Antibacterials Flashcards
Penicillin mechanism and usage
Bind to PBPs (aka transpeptidases) and block peptidoglycan cross linking in the cell wall of bacteria.
Used for gram positives and N.meningitides and T. pallidum.
Bactericidal
Ampicillin, amoxiillin mechanism
Aminopenicillins bind to PBP and prevent cross linking of peptidoglycans. Also penicillinase sensitive.
Combine with clavulanic acid to protect against beta lactamases.
Aminopenicillin usage
Extended spectrum penicillin, includes haemophilus, e.coli, listeria, proteus, salmonella, shigella.
Aminopenicillin toxicity
hypersensitivity reactions, rash, pseudomembranous colitis.
Oxacillin, nafcillin, dicloxacillin mechanism and usage
Side effect?
Blocks transpeptidases (PBP) from cross linking peptidoglycans on cell wall. These are penicillinase resistant because of a bulky R group.
Used for S.aureus.
Cause interstitial nephritis!!!!!
Ticarcillin,piperacillin mechanism/usage.
Block PBP and cross linking of peptidoglycans. Used for pseudomonas and other gram negative rods. Best combined with beta lactamase inhibitors.
Beta lactamase inhibitors
Clavulanic acid, sulbactam, tazobactam.
How do cephalosporins work?
Beta lactam drugs that are less sensitive to penicillinases. Don’t cover listeria, mycoplasma, chlamydia, MRSA, or enterococci
First generation cephs
Cefazolin, cephalexin – used for gram + proteus, e.coli, klebsiella
Second generation cephs
Cefoxitin, cefuroxine, cefaclor. Used for Haemophilis, enterobacter, neisseria, proteus, e.coli, klebsiella, serratia.
Third generation cephs
Ceftriaxone, cefotaxime, cefazidime
Used for serious gram negatives (meningitis, gonorrhea, pseudomonas)
Fourth generation cephs
Cefepime (good activity against pseudomonas and gram positives)
Fifth generation cephs
Ceftaroline. Broad gram positive coverage, but DOES NOT cover pseudomas.
Side effects of cephalosporins
HSR’s. Vitamin K deficiency. Increases the nephrotoxicity of aminoglycosides.
Aztreonam mechanism and usage
Monobactam drug, resistant to beta lactamases. Binds to PBP3. Synergistic with aminoglycosides.
Used for gram negative rods only. No activity aginast gram positives or anaerobes.
Also used for people allergic to penicillin who can’t tolerate aminoglycosides due to renal insufficiency
Carbapenems (imipenem, carbapenem, ertapenem, meropenem) mechanism and usage
Broad sprectrum betalactamase resistant drugs.
Used for gram positive cocci, gram negative rods, anaerobes.
Lots of SE that include GI upset and seizures
Why are carbapenems (imipenem) administered with another drug? What is that drug?
Administered with cilastatin that inhibits the dihydropeptidase in renal tubules. This increases its activity.
Toxicity of carbapenems
GI upset, seizures, skin rash.
Meropenem has better profile
Vancomycin
Inhibits cell wall peptidoglycan formation by binding to the D-Ala-D-ala portion of cell wall precursors.
Used for only serious gram positive reactions
Toxicity of vancomycin
Usually trouble free, but occasionally not. Nephotoxic, ototoxic, thrombophlebitis.
Can cause red man syndrome
Protein synthesis inhibitors
Inhibit components of the 30S and 50S subunits of the 70S bacterial ribosomal complex. Human ribosome 80S is unaffected.
Include Aminoglycosides, Tetracyclines (30S)
Chloramphenicol, clindamycin
Erythromycin (macrolides)
Linezolid
(50S)
Aminoglycosides (Gentamycin, neomycin, amikacin, tobramycin, streptomycin). Anything prohibitive about them?
Bactericidal, inhibit the formation of the initiation complex and cause misreading of RNA. REQUIRE O2 FOR UPTAKE, so cannot kill anaerobes.
Used for severe gram negative infections like francisella or pseudomonas. Synergistic with beta lactams
Toxicity of aminoglycosides
Nephotoxicity (especially with cephalosporins), ototoxicity (especially with loop diuretics), neuromuscular blockade.
How are aminoglycosides inactivated?
bacteria can acetylate, or phosphorylate, or adenylate.