Antimicrobial Agents Flashcards
Beta-Lactam Drugs
MOA • inhibition of enzymes (transpeptidase) needed for peptidoglycan formation • formation of covalent complexes with enzymes
Penicllins
MOA • binds to enzyme penicillin binding protein (transpeptidase) • to mediate transpeptidation reaction
Cephalosporins
•can withstand the action of beta-lactamases •more modifiable •structurally similar to penicillin
Glycopeptides
MOA • binds to terminal D-Ala-D-Ala of the pentapeptide-glycosyl peptidoglycan intermediates • binds to substrate (D-Ala, D-Ala)
Glycopeptides
• interferes with cross-linking in peptidoglycan
Cycloserine
MOA • inhibits synthesis of peptidoglycan precursors (D-Ala D-Ala) in the cytoplasm
Bacitracin
MOA • inhibits transport of lipid-bound precursors across the cytoplasmic membrane
Bacitracin
MOA • inhibits NAG and NAM synthesis
Polymyxins
MOA • acts like detergents which interact with phospholipids
Polymyxins
MOA • increases permeability and macromolecule leakage
Folate
important DNA synthesis precursor
Sulfonamides
MOA • competitive inhibition of folic acid synthesis • binds to dihydropteroate synthase
Trimethoprim
MOA • blocks steps of tetrahydrofolase formation by dihydrofolate reductase prevention
Trimethoprim
MOA • targets the folic acid pathway
Fluoroquinolones
MOA • binds and interferes with DNA gyrase (for Gr -) and topoisomerase IV (for Gr +)
Metronidazole
MOA • Nitro group is reduced by nitroreductase • responsible for DNA breakage due to chemical action
Rifamycin
MOA • binds to DNA dependent RNA polymerase
Chloramphenicol
MOA • inhibits translation through elongation step inhibition
Macrolides
MOA • inhibits tRNA (transfer RNA) • inhibits translation by elongation inhibition through 23S RNA binding
Oxazolidinones
MOA • inhibits initiation of mRNA translocation • inhibits protein synthesis by interacting with 23S RNA
Tetracyclines and Doxycycline
MOA • inhibits protein synthesis by binding reversibly to the 30S ribosomal subunit
Tetracycline and Doxycycline
targets intracellular pathogens
Aminoglycosides
used with penicillins in order to diffuse and enter bacterial cell
1st Line Drugs
Isoniazid Less side effects Pyrazinamide Rifampicin
2nd Line Drugs
Streptomycin Ethambutol TB treatment (1st line resistant)
Inhibition of Cell Wall Synthesis
Beta-Lactams Cycloserine Bacitracin
Inhibition of Cell Membrane Function
Polymyxins
Inhibitors of Folate Synthesis
Sulfonamides Trimethoprim
Interference with DNA synthesis
Fluroquinolones Metronidazole
Interference with RNA synthesis
Rifamycins
Inhibition of Protein Synthesis 30S ribosome inhibition
Chloramphenicol Macrolides Oxazolidinones
Inhibition of Protein Synthesis 30S ribosome inhibition
Tetracyclines Doxycyclines Aminoglycoside
Streptomycin
Gentamycin
Tobramycin
Amikacin
Neomycin
Give aminoglycosides examples.
(Hint: There are five.)
Biological resistance
changes that results in observably reduced susceptibility of organism to a particular antimicrobial agent
Clinical resistance
antimicrobial susceptibility has been lost
Intrinsic/inherent
resistance is predictable
Acquired
resistance is unpredictable
mefA
Give the gene.
Streptococcus pneumoniae
msrA
Staphylococcus aureus & Enterococcus
mreA
Streptococcus agalactiae
Lateral Gene Transfer
most important strategy of bacteria to spread resistance