50S Protein Synthesis Inhibitors - Fitzpatrick Flashcards
(31 cards)
Macrolides - drugs (3)
- Erythromycin
- Clarithromycin
- Azithromycin
Ketolides - drug (1)
Telithromycin
Erythromycin - treats what?
In respiratory medicine, used when?
- Gram (+) cocci (Staph, Strep)
- SYPHILIS (treponema pallidum)
If Penicillin allergy - for strep throat, strep. pneumonia, etc.
Clarithromycin - treats what?
- Gram (+) cocci (NOT MRSA)
- Some gram (-)
- Chlamydia, Legionella, Moraxella
Azithromycin - DOC for what?
Legionella (Legionnaires’ disease)
Telithromycin (Ketolide) - DOC for what?
Multi-drug resistant Strep. Pneumoniae
A major indication for Macrolide/Ketolides = _______
URI’s, community acquired pneumonia
TYPICAL respiratory infection organisms covered by Macrolides
- Strep. pneumonia
- Haemophilus
- Moraxella
ATYPICAL respiratory infection organisms covered by Macrolides
- Legionella
- Chlamydia
- Mycoplasma
Most commonly used Macrolide? Why?
Azithromycin - long half life, effective, additional gram (-) coverage
Macrolides - MoA
Bind 50S ribosome, inhibit translocation of growing peptide along the ribosome to make room for next tRNA
Mechanisms of resistance to Macrolides (2)
- Methylation of ribosome (“erm” genes) - MORE resistant
- Macrolide efflux pumps (“mef” genes) - PARTIAL resistant
Organisms naturally resistant to Macrolides
Why?
- Enterobacter
- Pseudomonas
- Acinetobacter
Decreased permeability of outer cell envelope
Adverse effects of Macrolides/Ketolides
- QTc prolongation (blocking inward rectifying K+ channels)
- CYP 3A4 drug interactions
_____ is most associated with increased risk of sudden cardiac death due to QT prolongation / Torsades
This risk is increased in who?
Erythromycin
Pt’s taking CYP 3A4 inhibitors –> Erythromycin around longer
A pregnant woman needs a Macrolide for a respiratory infection. Which ones?
Erythromycin, Azithromycin
Clindamycin - drug class
Lincosamides
Clindamycin is similar to ____ in terms of MoA, resistance mechanisms, and usage w/ gram (+) cocci
Erythromycin
Clindamycin - clinical uses (main ones) (2)
- Abdominal ANAEROBES - MAIN ONE (Ex. B. fragilis via gunshot/stab)
- Toxin-producing bacteria (toxic shock syndrome, PVL toxin, SEB toxin, etc.)
Adverse effect of Clindamycin
C. diff. overgrowth –> pseudomembranous colitis
Treatment of Clindamycin-induced C. Diff. infection
Metronidazole + Vancomycin ORALLY (not absorbed)
When might Clindamycin be used WITH a Beta-Lactam? Why?
At FIRST glance, why might this be counterintuitive?
An infection that is secreting a damaging toxin of some kind
- Clindamycin –> inhibits protein synthesis –> inhibits TOXIN synthesis
NORMALLY, not good to combine a bacteriocidal w/ a bacteriostatic (exception in this case)
Chloramphenicol - spectrum?
WIDE spectrum (Gram + and Gram -)
Chloramphenicol - clinical use?
Almost none - life-threatening infections w/ no alternative
