Antibiotics Flashcards
Cell wall synthesis inhibitors
peptidoglycans: beta-lactams and glycopeptides
Beta-lactam function
prevent cross-linking of aa’s, cidal
Beta-lactam classes
penICILLINS, CEPHalosporins, carbaPENEMs, monobactams (ONAM)
Beta-lactam resistance mechanims
alternative target, restriction to access of target site, antibiotic destruction
how to avoid antibiotic destruction
antibiotic with protease inhibitor
Cephalosporins features
1-3 Gram +, 4-5 Gram -
Carbapenems features
wide spectrum of activity, drugs of last resort
Beta lactams dont work against…
species without cell wall, very impenetrable walls, intracellular pathogens
Glycopeptides features
Gram + only bc its huge and cant get through gram - membrane, binds to actual peptides, bactericidal, ie: Vancomycin, teicoplanin
Components of vancomycin resistance
Encoded on plasmid, alter peptide target (key), lock and key mechanism no longer works, blocks crosslinking
Common cell membrane disruptors
Daptomycin, colistin (polymyxin B)
Features of daptomycin
cyclic lipoprotein, inserts into membrane causing lysis, gram + only (used against vanco–resistant), bacteriacidal, resistance: efflux, membrane alterations, modify cell membrane charge
Colistin, polymoxin B features
gram (-) only, binds to LPS, cell lysis, bactericidal, kept as “last line of defense”, rare resistance with LPS mods
Which types inhibit nucleic acid synthesis
sulfonamides, trimethoprim, fluoroquinolones, rifamycins
Sulphonamides features (DNA base synthesis)
sulfonamides: dihydroptefoate synthase inhibition, trimethoprim: dihydrofolate reductase inhibtion; often given together, bacteriostatic, resistance: efflux, point mutations, alternative enzymes
Fluoroquinolones features
broad spectrum (aerobic gram +/-); -FLOXACIN; inhibits bacterial DNA gyrase and topoisomerase, bactericidal, resistance: point mutations, cell wall permeability, efflux pumps
RNA synthesis inhibtor
RIFamycins = RNA synthesis; RIFampin
RIFampin features
Binds to DNA dependent RNA polymerase, blocks mRNA synthesis, bactericidal, resistance: very eary, mutations to alter RNA polymerase target
Protein synthesis inhibitors
50S: Chloramphenicol, macrolides (-mycin), lincosamides (-mycin), oxazoladinones (-zolid, cidal)
30S: aminoglycosides, tetracyclines
30S subunit antibiotic features
Aminoglycosides: -MICIN, -MYCIN, inhibit initiation complex, bactericidal, aerobic gram (-) rods
TetraCYCLINEs: doxyCYCLINE, blocks tRNA from acceptor site, bacteriostatic, gram +/-
what are nitroimidazoles
antibiotic that causes DNA breaks, anaeobic and some protozoans, bactericidal
50S subunit antibiotic features
Chloramphenicol: prevent elongation, gram +/-, aerobes anaerobes, intracellular; bacteriostatic: resistance: acetyltransferase
Macrolides: erythroMYCIN, azithromycin; interferes with elongation; gram + cocci, especially strep, bacteriostatic
Lincosamides: clindamycin, interferes with elongation, more active against anaerobes, poor penetration, bacteriostatic
Oxazolidinones: lindeZOLID, interferes with intiation of protein translation, cidal
what are oxazolidinones
lineZOLID, tedZOLID; binds to ribosome prevents formation of initiation complex, used against drug-resistant gram + cocci (MRSA), can be bactericidal/static,
what is nitrofurantoin
antibiotic that is converted by bacterial enzymes to electrophilic intermediates which inhibits many processes, gram -/+; bacteriostatic; resistance is almost impossible
What is prophylaxis
antimicrobial agents used to prevent infection
