Flashcards in Micro 15 - Protein Synthesis Inhibitors Deck (33)
What is the mechanism of action of Linezolid?
Binds to 23S RNA and interacts with the bacterial initiation complex.
In what clinical cases do we use Linezolid?
MRSA (Methicillin Resistant Staph Aureus) and VRE (Vancomycin Resistant Enterococci). Used orally (outpatient).
What is the mechanism of action of Tetracycline?
Binds to the 30s and prevents attachment of aminoacyl-tRNA. They are bacteriostatic and limited CNS penetration.
What are 4 commonly used tetracyclines?
Tetracycline, doxycycline, demeclocycline, minocycline.
How is Doxycycline eliminated?
Fecally, so it can be used in patients with renal failure.
What are the clinical uses for tetracyclines?
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Vibro cholerae, Acne, Chlamydia, Ureaplasma urealyticum, Mycoplasma pneumoniae, Tularemia, Helicobacter pylori, Borrelia burgdorferi, Rickettsia.
What substances must be avoided when taking tetracyclines?
Milk, antacids, Iron, calcium and magnesium.
What are the side effects of tetracyclines?
GI distress, Discoloration of teeth in children, Inhibits bone growth in children, photosensitivity.
What are the three medications that can cause photosensitivity?
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Sulfonamides, Amiodarone, Tetracycline.
What are 5 commonly used aminoglycosides?
Getamicin, Neomycin, Amikacin, Tobramycin, Streptomycin.
What is the mechanism of action of aminoglycosides?
Binds the 30s Ribosome. Bactericidal. Inhibits the formation of the initiation complex and causes misreading of mRNA.
What is the weakness of aminoglycosides?
It requires oxygen to work, therefore ineffective against anaerobes.
What are the clinical uses of Aminoglycosides?
Severe G(-) rod infections. They work synergistically with beta-lactam antibiotics (ampicillin with gentamicin in neonatal infections). Neomycin is used in Bowel surgery.
What are the side effects of aminoglycosides?
Nephrotoxicity (esp when used with cephalosporins). Ototoxicity (esp when used with loop diuretics). Teratogenic.
What are 3 commonly used macrolides?
Erythromycin, Azithromycin, Clarithromycin.
What is the mechanism of action of macrolides?
Inhibits protein synthesis by blocking translocation. It binds to the 23s rRNA of the 50s ribosomal subunit. Bacteriostatic.
What are the clinical uses of macrolides?
Pneumonia (atypical), URI (strep pneumo, strep pyogenes), STD (chlamydia, gonorrhea). Safe in pregnancy.
What are the side effects of Macrolides?
Prolonged QT interval, GI discomfort, Rarely acute cholestatic hepatitis (w/ erythromycin estolate)., rare cases of eosinophilia.
What are some drug interaction of macrolides?
Increase serum concentration of theophylline. Oral anticoagulants (e.g. Warfarin).
What is the mechanism of resistance against macrolides?
Methylation of the 23 rRNA binding sire.
What is the mechanism of action of chloramphenicol?
Inihibits the 50s peptidyltransferase activity. It is bacteriostatic.
What are the clinical uses of Chloramphenicol?
Meningitis by H.influenzae, N.meningitidis, S.pneumoniae.
What are the side effects of chloramphenicol?
Gray baby syndrome (because premature infants lack liver UDP-glucoronyl transferase, very important in degrading chloramphenicol), anemia (dose dependent), aplastic anemia (dose dependent).
What are the symptoms of gray baby syndrome?
Buildup of toxic metabolites of chloramphenicol, vomiting, ashen gray color of the skin, poor muscle tone, cyanosis, CV collapse.
What is the treatment for Gray baby syndrome?
Stop chloramphenicol, exchange transfusion, phenobarbital (induces the production of UDP-glucoronyl tranferase).
What is the mechanism of action of Clindaymycin?
Blocks peptide bond formation with the 50s ribosomal subunit. Bacteriostatic.
What are the clinical uses of Clindamycin?
Anaerobic infections, MRSA infections, Protozoal infections, Topically for treating acne. For bacteriodes fragilis and Clostridium perfringens. Skin abscess that are caused by MRSA can be treated by oral clindamycin.
What are the side effects of clindamycin?
What is the mechanism of action of streptogramins (Quinupristin/Dalfopristin (Synercid))?
Act by bind to the 23s portion of the 50s ribosome.