Antibacterials - Protein Synthesis Inhibitors Flashcards
What are the primary modes of use of aminoglycosides?
IV, IM, and Topical - Not Oral
What is a unique process of function of aminoglycosides?
Transported into the cell
binds to ribosomes causing multiple types of dysfunction: -stops initiation
-premature release
-mRNA misreading
What is the post-antibiotic effect?
Aminoglycosides stay within the bacteria causing effects long after the blood concentration levels decrease.
–Concentration Dependent Killing– Peak Levels
What kind of organisms are aminoglycosides used to treat?
Aerobic Gram Negative organisms
Such as E.Coli and Pseudomonas
–Severe Infections Only–
What are the three aminoglycosides commonly used?
Gentamicin
Tobramycin
Amikacin - used when resistant to the other two
What are side effects of using aminoglycosides?
Very Narrow therapeutic window. Nephrotoxicity. Ototoxicity - irreversible.
–Only used for severe infections due to side effects–
What is the common mode of resistance to aminoglycosides and why is Amikacin resistant?
Most common mode of resistance is modification of the drug once inside of the bacteria inactivating them.
However, Amikacin is resistant to that type of modification of the others, used if resistant to them.
What other class of antibiotics are used with Aminoglycosides to increase effectiveness against gram positive bacteria?
B-Lactams increase the penetration of Aminoglycosides. Synergistic effects.
How does the class of Tetracyclines work as an antibacterial?
They bind the 30S subunit of bacteria preventing the binding of tRNA. Bacteriostatic
What kind of bacteria are tetracyclines typically used for?
They have a broad spectrum, but due to lots of resistance use has been limited to Unusual infections as first line. -Rocky Mountain Spotted Fever -Lyme Disease -Chlamydia + Uncommon bacteria Alternate for Syphilis and Gonorrhea
What should you be aware of when taking tetracyclines?
All tetracyclines bind divalent cations, causing decreased absorbance and effectiveness.
Do not take Calcium supplements with tetracyclines.
What are unique side effects of tetracyclines?
Photosensative Rash
Discolor teeth in young children
Can cause C.Diff and Candida in GI
What is the most common type of resistance to tetracyclines?
Efflux Pumps that reduce the concentration inside the bacteria. If resistant to one kind of tetracycline, then resistant to all of them.
What are the two most common tetracyclines currently?
Doxycyline and Minocycline
Calcium binding: Doxycycline < Minocycline
What drug has a similar mechanism to tetracyclines, but is not in the class of tetracyclines?
Tigecycline - also binds additional sites in ribosome
If a patient is allergic to tetracyclines how susceptible are they do Tigecycline allergy?
There is no cross reactivity between tetracyclines and Tigecycline
What are the common types of uses for Tigecycline?
IV use Only
Skin Infections Complicated intra-abdominal infections Community acquired pneumonia Most Gram Positive and Negative --Does not work for pseudomonas--
What are side effects of Tigecycline?
SImilar to Tetracycline, even Calcium binding.
However, increased risk of death from serious allerigies.
–LAST LINE OF DEFENSE–
What antibacterial interferes with peptide bond formation on the 50S subunit?
Chloramphenicol