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48 Cards in this Set
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- Back
- 3rd side (hint)
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List all the classes of antibiotics that interfere with bacterial protein synthesis
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Lincosamides
Oxazolidinones Tetracyclines Streptogramins Macrolides Aminoglycosides Chloramphenicol Ketolides "these classes SMACK aLOT of ribosomes" |
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What are the main differences between prokaryotic and eukaryotic ribsomes?
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Prokaryotes:
30s+50s ribosome subunits Eukaryotes: 40s+60s ribosome subunits |
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Whats "transpeptidation"?
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Crosslinking by "cell wall transpeptidase"(PBP).
But its also the connection of an amino acid to a growing polypeptide in a ribosome during translation |
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List the tetracyclines.
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Tetracycline(original)
Demeclocycline Doxycycline Minocycline Glycylcyclines(Tigecycline) |
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What is the spectrum of activity of the tetracyclines?
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VERY broad(theoretically):
gram - gram + aerobes anaerobes atypicals Bacteriostatic However they have lots of resistance |
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Whats the MoA of tetracyclines?
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"A" site inhibitor:
Binds to the 30s ribosomal subunit and inhibits protein synthesis by blocking the attachment of charged aminoacyl-tRNA to the "A" site on the ribosome. |
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What is the MoA of bacterial resistance to tetracyclines?
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Upregulated efflux pumps
Self-methylation of its 30s ribosomes to dec affinity of tetracyclines for "A" site Enzymatically adding an acetyl group to tetracyclines (using acetylase) |
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What is Tigecycline's indication? Spectrum?
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Newer tetracycline with broader spectrum
Used for complicated wounds, MRSA, VRE Higher affinity for site "A" than other tetracyclines Parenteral only No resistance to Tigecycline yet, kept in reserve |
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What are Doxycycline and Minocycline used for?
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Everything older tetracyclines are used for (mainly atypicals) plus: Acne
Ok to take these with dairy (less chelation of Ca+) |
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List some AEs of tetracyclines
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Stains teeth of kids under 8 yo(and fetal teeth so contra in pregnancy)
Chelates ca++, mg++, fe++ Contra with these antacids or supplements Suprainfection(kills normal flora -> yeast infection) Photosensitivity(esp Demeclocycline, Doxycycline) Rash(due to allergic reaction) |
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MoA of Chloramphenicol?
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Binds to 50s rib between "A" and "P" sites preventing traspeptidation/connection of the amino acid to the growing chain
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Spectrum of Chloramphenicol?
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Broad spectrum
Crosses BBB |
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List AEs of Chloramphenicol.
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Inhibits mitochondrial protein synthesis in eukaryotes leading to bone marrow suppression(dec wbc's, rbc's, platelets)
So rarely used |
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What is the MoA of resistance to Chloramphenicol?
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Acetylation of Chloramphenicol, lowering its binding affinity to 50s subunit
Upregulation of efflux pumps These are plasmid mediated YET little resistance since we dont use it much |
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Whats "translocation"?
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The moving of an already connected polypeptide chain within a ribosome(from one site to another).
Translocation comes after transpeptidation. Both are targets of antibiotics |
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List the macrolides.
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Erythromycin
Clarithromycin Azithromycin |
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MoA of macrolides?
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Binds to the 50s ribosomal subunit between the "A" and "P" sites (like chloramphenicol), but it prevents translocation (not transpeptidation like chloramphenicol does)
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ADME of macrolides?
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Bacteriostatic
Has a lactone ring Well absorbed orally Dont cross BBB Cell and tissue levels are higher than serum levels(esp Azithromycin, Clarithromycin) |
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Resistance MoA(s) for macrolides?
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Efflux pumps upregulated
Esterases inactivate (open up) lactone ring Self-methylation of 50s subunit dec's binding affinity of macrolide. |
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What is the clinincal use for macrolides?
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Upper respiratory infections(g-, g+)
Atypicals |
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AEs of macrolides?
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Gastrointestinal discomfort, diarrhea(binds to motilin rx)
Cholestatic hepatitis Arrhythmias |
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Drug interactions(DIs) with macrolides?
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Erythromycin and Clarithromycin inhibit cyp450-3a4, so they dec metabolism of other drugs metabolized by cyp450-3a4, so possible toxicity when co-administered with:
Carbamazepine, Valproic acid Digoxin Warfarin |
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What is Telithromycin, MoA?
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A Ketolide(subgroup of macrolides derived from Erythromycin)
Same MoA as macrolides |
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What is Telithromycin clinically used for?
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Same as macrolides:
Upper respiratory infections Atypicals |
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What class is Clindamycin? Its MoA?
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Lincosamide
Binds to 50s and prevents translocation |
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What is Clindamycin used for?
What should it NOT be used for? |
Gram +
Some g- anaerobes Do not use for Clostridium difficile infections. Clindamycin kills off normal flora, but not Clostridium, so possible Clostridium difficile overgrowth might occur leading to pseudomembranous enterocolitis |
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ADME of Clindamycin?
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Well absorbed
Doesnt cross the BBB Accumulates in WBCs Hepatic metab |
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While the macrolides can be used for other infections, their greatest utility is for ____?
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Atypicals
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What are streptogramins? their MoA?
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Mainly the combo drug Quinupristin/Dalfopristin
Quinupristin: prevents polypeptide elongation during translation also causes the incomplete polypeptide to be released prematurely Dalfopristin: enhances the binding of Quinupristin to the 50s by 100x interferes with transpeptidation(peptide chain formation) |
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Resistance MoA to Dalfopristin?
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Acetyltransferases modify Dalfopristin
Efflux pump upregulation |
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Resistance MoA to Quinupristin?
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Self-methylation of 50s(dec's binding affinity of Quinupristin to 50s)
Lactonases open up lactone ring |
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Clinical use of Quinupristin/Dalfopristin?
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VRE
MSSA MRSA? Resistant Strep Reserved use (against gram +) Note: all the above are gram +, so dont see any gram - use |
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What class is Linezolid? Indication?
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Oxazolidinone
Used for gram + only, and multi-drug resistant gram + Reserved use |
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MoA of Linezolid?
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Binds to the 23s, and prevents binding of the 50s to 30s
Note: 23s is part of the 50s ribosomal subunit Note: 16s is part of the 30s ribosomal subunit |
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What is Mupirocin used for? Spectrum?
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Topical antibiotic for skin infections
Broad spectrum (aka "bactroban") |
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What is the MoA of Mupirocin?
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Inhibits bacterial translation by:
inhibiting isoleucyl tRNA synthetase (which normally "charges" the tRNA by attaching an amino acid to it) Note: most antibiotics that interfere with translation are bacteriostatic, however Mupirocin is bacteriocidal |
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C. difficile is spread by ___?
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People and things(eg jewelry) in hospitals typically.
It has spores that can last for "40 days in a cleaned room", so the longer you're in the hospital, and on antibiotics, the higher the chance you'll get this infection. |
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What drugs typically cause pseudomembranous enterocollitis?
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Clostridium difficile + Clindamycin or
Broad spectrum antibiotics(eg cephalosporins, doxycycline) or PCN based antibiotics(eg amoxicillin) |
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Pseudomembranes are ____?
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Sheets of dead cells usually due to C. difficile toxin killing the top layer.
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Linezolid interactions?
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Linezolid acts as a weak MAO-i, so dont eat foods rich in tyramine like red wine, smoked cheese/meat.
MAO-i's prevent the breakdown of tyramine, which enters the blood and acts like amphetamine. |
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Which of the antibiotics discussed are on reserved use?
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Tigecycline
Telithromycin Quinupristin+Dalfopristin Linezolid |
On the TIGEr RESERVE, I look at them with my TELIscope, hoping they wont cross the LINE, else my body will no longer be in PRISTINe condition
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Which of the antibiotics discussed are used to treat atypicals?
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Tetracyclines
Macrolides Telithromycin |
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Which of the antibiotics discussed are plasmid mediated?
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Tetracyclines
Chloramphenicol |
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Whats the difference between transpeptidation and translocation?
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Transpeptidation can mean one of two things, cross-linking nag-nam strands with PBP in the cell wall, or connecting an amino acid to the growing polypeptide chain during translation
Translocation refers to moving the polypeptide chain from the A site to the P site during translation |
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Which antibiotics can cause pseudomembranous enterocolitis?
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Clindamycin
Ampicillin Cephalosporins Amoxicillin Tetracyclines(less so) |
Pseudomembranous enterocolitis makes is hard to go CA-CA
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Which of the antibiotics discussed can be used to treat MRSA?
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Quinupristin+Dalfopristin
Tigecycline Mupirocin |
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Which of the antibiotics discussed can be used to treat VRE?
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Quinupristin+Dalfopristin
Tigecycline |
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Which of the antibiotics discussed inhibit CYP3a4?
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Macrolides
Ketolides/telithromycin Quinupristin+Dalfopristin |
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