Antimicrobials 2 Flashcards
What is the difference between ribosome weight in prokaryotes vs. eukaryotes?
30S + 50s= 70s bacteria
40s + 60s= 80 s humans
Name two things that attack the 30s subunit
tetracyclines
aminoglycosides
Name 5 things that attack the 50s subunit
Macrolides Clindamycin Linezolid Chloramphenicol Streptogramins
Name one thing that attacks the tRNA sythetase
mupirocin
Bacteria mRNA is ….while eukaryotic mRNA is….
polycistronic
monocistronic
What is the first amino acid in the polypeptide of prokaryotes?
fMet
What initiation factors are required for prokaryotes? Releasing factors?
IF1, IF2, IF3
RF1, RF2, RF3
How many initiation factors are required for eukaryotes? Releasing factors?
9, 1
What happens to the methionine when the translation is done?
Prokaryotes: the f is chopped off, met stays
Eukaryotes: the met is chopped off
What does chloramphenicol do?
Binds 50s part, inhibits formation of peptide bond
What does Erythromycin do?
Binds 50s part, prevents translocation
What do tetracyclines do?
Interfere with the tRNA and mRNA attachment
What does streptomycin do?
Changes the shape of the 30s portion, causing the mRNA code to be read incorrectly.
Streptomycin is an
aminoglycoside
Erythromycin is a
macrolide
What are the aminoglycosides?
gentamicin amikacin tobramycin, streptomycin neomycin (bind 30s and block initiation, prematurely terminate, and cause misreading)
Aminoglycosides: cidal or static? concentration dependent or time? what do they treat? Example? IV or oral? metabolized? Synergy with?
cidal concentration dependent treat gram - aerobes Streptomycin treats TB IV or IM, NOT oral (but neomycin is topical) not metabolized (polar, won't cross BBB) Synergy with b lactase or vancomycin
Adverse effects of aminoglycosides
ototoxicity nephrotoxicity neuromuscular paralysis Contact dermatitis (don't give to elderly, kidney patients)
What is the oldest amino glycoside drug? How is it administered?
Streptomycin,
IM, IV
Has high level of bacterial resistance
What is the most commonly used amino glycoside drug?
Gentamycin (IV)
What is the broadest spectrum of all aminoglycosides?
Amikacin (IM, IV)
What amino glycoside has excellent activity against Pseudomonas aeruginosa?
Tobramycin (IM, IV)
What amino glycoside is only applied topically because of its toxicity? (Good for enemas too)
Neomycin
What are the 4 tetracyclines?
Tetracycline, Doxycycline, minocycline, tigecycline
What are Tetracyclines good against?
LOTS! G+, G-, and atypical weirdos like rickettsia, mycoplasma and chlamydia
How do Tetracyclines work?
Bind to 30s blocking tRNA and mRNA. This is Type 3, time dependent killing. So you want to maximize amount of drug
Tetracycline is the 1st drug of choice against
Rickettsia, mycoplasma, and chlamydial infections, brucellosis, cholera, and Lyme disease and plague
Tetracycline is the 2nd dug of choice against
mixed infections of the respiratory tract and acne
Which tetracycline is effective even when others are not?
Tigecycline
What are the side effects of tetracycline
Every problem ever (liver, sun sensitive, tooth staining, itchy bottom, etc) and hairy tongue
When is tetracycline contraindicated?
pregnant patients, kids under 8, liver and renal disease
Is tigecycline effective against bacteremia?
No. (Bile/fecal excretion)
What are the three macrolides?
Erythromycin, clarithromycin, azithromycin
Macrlolides: Mechanism? Static or tidal? What type of dependency? Broad or narrow spectrum? Safe or risky?
Binds 50s and prevents translocation Static Type II (time dependent) Broad spectrum, G+ and G- and atypical bacteria One of the safest antibiotics
How is Azithromycin better than Erythromycin?
Less active against staph and strep, but more active against respiratory infections like H. Influenzae, Moraxella, and Mycobacterium (Not TB).
What is Azithromycin the drug of choice against?
urethritis caused by Chlamydia.
How do macrocodes get taken in and where to they get distributed, metabolized, excreted etc?
Taken orally, (food hinders most but helps clarithro)
Goes to all body fluids except CSF
Metabolized in liver (can make other drugs concentrate because all but Az pack inhibit CYP450 enzymes.) Az has longest half life and volume distribution.
Excreted: Ery and az in bile. Clarithro: kidney and liver.
Chloramphenicol: Mechanism, spectrum, Clinical use, PK, adverse effects
Mech: inhibits peptidyl transferase reaction to stop peptide bond and protein synthesis
Spectrum: Broad. G+,G-, anaerobes and rickettsia
Uses: ONLY life threatening H. Influenzae, bactericides, and meningitis when penicillin can’t be used (toxicity!!)
PK: IV or oral. Goes everywhere including CSF
Adverse effects: hemolytic anemia, aplastic anemia, gray baby syndrome, teratogen, serious drug interactions
Clindamycin is a
LIncosamide
Clindamycin mechanism, spectrum, PK, adverse effects, clinical uses
Mech: same as macrocodes
Spectrum: anaerobes, non-enterococcal G+, NO G-
PK: oral, IV, IM, doesn’t got to CSF
Adverse effects: pseudomembranous colitis. Treat that with vancomycin or metronidazole.
Clinical uses: good orally or parenterally
Linezolid: mechanism, spectrum, PK, Clinical uses, Adverse effects
Binds 50s to prevent ribosomal complex formation
Good against all G +, aerobic or an. Not G-.
Bactericidal against streptococci, static against Enterococci and Staphylococci
Uses: VRE, nosocomial pneumonia (MRSA), CA Pneumonia, skin infections, staph strep and MRSA.
Side effects are very rare. Causes suppression of WBCs in some. Serotonin syndrome. Chronic use has reversible neurotoxicity (peripheral and optic)
Quinuprostin/Dalfopristin are
Streptogramins
Quinuprostin/Dalfopristin mechanism, spectrum, PK, Clinical uses, Adverse effects
Binds 50s, stops translocation.
Synergistic, bactericidal
Kills all G+, but no G- except moraxella and neisseria
PK: no dose adjustment needed in renal insufficiency
Reserve for serious infections by resistant G+
Adverse effects: pain at injection site, arthralgia and myalgia
Mupirocin (Bactroban) mechanism, spectrum, PK, Clinical uses, Adverse effects
Reversibly inhibits isoleucyl transfer-RNA synthetase enzyme. Bactericidal against G+ and some G- PK: topical Clinical uses: skin infections Avoid eyes
