Bacteria and Viruses Flashcards
mechanisms of resistance by bacteria include:
3 mechanisms
- inactivation by beta-lactamase (penicillinases)
- modification of penicillin binding proteins
- impaired penetration to target PBPs
which 2 bacteria resist antibiotics by modifying PBPs
PBP = penicillin binding proteins
- methicillin-resistant Staphylococcus aureus (MRSA)
- penicillin-resistant Streptococcus pneumoniae (PRSP)
mechanism of action for:
cephalosporin
D-Ala-D-Ala analogs; bind to PBP and inhibit synthesis of transpeptidase
similar to penicillin
mechanism of resistance for:
cephalosporin
- inactivation by beta-lactamases
- modification of target PBPs
- decrease in drug permeability
similar to penicillin
mechanism of action for:
monobactam
monocyclic beta-lactam ring
mechanism of action for:
carbapenem
ex: imipenem
synthetic beta-lactam drug, structurally related to penicillin
resistant to most beta-lactamases, but susceptible to metallo-beta-lactamase
mechanism of action for:
beta-lactamase inhibitors
resemble beta-lactam drugs; inhibit beta-lactamases as a competitive inhibitor
mechanism of action for:
vancomycin
binds to D-Ala-D-Ala and causes steric hindrance, inhibiting peptidoglycan synthesis
lacks beta-lactam ring and does NOT bind to PBPs
gold standard of treatment for MRSA; not susceptible to beta-lactamases
mechanism of resistance for:
vancomycin
modification of the D-Ala-D-Ala binding site
terminal D-Ala is replaced by D-lactate
Ribosomal antibiotics
6 total
30S ribosome:
Aminoglycosides - bactericidal
Tetracyclines (doxycycline)
50S ribosome:
Streptogramins - bactericidal
Erythromycin (Macrolides)
Lincosamides (clindamycin)
Linezolid
buy AT 30, SELL at 50
mechanism of action for:
aminoglycosides
ex: gentamicin, neomycin
- bind to 30S subunit
- block formation of 70S initiation complex
- cause mRNA misreading
- inhibit protein synthesis irreversibly, bactericidal
mechanism of resistance for:
aminoglycosides
ex: gentamicin, neomycin
production of drug-inactivating group transferases: aminoglycoside acetyltransferase, adenyltransferase, phosphotransferase
mechanism of action for:
tetracyclines
ex: doxycycline
- bind to 30S subunit
- inhibit binding of aminoacyl-tRNA to mRNA ribosomal complex
- bacteriostatic
mechanism of resistance for:
tetracyclines
ex: doxycycline
- efflux of drugs by plasmid-coded efflux protein pump
- altered permeability to drug
- enzymatic inactivation of drug
mechanism of action for:
Clindamycin (Lincosamides)
- bind to 50S subunit
- prevent the ribosome from translocating down mRNA
mechanism of resistance for:
Clindamycin (Lincosamides)
- methylation of ribosomal receptor site
- production of drug inactivating enzymes
- reduced permeability to the drug
mechanism of action for:
sulfonamides
antifolate drug
- competitive inhibitor of dihydropteroate synthase (DHPS), competes with para-aminobenzoic acid (PABA)
folate synthesis
mechanism of resistance for:
sulfonamides
antifolate drug
- decrease in intracellular accumulation
- increase in production of PABA
- decrease in sensitivity of DHPS to the drugs
mechanism of action for:
trimethoprim
selective inhibitor of dihydrofolate reductase (DHFR)
mechanism of resistance for:
trimethoprim
decrease in sensitivity of dihydrofolate reductase (DHFR) to the drug
mechanism of action for:
fluoroquinolones
- inhibit prokaryotic topoisomerase II (DNA gyrase) and topoisomerase IV
- bactericidal
mechanism of resistance for:
fluoroquinolones
- decrease in intracellular accumulation
- chromosome-encoded mutation in DNA gyrase
- plasmid-mediated resistance
mechanism of resistance for:
macrolides, lincosamides (clindamycin), streptogramins
methylation
name the DNA viruses
7 total
HHAPPPPY:
* Herpes
* Hepadna
* Adeno
* Pox
* Papilloma
* Parvo
* Polyoma
the rest are RNA viruses!
