Antibiotic Classes and Mechanisms of Action Flashcards
Name the 3 main groups of cell wall synthesis inhibiting antibiotics and their subclasses (if any)
1) Beta lactams: penicillins, cephalosporins and carbapenems
2) Glycopeptides: vancomycin
3) Fosfomycin
What types of proteins do beta lactams target? How do they work?
Penicillin binding proteins such as transpeptidases: essential enzymes involved in cell wall synthesis. Beta lactams work by binding competitively to PBPs against the D-ala-D-ala end of the penta peptide of cell wall subunit
Name the main glycopeptide antibiotic, type of bacteria it works on and its mechanism of action
Vancomycin is a cell wall synthesis inhibitor effective against gram positive bacteria only. It works by binding to the terminal d-ala of the pentapeptide, sterically hindering its addition into the cell wall.
In what 2 bacteria is vancomycin resistance the greatest concern and how has the resistance envolved?
Enterococcus and S. aureus. Resistance through substitution of d-ala for d-lac: vanco can’t bind
What is the spectrum of activity for vancomycin?
Gram positive cocci: MRSA, coagulase negative staph, penicillin resistant S. pneumo and enterococcus.
Gram positive bacilli: C. jeikeium and C. diff
What type of antibiotic are fluoroquinolones, what is the mechanism of action and what kinds of infections are they used for?
DNA synthesis inhibitors. They target DNA gyrase and topoisomerase 4, preventing re-annealing of DNA strands during synthesis. Useful for treating gram negative infections, atypicals and complicated UTIs
What is the mechanism of action of metronidazole? What types of infections is it used for?
Inhibits DNA synthesis by disrupting and damaging DNA. It is used to treat anaerobic infections, C diff
What are the 3 classes of protein synthesis inhbiting antibiotics?
Macrolides, lincosamides and streptogramins
Tetracyclines
Aminoglycosides
What are the 3 classes on the macrolides and their mechanism of action? What kinds of infections are they used to treat?
Erythromycin, clarithromycin and azithromycin. Work by binding to the 50s ribosomal subunit and blocking protein synthesis. Used to treat CA pneumonia, pertussis, and atypicals (mycoplasma/chlamydia)
What are the 3 tetracyclines? What is their mechanism of action and what kinds of infections are they used to treat?
Tetracycline, doxycycline, minocycline. Inhibit protein synthesis by binding to the 30s ribosomal subunit. Used to treat atypical infections, animal borne (yersinia, brucella, burgdorferi, rickettsiae)
What is a commonly used aminoglycoside? What is their mechanism of action? What kind of infections can they NOT be used to treat and why?
Tobramicin. Binds irreversibly to the 30s ribosomal subunit. Don’t work in anaerobic environments (abscesses) because it uses O2-dependent transport to get into the cell.
Why do aminoglycosides require therpeutic drug monitoring?
Because they can inhibit mammalian protein synthesis at high concentrations causing ototoxicity and nephrotoxicity
What types of infections can aminoglycosides be used to treat?
Complicated UTIs, pseudomonas and resistant gram negative bacilli
What is the antibiotic combination used against bacterial metabolism? What types of infections can it be used to treat?
TMP/SMX: trimethoprim and sulfamethoxazole. Blocks folic acid synthesis at 2 points. GI, very active anti-staphylococcal agent.
