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32 Cards in this Set
- Front
- Back
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The "cillans" all contain ____ that inhibits ________.
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beta-lactam structure; transpeptidase
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Cephalosporins...
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are other antibiotics that contain the beta-lactam structures.
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How does rsistance occur in the "cillans"?
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when the beta-lactamase (pennicillinase) is acquried by the pathogen
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What are the different types of "cillans" and what makes them different?
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1. Penicillin G - good against Gram +, not -; destroyed by stomach acid
2. Penicillin V - same as G but more acid resistant 3. Ampicillin - good against Gram +/- and acid stable 4. Carbenicillin - same as amp, but not well absorbed by small intestines |
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Vancomycin
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Very Large; used against Gram +; binds to D-Ala--D-Ala residues and blocks transpeptidase as well as other steps in cell wall synthesis.
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Explain the resistance of Vancomycin
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it is due to changing final D-Ala to other AA or similar structure.
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VRE
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Vancomycin resistant enterococcus; it is known to transfer resistance horizontally
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Types of protein inhibitors.
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Aminoglycosides, Tetracyclines, Erythromycin, Chloramphenicol
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Aminoglycosides are...
Why is the resistance widespread? |
a type of Protein synthesis inhibitor that contain a cyclohexane and aminosugar; The resistance is widespread due to enzymatic modification and mutations in the ribosome components; work by binding 30S ribosomal units
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Tetracyclines are...
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another type of Protein synthesis inhibitor that contains 4 ring structures; they bind to 30S ribosomal subunits to inhibit tRNA binding; Resistance is due to many factors
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Erythromycin
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the basic class of it is macrolide;
binds to 23S; resistance due to change in the 23S rRNA sequence or macrolide-digesting enzyme. |
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Chloramphenicol
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binds to 50S;
CAT (chloramphenicol acetyl transferase) is a common gene on Tn's, it adds an acetyl group to the chloramphenicol which helps resistance. |
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Metabolic antagonists
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inhibit some sort of metabolic pathway;
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WHat are sulfonamides?
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PABA analogues that prevent the first step in folic acid production (ex: sulfamethoxazole); Resistance is due to mutations in the synthetase or by acquiring THF transport genes.
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What is Trimethroprim?
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It inhibits the second step in folic acid production, by inhibiting Dihydrofolate reductase. Resistance is due to mutations in the DHFR and Tetrahydrofolic acid.
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What is the treatment for metabolic antagonists?
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two antibiotics to get both parts in the pathways (bactrim & septra)
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Topoisomerase inhibitors
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chemically classified as quinones; kill cells and prevent cell division by inhibiting Type II & IV topoisomerases; Resistance is due to mutations in topoisomerases.
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Antibiotic resistance mechanisms
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1. alter permiability or entry pathway for antibiotic
2. chemically modifiy antibiotic 3. mutation in the target 4. Efflux pump pumps a wide assortment of antibiotics out. |
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Resistance-conferring genes are found....
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on transposons and R-plasmids, so horizontal transfer is common.
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Many antifungals are toxic to the host because....
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fungi are eukaryotic
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What are potential fungal targets?
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1. Chitin - in the cell wall, being studied.
2. Ergosterol - fungi use this instead of cholesterol (antifungals that attack it: azoles, amphotericin, nystatin) 3. Microtubule function - Ex: griseofulvin |
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What do most antiviral drugs target? Many are ____.
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Replication, because they use our cells to function. Nucleoside analogues.
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Antivirals that have specific targets?
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1. HIV protease inhibitor ritonavir
2. neuraminidase inhibitor tamiflu 3. influenza virus uncoating inhibitor amantidine |
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Resistance to antiviral drugs is....
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common, because viral replication is ofter error prone.
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What is the process of making monoclonal antibodies?
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1. Inject a mouse with antigen
2. Harvest spleen containing B cells 3. Fuse spleen cells to myeloma cells 4. Isolate each fused cell, grow & screen 5. Grow up high production hybridomas 6. Isolate antibodies. |
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Immunofluorescence microscopy
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uses antibodies covalently attached to fluorescent tags.
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Two kinds of Immunofluorescence microscopy
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1. Direct: labeled antibody binds to antigen on specimen.
2. Indirect: Antibodies used are not fluorescently labeled, they bind to antigen. Labeled antibody then binds to previous Ab |
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What does ELISA stand for?
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Enzyme-linked immunosorbent assay
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Direct ELISA
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Looking for the amount of antigens; uses microtiter plates pre-coated with bound, unlabelled, Abs to trap Ag; a second tagged (enzyme-linked) Ab to the Ag is added and the amount of the 2nd Ab is determined.
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Indirect ELISA
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Used to look for serum Abs to particular substances (looking for exposure); Microtiter plates are covered with the Ag, the serum is added, then the tagged Ab is added & quatified.
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Agglutination tests...
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quick procedures (no need for spectophotometer, can be done in the field), depends on the abilities of Abs to form immune complexes with Ags. Typically IgMs are used because when secreted it is pentavalent.
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Negatives of Agglutination tests
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needs several dilutions of antibodies and/or antigens since complexes form at specific ratios of Ab:Ag.
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