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39 Cards in this Set
- Front
- Back
What are the different antibiotics covered in this lecture: 11
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-tetracyclines
-glycylcyclines (tigecycline) -chloramphenicol -oxazolidinones -sulfonamides -trimethoprim -quinolones -rifamycin -metronidazole -nitrofurantoin -methenamine |
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What is tetracycline mechanism of action?
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-inhibits protein synthesis by binding to ribosomes (bacteriostatic)
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What bacteria does it target?
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-staph, strep, gram negatives, anaerobes
-Rickettsiae, ehrlichia, mycoplasma, borrelia, pasteurella, brucella, yersinia, francisella, V. cholera, chlamydia, bacillus, plasmodium (malaria) |
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What are adverse side effects of tetracyclines:
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GI upset
-minocycline: vertigo; -demeclocycline; photosensitivity ; -deposited in bone and teeth; discolored teeth; |
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What does tetracycline do when treating pneumococcal meningitis:
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antagonizes penicillin
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What is tetracycline absorption decreased by and What form of tetracycline causes fanconi syndrome?
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-absorption decreased by divalent/trivalent cations (calcium, magnesium, iron, aluminum);
-fanconi syndrome from outdated/ expired tetracycline; degrades over time |
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glycylcyclines (tigecycline): what is it a derivative of?
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-tetracycline (so same mech of action)
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What is benefit of glycylcycline (tigecycline) over tetracycline?
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increased spectrum of activity; active against many tetracyclien resistant gram positive bacteria (MRSA; streptococci, enterococci; gram neg. bacteria and anaerobes/ same adverse effects though
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What is the mech of action of chloramphenicol and why is it rarely used?
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-binds to 50S ribosome (also to mitochondrial ribosome)
-therefore not used b/c can cause grey baby syndrome (lower conjugation and lower excretion); |
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What are other adverse side effects of chloramphenicol?
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-bone marrow; aplastic anemia (1/24,500 - 1/40,800): higher rate of leukemias in those that recover
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oxazolidinones: What is a synthetic compound of oxazolidinones?
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-Linezolid
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What is the mech of action of oxazolidinones? and what is a main adverse effect?
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inhibits protein synthesis!
-bacteriostatic against S. aureus and enterococci: -bactericidal against S. pneumoniae -adverse effect; Thrombocytopenia! |
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What is sulfonamide similar in structure to? Therefore, what type of organism does it target?
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-similar in structure to para aminobenzoic acid (PABA) that is used to synthesize folate
-therefore susceptible organisms are thost that must synthesize their own folate -bacteria and humans that used preformed folate are NOT affected! |
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-What do substitutions at the amide result in? how specifically does the sulfonamide work?
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-substitutions result in compound more active that may affect absorption; solubility, GI tolerance
-competitively inhibits incorporation of PABA into dihydrofolic acid; microbial enzyme (dihydropteroate synthetase |
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what bacteria does it cover/
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-gram positive and negative bacteria and nocardia; however many bacteria have developed resistance
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What do you use ot treat toxoplasmosis?
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-sulfadiazine + pyrimethamine
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what treats infected burns?
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silver sulfadiazine
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What are adverse effects of sulfonamides?
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-GI upset, WBC abnormalities, thrombocytopenia, rash, hypersensitivity, and death
-in newborns: kernicterus (sulfa displaces bilirubin from albumin) |
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Trimethoprim: function: how much more potent than sulfa is it? where does it penetrate?
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-dihydrofolate reductase inhibitor (DHFR) inhibitor
-potentiates sulfonamide and 20-100x more potent than sulfa -PENETRATES INTO PROSTRATE |
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What is it used in combo with sulfa to treat?
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-pneumocystis jiroveci (formerly pneumocystis carinii); Stenotrophomonas; tropheryma whippelii)
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adverse effx of trimethroprim:
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-megaloblastic anemia, leukopenia, granulocytopenia
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Trimethoprim/ sulfa:
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sulfamethoxazole to TMP 800 mg - 160 mg (5:1):
-tmp/smx should not be used to treat group A strep pharyngitis since no eradicate streptococcus |
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What are quinolones derivatives of and what structural difference do newer quinolones have/
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Derivative of nalidixic acid
-fluorine at position 6 |
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What do quinolones do? gram negative vs. gram positive
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-inhibit DNA synthesis
-GRAM NEGATIVES: primary target is topoisomerase II (DNA gyrase) ; introduces negative supercoils into the DNA gram positives: primary target is topoisomerase IV; -bactericidal |
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-What types of quinolones target gram negative:
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-nalidixic acid, ciprofloxacin, norfloxacin, ofloxacin
-P. aeruginosa ciprofloxacin (increases resistance, however) |
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-Is quinolone active against INtracellular bacteira/
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yes! chlamydia, mycoplasma, legionella, brucella!
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- What type of quinolone has improved gram positive activity?
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-moxifloxacin
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What are adverse side effects of quinolones?
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-seizures, rash, tendon rupture
-hypoglycemia (gatifloxacin) -arthropathy in immature animals ;hence NOT given to children! |
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Quinolones: What is absorption decreased by?
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-decreased by divalent cations (calcium, magnesium, iron, etc)
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What are two types of rifamycins and what types of compounds are they? what do they diffuse through? What is the primary mechanism of action
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-rifampin and rifabutin
-macrocyclic compounds soluble in organic solvents; diffuse through lipids inhibit bacterial DNA dependent RNA polymerase |
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What is rifamycin active against/
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activea gainst mycobacteira nd gram positive and gram negative bacterai;
mutational resistance rapidly develops; must be used in combo wiht other antibacterial agents: |
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Rifabutin activity:
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MAI
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rifampin activity:
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M. tuberculosis.
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adverse effects of Rifamycin:
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-turns body fludis (urine, saliva, tears, seat); orange-red;
-rash and hepatotoxicity |
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How does metronidazole work?
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-alters cell membrane electrochemical potential
- |
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What types of things does metronidazole target?
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-anaerobic bacteria; bacteroides fragilis c. difficile; protozoa (Trich, giardia; disulfiram-like reaction)
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-How does nitrofurantoin work and what is it active against? What type of treatment is it NOT used for?
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-damages DNA, active against E. coli, enterococci;
-not for treatment of pyelonephritis or prostatitis! |
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-What are the adverse effects of Nitrofurantoin?
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-hypersensitivity, rash, fever, chills, leukopenia, granulocytopenia, hemolytic anemia, cholestatic jaundice, hepatocellular damage, acute pneumonitis;
-long term use can lead to interstital pulmonary fibrosis |
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Methenamine: what does it do?
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-urinary tract antiseptic
-releases formaldehyde at an acidic pH -nearly all bacteria are susceptible proteus and other urea splitting bacteria raise urinary pH!!! |