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Micro Antimicrobials
Question | Answer |
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Name two glycopeptide antimicrobials and their mechanism of action | Vancomycin and Techoplanin - - binds to terminal aa of peptide side chain - bactericidal - large and lipophilic - GRAM POSITIVE ONLY - not absorbed orally - can be used against MRSA |
Name the different kinds of beta lactam antibiotics | Penicillins, cephalosporins, carbapenems, and monobactams |
Describe penicillins | Active against gram positive bacteria; they are sensitive to beta lactamase. Modifications produced broad spectrum ampicillin and methicillin, nafcillin, oxacillin |
Describe cephalosporins | resistant to beta lactamase - these are classified into different generations of cephalosporins |
Describe Carbapenems | broad spectrum; they are resistant to beta lactamase - these can only be given by IV |
Describe Monobactams | active against Gram negative bacteria and are beta lactamase resistant |
What types of antibiotics are cell wall synthesis inhibitors? | Beta lactamase and glycopeptides |
Describe Clindamycin | It has a mode of action similar to macrolides; it is bacteriostatic; it has an expanded spectrum that includes gram negative anaerobes; it can mitigate toxin production by staph/Strep strains |
Describe Oxazolidnones | new class of antibiotics whose main agent is azolide; bind 50S ribosome; active agent against gram positive bacteria (those already resistant) |
Describe Macrolides and give two examples | Bind the 50S ribosome and therefore block translocation. Bacteriostatic to most gram positive some gram negative bacteria Erythromycin, azithromycin. |
Describe chloramphenicol | Binds the 50S ribosome and blocks peptidyl transferase reversibly. It is readily absorbed in the body, including the CNS. If given in too high a dose it could result in aplastic anemia |
Describe Aminoglycosides and give three examples. | Bind to the 30 and 50S ribosoems and prevent the formation of the initiation complex. MUST BE TRANSPORTED INTO THE CELL BY OXIDATIVE METABOLISM. Not well distributed in the bones or CNS. Absorbed poorly orally. Examples: streptomycin, gentamicin, neomycin |
Describe the resistance mechanisms to aminoglycosides. | enzymes that phosphorylate, adenylate of acetylate the drugs |
Describe tetracylines and microbial resistance mechanism to the antibiotics. | They bind to the 30S ribosomes reversibly to prevent tRNA attachment. They are broad spectrum antibiotics that can be absorbed oraly and have an affinity for teeth and bones. Microbes can pump out tetracyclines and are able to protect their ribosomes. |
What antibiotics inhibit folate synthesis? | Sulfamethixazole, trimethoprim, bactrim, amethopterin, pyrimethamine and septra |
What antibiotics inhibit protein synthesis | Aminoglycosides, tetracylcines, macrolides and chloramphenicol. MAT C like matt conrad |
Which antibiotics inhibit nucleic acid synthesis? | Quinolones, folate inhibitors, metronidazole, rifampin |
Describe Quinolones and name one example | Ciproflaxin is an example of a fluoroquinolones. Quinolones inhibit DNA gyrase which prevents the unwinding of DNA |
Describe Metronidozole | It induces ssbreaks in DNA The prodrug is activated by reduction under anaerobic conditions. Therefore its useful against anaerobic bacteria, fungi and parasites |
Describe rifampin | It binds to the beta subunit of RNA polymerase. It is used to treat infections of mycobacterium tuberculosis |
What drugs disrupt the cell membrane? | Polymixins binds to membranes rich in phosphtidylethanolamine - it acts a detergent and disrupts the membrane. It can be nephrotoxic and neurotoxic. |