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54 Cards in this Set
- Front
- Back
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is the MOA of tetracycline reversible
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yes its BACTERIOSTATIC
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can tetracyclins be used against atypicals
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yes as well as anaerobes, aerobes, gram +/-
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what form of tetracyclin has no antibiotic resistance
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tigecycline
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what is the mechanism of action of tetracyclines
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binds to active site at 30s ribosome subunit and prevents tRNA from coming in therefore stopping protein synthesis
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what are the forms of bacterial resistance to tetracyclines
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upregulation of efflux pumps
ribosomal protection enzymatic modification of antibiotic via esterases |
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how does ribosomal protection protect the bacteria from tetracycline
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via bacterial methylase it will methylate the active site and create steric hindrance preventing tetracycline from coming in
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what is the synthetic analog of monocycline
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tigecycline
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how is tigecycline administered
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paranterally only
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what is unique about tigecycline
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it has the same MOA: binds to 30s subunit @ active site but it has greater affinity and can still bind regardless of bacterial methylase
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what can you use if someone is resistant to other tetracyclines
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tigecyclin
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what is the metabolism of tetracyclines
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renal: tetracycline
hepatic: doxycycline, monocycline tetracycline may accumulate in bile |
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what unique metabolism event occurs with tetracyclines
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enterohepatic metabolism
therefore active drug will be active longer |
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what tetracycline can be used on complicated wounds
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tigecycline
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what can tigecycline be used to treat
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MRSA
vancomycin resistant enterococcus everything else tetracyclines treat |
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who must avoid use of tetracycline
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children under 8 or in utero
pregnant women |
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what are the adverse reactions of tetracycline
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photosensitivity
teeth discoloration suprainfection skin/muscous membrane rash |
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how does tetracycline cause teeth discoloration
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it is a chelator and binds to Ca+2 very tightly and will bind to it in our bones and enamel
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usually tetracycline can't be taken w/ dairy which ones can be take w/ dairy and what can't they be taken with
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monocycline and doxycycline can be taken with dairy but can't be taken with Mg+2, Ca+2 containing supplements, multivitamins, antacids
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what is the cause of a suprainfection
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take an antibiotic which changes the ecology of our natural flora and allows for other organisms resistant to that antibiotic to proliferate
this is an issue for tetracyclins |
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why is Chloramphenicol not always used
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due to it inhibiting mitochondrial protein synthesis as well leading to bone marrow suppression which can lead to:
neutropenia, thrombocytopenia, leukopenia, pancytopenia |
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where is chloramphenicol metabolized
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in liver via glucoronidation
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what is the mechanism of action of chloramphenicol
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binds to 50S subunit of bacterial ribosome (transpeptidation site) preventing the translocation of tRNA
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how are bacteria resistant to Chloramphenicol
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efflux pumps
bacterial enzymes acetylate chloramphenicol making it no longer able to fit into the binding site therefore altering the drugs affinity for 50S subunit |
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what macrolides can cause the post antibiotic effect
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azithromycin, clarithromycin due to them having high cellular and tissue levels (accumulation)
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if someone is resistant to a macrolide like erithromycin what macrolide can you give them
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none if you are resistant to one macrolide you're resistant to them all
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why can't macrolides, clindamycin, ketolides, cloremphenicol be given together
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they all bind to 50S and will have antagonist effect since they compete for same binding site
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what is the mechanism of action for macrolides
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bind to 50S preventing the translocation of tRNA
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what are the resistance mechanism for the macrolides
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efflux pumps
inactivation via esterase bacterial methylase methylate the 50S site on ribosome interfering w/ drug binding to subunit |
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what macrolide accumulate to high levels intracellularly
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azithromycin
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what macrolide accumulates to high levels in the tissue vs plasma
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clarithromycin
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what is the greatest therapeutic utility of macrolides
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upper respiratory tract infections
they also work on atypicals |
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what are the adverse reactions of macrolides
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most common: GI disturbances/diarrhea
most serious: cholestatic hepititis, arrhythmias |
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what are the macrolide drug interactions and give examples
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erythromycin and clarithromycin inhibit CYP3A4
warfarin, anticoagulants, valproic acid, carbemzapine, anticonvulsants, digoxin all use CYP3A4 |
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what is a synthetic analog of erythromycin
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ketolide, telithromycin
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what kind of bacteria are macrolides the best against
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atypicals
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what is the mechanism of action of ketolides
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bind to 50S subunit preventing tRNA translocation
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how are ketolides metabolized
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hepatically
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what is the best therapeutic use of ketolides
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Upper respiratory tract infection
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what is the MOA of Clindamycin
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binds to 50S subunit preventing translocation of tRNA
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what is the resistance mechanism of clindamycin
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enzyme modification via esterases
ribosomal methylation @ 50S inabiling clindamycin from binding NOT EFFECTED BY EFFLUX PUMPS |
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which would be the best choice to fight a anaerobic bacteria clindamycin of macrolides
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clindamycin
EXCEPT FOR WHEN DEALING W/ C. DIFFICILE WOULD CAUSE SUPRAINFECTION |
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proliferation of C. Difficile leads to what
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pseudomembranous enterocolitis (antibiotic associated diarrhea)
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why can't gentamicin be given w/ clindamycin, macrolide/ketolide, tetracycline, cloremphenical
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has 3 MOA all on the ribosome therefore it would interfere w/ all of these drugs
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what are the streptogramins
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Quinupristin/Dalfopristin
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what is quinupristin's MOA (streptogrammin B)
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irreversibly binds to same 50S site as macrolides
effects elongation |
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what is dalfopristins (streptogrammin A) MOA
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binds to a different site on the ribosome and enhances the binding of quinupristin
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what are the properties of Streptogramins
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inhibit CYP3A4
reserved use gram + coverage (MRSA/MSSA/vancomycin resistant enterococcus) IV ONLY |
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what is a lincosamide
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clindamycin
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what is a Oxazolidinones
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Linezolid
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what is the MOA of linezolid
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binds to 23S rRNA of 50S subunit preventing association of the two ribosomal units therefore interfering w/ protein synthesis
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what are the properties of Linezolid
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gram + coverage
reserved use for multidrug resistant bacteria can be used synergistically w/ macrolides |
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what can be used to treat carbuncle/furuncle/hair follicle infection
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mupirocin
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what is the mechanism of action of Mupirocin
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inhibits isoleucyl tRNA synthetase
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what are the properties of mupirocin
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useful for treating skin infections
bactericidal topical antibiotic |
