicillins?
Ampicllin and Amoxicillin
What are the broad spectrum penicillins?
Pipercillin
What are 2 examples of ß-lactamase inhibtors being combined with penicillins?
- Clavulanic acid with Amoxicillin
- Tazobactam with Piperacillin
What is a common structural characteristic of Broad Spectrum Penicillin?
- why are they called broad spectrum ?
- What are they usually administered with?
Broad spectrum because AMINO group added increases ability to cross lipid layer in gram (-) bacteria
Usually administered with ß-lactamase inhibitors (clavulanic acid, or Tazobactam)
What are narrow spectrum penicillins?
Have larger molecules on their side chain that confers steric hinderance and ß-lactamase can’t twist molecule into different stereoisomers
- these are narrow spectrum because bulky side groups limit the amount of different bacterias that can be targeted
What are the 3 major categories of ß-lactams?
- Penicillins
- Carbaenems
- Cephalosporins
General problem with aminoglycoside administration:
- affected organs?
Poorly absorbed in GI Tract so oral administration is not possible. In general intracellular concentrations are low except in proximal tubule of the kidney where they can accumulate and cause NEPHROTOXICITY
Drugs ending in –mycin or –micin typically have what general function?
- mycin = macrolides
- micin = aminoglycosides
- both inhibit protein synthesis
T or F: most protein synthesis inhibitors are bactericidal
False, they are bacteriostatic with the exception of aminoglycosides, and Synpristin/dalfopristin (streptogramins) that are bactericidal
