Antibiotics Flashcards by E E

What are some 30S inhibitors?

Aminoglycosides

Tetracycline

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Are

linezolid

macrolides

chloramphenicol

clindamycin

quinupristin/dalfopristin

30S or 50S inhibitors?

50S inhibitors

*NOTE* linezolid, tetracycline and chloramphenicol interfere with mitochondrial ribosomes - do have effect on us, ie, bone marrow suppression.

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What part of translation do linezolid and aminoglycosides inhibit?

Initiation

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What part of translation do aminoglycoside, tetracycline, macrolide, chloramphenicol, clyndamycin, quinupristin/dalfoprisitin inhibit?

Elongation

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Where else does aminoglycoside inhibit translation?

termination

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Are most ribosome inhibitors bacteriostatic or bacteriocidal?

how about things that affect the cell wall?

bacteriostatic.

those would be bactericidal

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What do linezolid, tetracycline, and chloramphenicol interfere with?

mitochondrial ribosomes (bone marrow suppression)

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What are the steps of prokaryote translation initiation?

1) Initiation factors associate with the 30S ribosomal subunit.
2) Formylmethionine initiator tRNA and mRNA bind to 30S subunit.
3) 50S ribosome then binds and you have the complete initiation complex.

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Where does Linezolid bind?

P-site on the 50S subunit

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where do aminoglycosides bind and what do they do?

bind to 30S ribosome and freeze initiation complex

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Elongation:

Aminoacyl tRNA is inserted in the acceptor site. ____________ interfere here and prevent aminoacyl tRNA attachment to the acceptor site.

TETRACYCLINES

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Elongation:

The peptide bond is formed. ____________ inhibits peptide bond formation.

Chloramphenicol

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Elongation:

fmet tRNA is released from the P site. In prokaryotes, an exit site called the E site binds tRNA after it’s displaced from the P site
Translocation. A dipeptide tRNA moves from the A to the P site and the ribosome moves one codon along the mRNA. _______________________________ inhibit translocation.
Another amino acyl tRNA is put in the A site and elongation continues.

Macrolides, Streptotagmins, Clindamycin

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what antibiotics should you not use with newborns?

Chloramphenicol (can’t glucuronidate)

Erythromycin (piloric stenosis)

Sulfonimides

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What antibiotics can you not use in children?

Tetracyclines

Fluoroquinolones

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What antibiotics should you not use during pregnancy?

Tetracycline

Aminoglocosides,

Clarithromycin

Fluoroquinolones

Chloramphenicol

Sulfonimides

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What do you need to do with antibiotics for the elderly?

Adjust for reduced renal funtion:

the half life of

beta-lactams

aminoglycosdes

and fluoroquinolones

will be increased

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Where do Aminoglycosides

Streptomycin

Neomycin

Amikacin

Gentamicin

Tobramycin

do in Protein Synthesis?

Are they bactericidal, bacteriostatic?

BacterioSTATIC…act on 30S ribosome

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What do the Tetracyclines -

Doxycycline,

Minocycline

Demeclocycline

Tetracycline

do in protein synthesis?

Are these bacteriostatic or bactericidal?

inhibit - act on 30S Ribosome

BacterioSTATIC

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Where do Macrolides -

erythromycin

azithromycin

clarithromycin

cindamycin

chloramphenicol act in Protein Synthesis?

Are they bacteriostatic or bactericidal?

act on 50S ribosome…

Bacteriostatic

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Resistance mechanism that prevents drug from reaching its target in

Beta-lactams
Rifampin
Fluoroquinolones
Sulfonamides
Trimethoprim

Linezolid
Aminoglycosides
Erythromycin, clindamycin, quinupristin/dalfopristin
Tetracyclines

are due to:

alteration of target

Beta-lactams – altered penicillin binding proteins (MRSA)
Vancomycin- altered target
Rifampin - DNA dependent RNA polymerase
Fluoroquinolones - DNA topoisomerase II or IV
Sulfonamides - Dihydropteroate synthetase
Trimethoprim - Dihydrofolate reductase

Linezolid – altered ribosome
Aminoglycosides – altered ribosome (uncommon)
Erythromycin, clindamycin, quinupristin/dalfopristin – methyltransferase modified ribosome
Tetracyclines – production of proteins that interfere with ribosomal binding

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Resistance mechanism that prevents drug from reaching its target in

Sulfonamindes

is due to:

Upregulation of target or its substrate

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Resistance mechanism that prevents drug from reaching its target in

penicillins

Cephalosporins

Aminoglycosides

Chloramphenicol

Tetracyclines

Macrolides

Clindamycin

quinupristin/dalfoprintin, metronidazole

is due to:

Enzymatic alteration of the antibiotics

this can sometimes occur in Bacitracin and Polymyxins as well

Which drugs are reserved for difficult to treat drug resistant bacteria?

(Like MRSA or VRE - vancomycin resistant enterococcus)

5th gen cephalosporin- ceftaroline,

vancomycin,

TMP-SMX,

daptomycin,

Quinupristin-Dalfopristin,

Linezolid

Dihydropteroate synthetase targeted

Sulfonamides

Production of proteins that interfere with ribosomal bindng

tetracyclines

Resistance mech that prevent drug from reaching its target in Tetracyclines Sulfonamides Aminoglycosides Chloramphenicol is due to:

primarily decreased uptake

Resistance mechanism that prevents drug from reaching its target in ## Footnote Cephalosporins Aztreonam Tetracyclines (most impt), minocycline the exception Macrolides Quinupristin/dalfopristin Fluoroquinolones Sulfonamides is:

increased efflux

What are some differences between RNA and DNA translation?

RNA starts with formyl-methionine and the Shine Delgarno Sequence DNA starts with just methionine...invovles a 5'Cap

What is notable about quinupristin/dalfopristin?

They're 2 seperate drugs, but always used in combination

What antibiotic inhibits at all 3 steps of mRNA -\> protein translation?

aminoglycosides (which is why they're bacteriocidal - most ribosome inhibs. are bacteriostatic: they just interfere with one step)

What are concentration-dependent drugs?

Concentrations _\> 10 times above the MIC most effective_ at killing the organism

What are time-dependent drugs?

effect depends on _time_ above the MIC

are aminoglycosides time or concentration dependent?

Concentration - they're administered as a single large dose

Are B-lactams time or concentration-dependent?

Time - must have multiple doses

What drugs should be used on Mycoplasma pneumonia?

atypical pneumonia - use Doxycycline Azithromycin Levofloxacin (B-lactams not effective)

What should you use for Lymes?

amoxycillin or doxycycline....use Johns Hopkins guide

Enterococcuw drug resistance examples (Gram + organism)

What agents may cause hemolysis in patients with glucose-6-phosphate dehydrogenase deficiency?

sulfonamides (trimethoprim/sulfamethoxazole)

which antibiotic may cause seizures?

beta-lactam (esp. carbapenems)

what antibiotic may cause hepatotoxicity?

rifampin

what antibiotic may cause nephrotoxicity?

sulfonamides aminoglycosides vancomycin

what antibiotic may cause Ototoxicity?

aminoglycosides vancomycin

what antibiotic may cause QT interval prolongation?

macrolides, fluoroquinolones

what antibiotic may cause anemia?

chloramphenicol trimethoprim

what antibiotic may cause arthralgia?

quinupristin/dalfoprisin fluoroquinolones

what antibiotic may cause disulfiram-reaction when taken with alcohol?

metronidazole 2nd gen. cephalosporin w/methylthiotetrazole groups

what antibiotic may cause superinfections?

clindamycin fluoroquinolones 3rd gen. cephalosporin ampicillin

Which drugs are patients commonly hypersensitive to?

sulfonamides (shouldn't take other sulfa drugs like diuretics) B-Lactam (can use skin test to see, and then work on desensitization) clindamycin

what are common drug-drug interactions?

rifampin induces drug metabolizing enzymes (uses up other drugs faster) clarithroycin and erythromycin inhib. hepatic metabolism

Why treat with Trimethoprim-Sulfamethoxazole?

Inhibits multiple steps in folate synthesis

Why treat with Aminoglycoside+Penicillin?

Penicillin increases permeability of cell membranes increasing the ability of aminoglycosides to enter the cell

Why are Ampicillin-sulbactam, Amoxicillin-clavulanate, Piperacillin-tazobactam, Ticarcillin-clavulanate Imipenem-cilastatin used in sets like that?

Addition of inhibitors to prevent degradation of the enzyme (for example, that last set blocks renal dehydropeptidase)

What happens if you use Vancomycin and Aminoglycosides together?

each alone have some nephrotoxicity. If given together you get marked renal impairment.

Should you use penicillin or penicillin + tetracycline in treating pneumoccal meningitis?

Penicillin - 21% mortality Penicillin + Tetracycline - 79% mortality (antagonism occurs)