Micro Exam 2: Antibiotics (more specific) – Flashcards
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| What is Gentamicin? |
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| most commonly prescribed aminoglycoside |
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| What is Tobramicin? |
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| an anti-pseudomonal aminoglycoside |
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| What is a common first line antibioitic for uncomplicated UTI's?; |
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| TMP/SMX |
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| Which drugs require therapeutic drug monitoring? |
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| drugs with low therapeutic range; aminoglycosides and vancoymycin |
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| Combination therapy may prevent the emergence of resistance of what? |
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| What are transglycosylases? |
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| they are a PBP that is takes nascent peptidoglycan to backbone of cell wall; |
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| What are carboxypeptidases and transpeptidases?; |
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| Beta lactams are contraindicated in what type of patient? |
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| patient with immediate hypersensitivity reaction history! |
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| if there is a history of skin rash with penicillins, what should you use? |
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| cephalosporins are almost always safe! |
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| What are types of glycopeptides? What do they act against?; |
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They are cell wall active agents;; vancomycin/teicoplanin act against gram positive!! |
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| What is the action of glycopeptides?; |
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| bind to terminal D-ala of nascent cell wall peptides and prevent cross-linking of these peptides to create mature peptidoglycan |
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| What are the 2 types of cell wall active agents? |
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| S. pneumoniae is responsible for what type of B-lactam resistance? |
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| altered PBPs |
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| MRSA is responsible for what type of beta-lactam resistance? |
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| Novel PBPs |
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| What are the 4 types of B-lactam resistance? |
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| Glycopeptide resistanct is a primary concern for which microorganisms? |
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| enterococcus and S. aureus |
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| Mechanisms of glycopeptide resistance: |
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| altered target/ substitude D-lac for D-ala and vancomycin can no longer bind |
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| Beta-lactamase inhibitors do not affect which microorganisms?; |
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| pseudomonas or enterobacter |
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| List 2 beta-lactamase inhibitors and their relative beta-lactam drugs: |
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| List bacteria which can be inhibited by beta-lactamase inhibitors:; |
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| What does MLS stand for and what type of antibiotic are they? |
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| List protein synthesise inhibiting antibioitics: |
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| Most common macrolide and what to look for to decide whether an antibiotic is a macrolide: |
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| What subunit of ribosome do macrolides bind to? |
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| 50s |
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| Two mechanisms of action of macrolides include: |
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| Macrolide resistance is caused by two (three kind of) mechanisms, what are they? What genes code for them? What phenotype? |
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| Active Efflux resistance is resistance to which antibiotic only? |
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| macrolides |
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| is ribosomal modifications of macrolides inducive or constitutive? |
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| inducive |
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| methylate adenine 2058 of 23s rRNA has to do with what antibiotic and what process? |
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| macrolides (also MLSB;phenotype) and process of ribosomal modification resistance (target site modification) erm(B) can be other letters |
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| What are the 4 first choices of macrolide uses? |
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| What are 2 second choice uses of macrolides? |
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| pyogenic streptococcal infections and C jejuni gastroentitis |
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| What is different about 2nd generation fluroquinolones? What mechanisms of action and name of drug.; |
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ciprofloxacin - anti-pseudomonal and broader spectrum |
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What is different about 3rd generation fluroquinolones? What mechanisms of action and name of drug.; |
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Moxifloxacin - enhanced gram positive +/- anaerobic |
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| what is Qnr resistance? |
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| protection of topoisomerase in fluroquinolone action |
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| How is acquired resistance to fluroquinolones achieved? |
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| acquisition of resistance determinants from viridans streptococci |
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| First aminoglycoside and date? Are they natural? |
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| Aminoglycoside activity against gram positive and negative? |
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| When deciding if aminoglycoside or not?; |
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| Do aminoglycosides work in absesses? Why or why not?; |
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NO NO NO, do not work in any anaerobic conditions they gain entry into inner membrane through energy dependent transport system - depend on the electron transport chain where O2 is needed |
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| What step of aminoglycoside action is rate limiting and by what? |
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| the active transport through inner membrane is rate limiting and binding; blocked by divalent cations and anaerobiosis |
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| Is binding of aminoglycosides reversable or irreversable? What ribosomal subunit do they bind to? |
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| What part of protein production does aminoglycosides inhibit? |
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| proofreading; causes aberrant or truncated proteins |
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| Can aminoglycosides affect mammalian cells? |
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| yes, at high concentrations it affects proteins (thats why it has a low therapeutic range with vancomycin!!) |
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| What are the three mechanisms of aminoglycoside resistance?; |
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| What is the most common form of aminoglycoside resistance?; |
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enzymatic modification! - ;70 enzymes; plasmid mediated, different substrate specificities |
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| What drugs inhibit metabolic pathways? |
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trimethoprim and sulfonamides (TMP AND SMX) SMX stands for sulfonamethoxazole |
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| TMP/SMX action against gram positive and negative |
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| good gram negative, some gram positive |
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| sulfonamides act at what part of metabolic inactivation? |
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| mimic PABA and stop transformation of PABA to dihydrofolic acid by tetrahydropteric acid synthetase |
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| trimethoprimes act at what part of metabolic inactivation |
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inhibit dihydrofolate reductase stops dihydrofolic acid from being tetrahydrofolic acid |
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| TMP/SMX is commonly used for uncomplicated what? |
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| UTI infections |
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| What is TMP/SMX used against |
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| Mechanisms of metronidazole action |
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short lived toxic intermediates or free radicals that damage DNA and other macromolecules ; |
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| does metronidazole have a high or low bioavailability orally (PO) |
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| high (;90%) |
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| Does metronidazole have a long or short half life? |
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| LONG - take bidaily |
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| side effects of metronidazole use |
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| metronidazole resistance? price? |
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| Uses of metronidazole |
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| define transglycocylation; |
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| the process where building blocks of peptidoglycan are added to the peptidoglycan backbone |
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| generations of cephalosporins are divided based on: |
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| spectrum of activity |
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second generation cephalosporins are also known as: 3rd generation are: |
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| what worries people about VRE and MRSA in hospitals |
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| VRE is resistant to drug that can be used against MRSA so scared that gene will transfer |
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| What is the best macrolide drug today? |
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| clarithromycin |
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| what macrolide drug is bad to take - rips gut and you have to take many doses a day? |
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| erythromycin |
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| In terms of Target Site Modification and Efflux pumps (in macrolides), which gives you low level resistance and which gives you high level resistance? |
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| efflux = low level; TSM = high level |
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| can you get resistance from down regulation of porin channels? |
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| NO, if you have efflux AND downregulation you can though (these are acquired genes) |
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| why must mycoplasma be treated with macrolides? |
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| because mycoplasma doesnt have a cell wall! - it causes lower pneumonia (microlids are used for lower tract infections - upper you use something else) |
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| Are fluroquinolones natural or synthetic? |
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| completely and totally SYNTHETIC - not found in nature |
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| what were fluroquinolones first designed for? |
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| malaria |
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| What kind of drug is a respiratory fluroquinolone? |
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| Moxifloxacin and other 3rd gen ..? |
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| What are the best 2 drugs to treat patients with anaerobic infections? |
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| metronidazole and clindamicin; |
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| Can you take metronidazole and drink alcohol? |
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| hell no sir. (violently sick) |
