Antibiotics II Flashcards
What is an example of a carbapenam? What is it used for?
Imipenem.
Broadest of all antibacterials (except MRSA). Used mostly in ICUs where there is a high density of resistant organisms.
What is an example of a monobactam? What is it used for?
Aztreonam
Used for: gram (-) aerobic bacilli (ESPECIALLY PSEUDOMONAS). No gram (+) or anaerobes.
What is vancomycin used for?
Usually only MRSA, coagulase (-) staph, aminopenicllin-resistant enterococcus, oral utility against metronidazole-resistant C. difficile.
What does Daptomycin attack? What is it used for?
Forms a pore in the cell membrane.
Used for gram (+) cocci; used for VRE and VRSA.
What is the gram (-) version of Daptomycin? What is it used for?
Colistin.
Usually reserved for Pseudomonas species resistant to all other antibacterials.
What is a 1st generation fluoroquinolone? What is its mechanism?
Ciprofloxacin.
Inhibits DNA gyrase at low concentrations.
What is ciprofloxacin used for?
All gram (-) enterobactericeae, urinary pathogens resistant/allergic to conventional treatment.
What is a 2nd generation fluoroquinolone? What is its mechanism?
Levofloxacin.
Inhibits DNA gyrase at low concentrations, inhibits topoisomerase IV at high concentrations.
What is levofloxacin used for?
Same spectrum as 1st generation fluoroquinolones, with the addition of Strep. pneumoniae.
What is the mechanism of Metronidazole? What is it used for?
Under anaerobic conditions where there is lots of acid, it is reduced to an active free radical, which damages bacterial and certain protozoal DNA.
It’s used for all anaerobic (drug of choice of C. difficile), some protoxoa, H. pylori.
What is the drug of choice for C. difficile?
Metronidazole
What is the mechanism of Rifampin? What is it used for?
Inhibits DNA-dependent RNA polymerase to halt RNA transcription
Used for: mycobacterium tuberculosis and staph aureus.
What are two aminoglycoside/protein synthesis inhibitors? What are their mechanisms?
Gentamicin, tobramycin.
Inhibits 30S ribosome: forms a tight complex with ribosomal protein, causing codon-anticodon misreading and production of inactive proteins (bactericidal). Also inhibits initiation.
What are Gentamicin and Tobramycin?
Extremely effective against gram (-) rods, INEFFECTIVE AGAINST ANAEROBES due to an oxygen-dependent uptake mechanism.
What should you not take doxycycline with?
Milk and antacids (inactivates drug)
What is a tetracycline/protein synthesis inhibitor? What is its mechanism?
Doxycycline.
Inhibits 30S ribosome: blocks access of tRNA anticodon to its codon.
What is doxycycline used for?
Gram (+) (S. pneumoniae and MRSA), very effective against intracellular pathogens (mycoplasma, chlamydia, legionella, rickettsia).
What is the mechanism of Clindamycin? What is it used for?
Binds to 50S subunit at “A site”, which blocks peptide bond formation.
Used for all anaerobic bacteria (EXCEPT C. DIFFICILE), utility for pneumococci and MRSA.
What is an example of a Macrolide? What is its mechanism?
Azithromycin
Binds to 50S subunit and blocks translocation by interference with tRNA release following peptide bond formation (inhibiting the peptide exit tunnel).
What is Azithromycin used for?
Effective for intracellular pthogens (mycloplasma, chlamydia, legionella), H. influenza; utility for Gram (+) organisms
What is the mechanism of Linezolid? What is it used for?
Binds to 50S ribosome and inhibits peptidyl transferase.
Gram (+) organisms; used primarily for VRSA and MRSA
What do you use for aspiration pneumonia?
Clindamycin.
