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71 Cards in this Set
- Front
- Back
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Name 9 drugs that inhibit bacterial protein synthesis.
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AMINOGLYCOSIDES
TUBERCULOSIS TETRACYCLINES CHLORAMPHENICOL CLINDAMYCIN MACROLIDES MUPIROCIN STREPTOGRAMINS LINEZOLID |
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Which antibacterial inhibits protein elongation?
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Tetracycline
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Which antibacterials inhibit protein peptidyl transferase?
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Chloramphenicol
Clindamycin |
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Which antibacterials inhibit protein translocation?
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Erythromycin
Quinurpristin/dalfopristin |
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What are the three mechanisms by which aminoglycosides inhibit protein synthesis?
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Blocks synthesis initiation
Blocks further translocation and elicits premature termination Causes incorporation of wrong aa's |
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Route of Gentamicin? Why?
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IV or IM because it has many charged NH groups
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Excretion of Gentamicin? Consequence of this?
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Excreted unchanged by kidneys
Dose must be adjusted if there is evidence of renal failure (there's graphs vs creatinine clearance) |
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What are the adverse reactions of Gentamicin?
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Nephrotoxicity
Ototoxicity (Vestibular, Cochlear) Neuromuscular blockade |
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Rank the aminoglycosides in order of nephrotoxicity.
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Kentamycin & Neomycin >Streptomycin>Gentamicin
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Why are aminoglycosides nephrotoxic?
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They bind proximal tubular cells and become internalized, damaging the brush border (letting enzymes leak out) and disrupt membranes
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What's important to know about the ototoxicity associated with aminoglycosides?
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It can be very severe and irreversible.
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How do aminoglycosides cause a neuromuscular blockade?
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They block both the release of ACh and the receptors
(Very serious, can accentuate myasthenia graves) |
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What are the clinical uses of streptomycin?
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Second line drug in Rx tuberculosis
Tularemia, plague More toxic than newer agents |
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What are the clinical uses of gentamicin, netilmicin, and tobramycin?
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Serious Gm(-) infects like Pseudomonas, Enterobacter, Klebsiella, Serratia
Undefined sepsis, enterococcal endocarditis, pneumonia, meningitis |
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What are the clinical uses of neomycin?
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Topical ointments
Sterilization of the bladder to prevent infection promoted by indwelling catheters |
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Name the 6 aminoglycosides.
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streptomycin
gentamicin netilmicin tobramycin neomycin amikacin |
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What are the clinical uses of amikacin?
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Clinical uses similar to Gentamicin
Resistant to bacterial enzymes that inactivate aminoglycosides |
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What are the 3 ways bacteria build a resistance to aminoglycosides?
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Acetylation
Produces kinases to phosphorylate Adenylation |
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Why is it helpful to combine penicillin and an aminoglycoside when treating an enterococcus infection?
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Alone, penicillin can inhib the cell wall but won't kill the bacteria and aminoglycoside can't enter to get to it's site of action at the ribosomes. Together, aminoglycosides can enter through the damaged cell wall caused by penicillin = cell death!
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What is first line therapy in the treatment of m. tuberculosis?
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Isoniazid + Rifampin + Pyrazinamide + Ethambutol
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What is first line therapy in the treatment of M. avium?
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Clarithromycin + Ethambutol
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What is first line therapy in the treatment of M. leprae?
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Dapsone + rifampin ± clofazimine
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Mechanism of action of Isoniazid?
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Inhibits synthesis of mycolic acid (used in the cell wall of mycobacterium) via inhibition of 24:1 cis-5 elongase
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What is the mechanism of action of ethambutol?
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Inhibits mycolic acid transport to the outside of the cell, disrupting the mycobacterial cell envelope.
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How does the body metabolize Isoniazid?
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Acetylated to inactive form in the liver
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What are the main adverse reactions with Isoniazid?
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Hepatitis, rash, allergies
Neuropathies - pyridoxine deficiency |
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What are the main adverse reactions with ethambutol?
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Optic neuritis & G.I. distress
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What are the main adverse reactions with Pyrazinamide?
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Hepatotoxic
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What is the mechanism of action of Pyrazinamide?
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Bactericidal - unknown mechanism
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What is the mechanism of action of Rifampin?
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Inhibits RNA polymerase
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What is the spectrum of Rifampin?
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Broad spectrum but Resistance occurs so you most often use in combo with other drugs
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What is the main side effect of Rifampin?
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Induces Cyt. P450
Also has colored metabolites |
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What is the mechanism of action for tetracyclines?
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Bacteriostatic: bind the 30S ribosome and prevent the binding of tRNA to the A site on the 50S, blocking translocation
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What is the spectrum of tetracyclines?
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Broad spectrum drugs
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What is the elimination method for tetracyclines? What's note with regards to absorption?
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Renal and hepatic elimination
Can form stable chelates with several metal ions. Absorption of oral doses is reduced by calcium (milk), magnesium hydroxide or aluminum hydroxide (antacids) or iron |
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What are the adverse reactions with tetracyclines?
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GI distress
Nephrotoxicity Stains teeth, bones Photosensitivity |
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What is the mechanism of action of Dapsone?
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Bacteriostatic, blocks folic acid synthesis
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What the clinical use of Dapsone?
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Used in combination with Rifampin to tx leprosy.
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What is the mechanism of action of clofazimine? Side effect?
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Unknown, bacteriocidal. Also anti-inflammatory.
May cause skin discoloration |
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What is the clinical use of Clonfazimine?
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Used in the tx of leprosy.
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What is the mechanism of action of Chloramphenicol?
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Bacteriostatic: inhibits protein synthesis by binding to the 50S of the bacterial ribosome, distorting it so that the peptide bond doesn't form
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What is the spectrum of Chloramphenicol?
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Broad spectrum, very active drug
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What are the adverse reactions of Chloramphenicol?
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Gray baby syndrome (babies can't metabolize the drug)
Reversible, dose-dependent bone marrow suppression (*inhibs mitochondrial protein synthesis) Aplastic anemia |
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What are the clinical uses of Chloramphenicol?
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Restricted to life threatening infections. Should be used when other drugs fail if it is superior to all other alternatives.
Primary indications - typhoid fever, bacterial meningitis, eye infections |
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What's important when using Chloramphenicol?
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Leukocyte and differential count should be taken to monitor bone marrow function
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What is the spectrum of Clindamycin?
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Narrow spectrum – Staph., Strep, anaerobes
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What are the clinical uses of Clindamycin?
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Mixed infections
Anaerobes: Clostridium, B. fragilis |
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What are the adverse reactions of Clindamycin?
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Gastrointestinal distress
Antibiotic-induced colitis |
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What is the mechanism of action of Clindamycin?
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Bacteriostatic: inhibits protein synthesis by binding to the 50S subunit of the bacterial ribosome and blocking peptide bond formation
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What is the mechanism of action of macrolide antibiotics?
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inhibits bacterial protein synthesis by binding to the 50S subunit of the ribosome, preventing translocation
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Name the 3 macrolide antibiotics.
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Erythromycin
Azithromycin clarithromycin |
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What is the spectrum of macrolide antibiotics?
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Narrow spectrum:
Good activity against Gm (+) cocci and bacilli H. influenzae Legionella pneumophilia Mycobacterium avium H. pylori |
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What are the adverse reactions of macrolide antibiotics?
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GI distress
Allergic reactions Inhibits Cytochrome P450 |
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What is the mechanism of action of Mupirocin?
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binds to isoleucyl t RNA synthetase and prevents incorporation of isoleucine into proteins
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What is the spectrum of Mupirocin?
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Narrow spectrum - Staph., Strep
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What's the clinical use of Mupirocin?
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Used in treating impetigo
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What are the adverse reactions of Mupirocin?
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local irritation
pain at site of application |
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What is Quinupristin/dalfopristin? What's its mechanism?
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Bactericidal: Combination of an A and B strepto-gramins bind bacterial ribosomes and inhibit protein synthesis
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What is the spectrum of Quinupristin/dalfopristin?
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Relatively selective coverage of gram-positive aerobic bacteria
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What are the adverse reactions associated with Quinupristin/dalfopristin?
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Infusion-site inflammation, pain, and edema
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What antibiotics should be avoided in pregnancy? (7)
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Aminoglycosides
Clarithromycin Erythromycin estolate Fluoroquinolones Tetracyclines Sulfonamides (used in the third trimester) Metronidazole |
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Why should Aminoglycosides be avoided in pregnancy?
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They have caused ototoxicity in the developing fetus
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Why should Clarithromycin be avoided in pregnancy?
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embryotoxic based on animal studies
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Why should Erythromycin estolate be avoided in pregnancy?
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increases the incidence of cholestasis in the pregnant patient
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Why should Fluoroquinolones be avoided in pregnancy?
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They have deleterious effects on collagen metabolism in animals
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Why should Tetracyclines be avoided in pregnancy?
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They interfere with bone and tooth formation via calcium chelation
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Why should Sulfonamides be avoided in pregnancy?
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They may displace bilirubin from plasma proteins in the fetus and neonate causing kernicterus
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Why should Metronidazole be avoided in pregnancy?
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mutagenic in the Ames test
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What antibiotic therapy is recommended for the treatment of bacterial endocarditis?
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Ampicillin + nephacillin + Gentamicin
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What is the clinical use of Oxazolidinone (Linezolid)?
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Treatment of vancomycin-resistant enterococcus (VRE), nosocomial pneumonias (S. aureus, S. pneumoniae), skin infections (S. aureus)
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What are the adverse reactions of Oxazolidinone (Linezolid)?
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n/v/d, potential thrombocytopenia, and neutropenia in patients susceptible to bone marrow toxicity
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