antibiotics Flashcards
what is the difference between a bacteriacidal vs a bacteriostatic drug
a bacteriocidal drug kills the bacteria bacteriostatic inhibits growth
when would you se a bacteriocidal drug
when you have an invasive infection such as bacteremia, menigitis, and bacterial endocarditis
when would you use a bacteriostatic drug
when the host defenses can be counted on to eliminate the bacteria
what are the four main methods of actions of antibiotics
cell wall inhibitors, protein synthsis inhibitors, nucleic acid synthesis, anti metabolites…folic acid inhibitors.
what type of bacteria would be most effected against the cell wall synthesis drugs
gram positive bacteria because they build more cell wall or peptioglycan.
what type of antibiotic is penicillian and how does it work
it is a cell wall inhibitor and it binds to the serine in the binding site of the PBP with its beta lactam ring and irreversibly blocks the active site so no cell wall cross linking can occure.
How does vancomycin work and how can cells be resistant
cell wall inhibitor, last line of defense bind to the two terminal d alanines of the penta peptide chain on NAM but resistive bacteria will replace the terminal d alanine with D lactate.
Name two protein synthesis inhibitors and how they work
chloramphenicol blocks the formation fo the peptide bond between the amino acids and erythromycin block translocation of tRNA from acceptor site to donor site.
how does rafampin work
nucleic acid synthesis inhibitor, inhibits RNA polymerase preventing RNA synthesis
how does metronidazole work
nucleic acid synthesis inhibitor, inhibit DNA topoisomerase to prevent supercoiling of DNA to properly fit inside of the bacterial cell
how does quinolones work
nucleic acid synthesis inhibitor causes breaks in bacterial DNA
what do sulfonamides and trimethoprim do
they both are antimetabolites that inhibit the production of folic acid needed for purine rings needed for DNA synthesis.
what are the advantages/disadvantages of narrow spectrum
avoids some of te destruction of the normal flora, but pathogen must e idintified for correct antibiotic.
what are the advantages/disadvantages of broad spectrum
high likelihood of effectiveness against an unidentified pathogen but may result in destruction of normal flora can cause C. diff or clostridium difficile colitis
what type of penicillin is broad spectrum
aminopenicillins active against gram positive as usual but also agasint some gram negative
