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Tetracyclines bind to the ____ site of the ___ ribosomal subunit.
A, 30s
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Tetracyclines prevent ________ ____ from binding, inhibiting elongation of the protein being synthesized.
aminoacyl tRNA
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True or false. Tetracyclines are taken up efficiently by mammalian cells.
False
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What are the 3 primary mechanisms for resistance for tetracyclines.
1. decreased entry or acquistion of efflux transporter
2. Presence of ribosomes protection proteins which blocks tetracycline access to the ribosome.
3. Enzymatic inactivation of tetracylines
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Are tetracylines broad spectrum or narrow spectrum antibiotics.
Broad spectrum
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Tetracyclines have more activity against gram ____ bacteria and also some against gram _____ bacteria.
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Tetracylines can be used for Acne treatment and inhibit _________.
propionibacteria
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A major adverse effect with women who took tetracylines while pregnant, and the adverse effect seen in their children is?
Teeth discoloration
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Tetracycline absorption is impaired by the concurrent ingestion of ________, antacids, _______, dietary Fe and ___ supplements
- dairy products,
- Pepto-Bismol,
- Zn
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Chloramphenicol binds to the bacterial ____s large ribosomal subunit
50
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The primary route of elimination for most tetracylines is the kidney. But Doxycyline is _________ and Minocycline is mostly _______
- Both Hepatic and renal,
- hepatic
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Chloramphenicol Blocks protein synthesis by which MOA.
inhibits the transfer of the peptide form the P site to the A site. (TRANSPEPTIDATION reaction)
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T/F. Chloramphenicol can also bind to and inhibit mitochondrial large ribosomal subunit. Mostly in the cells of bone marrow.
True
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What is the primary mechanism of resistance for Chlormaphenicol?
Acetylation of the drug
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The antibacterial spectrum for Cholamphenical most gram negative bacteria and most gram positive _________.
anaerobic cocci
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Which drugs can be used to treat Rickettsia (rocky mountain spotted fever)
- Chlormphenicol,
- Tetracylines
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When Chloramphenicol is given in high doses to infants and can cause_________.
Gray Baby syndrome
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Chloramphenicol inhibits CYP______ causing prolonged half lives of other drugs.
CYP 450
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_________ and _________ bind to nearby sites of the ribosome, and thus bind _________ with chloramphenicol.
- Macrolides,
- clindamycin,
- Competitively
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The differences on the macrolide stucture are responsible for 3 things.
- stability
- antibacterial spectrum
- tissue penetration
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T/F macrolides bind reversibly to bacterial 50s large ribosomal subunits.
True
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Macrolides inhibit ______ and block ______ synthesis.
Translocation, protein
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Most Macrolides are bacteriostatic but can they be bactericidal and if so when?
YES, at high concentrations
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Name the 4 main mechanisms of reistance for Macrolides.
1. Drug efflux form the cell
2. Addition of methly group to the ribosome (by a methylase) causing a reduction in the affintiy of the ribosome to the macrolide.
3. Hydrolysis of macrolide by an esterase
4. Chromosomal mutations that alter a 50s ribsomal protein
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Erythromycin and Clarithromycin (macrolide) are most effective against Gram ______ bacteria and some activity against Gram ______ bacteria..
Postitive, Negative
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T/F Azithromycin has more activty against Gram positive bacteria than other macrolides.
FALSE
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Erythromycin and Clarithromycin interfere with CYP _____
CYP450
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T/F Macrolides, chloramphenicol and chlindamycin bind to nearby sites of the ribosome , thus interact competitively.
TRUE
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Teliithromycin is a ketolide and is a semi-synthetic derivative of _________.
erythromcyin
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Telithromycin has ______ resistance because it is less susceptible to __________ mediated and efflux- mediated mechanicams of reistance.
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Clindamycin has a similar MOA with _______ because it; inhibits the transfer of the peptide form the ____ site to the ____ site (TRANSPEPTIDATION reaction)
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Clindamycin binds to the ____ ribosomal subunit
50s
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Clindamycin is effective against Gram ____ bacteria and some against Gram _____ bacteria. and is used to treat acne _______.
- Postitive
- Negative
- vulgaris
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T/ F Macrolides, chloramphenicol, and clindamycin bind to nearby sites on the ribosome, and thus interact competitively with one another.
True
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Streptogramins are adminstered in a 30:70 combination. What is the 30 and what is the 70?
30= Streptogramin B (Quinupristin)
70= Streptogramin A (Dalfopristin)
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Is Streptogramins bacterostatic or bacterocidal?
Bacterocidal
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What are the MOAs for Streptogramins?
1. Bind to 50s ribosomal subunit.
2. Steptogramin B Binds to the same site as macolides inhibiting Translocation.
3. Streptogramin A binds to a nearby site. causing Streptogramin B to be enchance binding and also interferes with the polypepide chain formation
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Streptogramins becomes resistant by which 4 ways.
1. Ribosomal methlyase
2. Lactonase (hydrolis)
3. Acetyltransferase
4.Efflux transporter
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Streptogramins are effective against many Gram _____ cocci.
Postitive
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T/F Streptogramin is effective against most gram negative bacteria.
FALSE
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Streptogramin are inhibitors of what CYP?
CYP 450
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Linezolid binds to the 50s ribosomal subunit, and also prevents formation of the complete _____ ribosome, causing the blockage of _______ initiation.
70s, translation
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T/F Linezolid can be bacterodstatic or bactericidal depending on concentration.
True
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Linezolid is effective against gram -_______ and ineffective against most gram _____ bacteria
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Which 2 drugs are used in reserved for treating multi-drug resistant bacteria (e.g. Enterrococcus faecium, Staphylococcus aureus, and Streptococcus pyogenes).
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