Antibiotics Flashcards
what are the different types of antimicrobial chemotherapy
antibacterial, antiviral, anti fungal, antiparasitic
what are the majority of antibiotics based on
naturally occurring compounds or may be semi-synthetic or synthetic
what does differential toxicity refer to
antimicrobial chemotherapy, based on the concept that the drug is more toxic to the infecting organism than to the host
do we want a drug to be narrow or broad
as narrow/direct to the organism as possible
what is the minimum inhibitory concentration (MIC)
the minimum concentration of antibiotic required to inhibit the growth of the test organism
what is the minimum bactericidal concentration (MBC)
the minimum concentration of antibiotic required to kill the testosterone organism
what is bacteriostatic
inhibit growth
antimicrobial keeps growth static when antimicrobial is removed the growth increases again
what is bactericidal
kills growth
when antimicrobial is added it keeps killing the microbe until you remove the drug
what is the goal of concentration dependent killing
maximize concentration so the drug can be dosed less frequently (1 or 2 times a day)
what is the goal of time dependent killing
maximize exposure
keeping the drug above MIC as long as possible, have to dose my frequently though
what is prophylaxis
antimicrobial agents are administered to prevent infection (ex. surgical prophyaxis so no bacteria gets into the body upon initial cut)
what is the ideal antibiotic
no/low toxicity to the host
low propensity for development of resistance
does not induce hyper-sensitives in the host
Rapid and extensive tissue distribution
relatively long half life (dose less frequently)
free of interactions with other drugs (ex. old people take a lot of drugs that could interact)
Convenient for administration/relatively inexpensive
what are the beta lactams
- beta lactams
- penicillins
- cephalosporine
- carbapenems - glycopeptides (vasomycin)
- fosfomycin
what is beta lactam resistant
- from beta lactamase, it opens the beta lactam ring and makes it unable to bind to the pbp, so no cross linking enzyme (transpeptidase)and weaken cell wall
- target site/pbp modification
- altered permeability (gram-negs outer membrane so cant get in)
how do you inhibit beta lactam
add an antibotic with a beta lactamase attached to it to prevent the ring from breaking
clavulanic acid
tazobactam
what are cephalosporins
part of the beta lactams
they have 5 generations
gen 1 is for gram positive - get 5 is for gram neg
what are cerbenenems
part of beta lactams
used to treat severe illness
what are glycopeptides
the only drug is vasomycin
it binds to the peptidoglycan directly and makes it too big to fit into the pbp
only works with gram positives
1% of the time administered orally for C. difficile so goes directly to the gut
what are glycopeptide reistsances
enterococcus makes d-lac instead of a-ala which is able to dind to the pbp so there is no cross linking (transpeptidase) and a weak cell wall
what type of drugs require therapeutic drug monitoring
gycopeptides (vasomycin) and aminoglycosides
what is fosfomycin
a type of beta lactam
old drug that has been brought back
used to treat UTIs
works in the cytoplasm to prevent the organism from synthesizing the building blocks requires to make peptidoglycan (cell wall)
Drug is only taken once
fluoroquinolones
distrupt DNA synthesis
Bind to DNA gyrase and Toposisonmerase IV
DNA gyrase can unwind but cannot recoil together
explain fluroroquinolone resistance
- mutation: of parC and gyrA, changes AA and reduces affinity for the drug to bind
- increase in efflux pumps
- decrease in porins cant get in
what are the antibiotics that disrupt the protein sythesis
- macrolides
- clindamycin
- tetracyclines
- aminoglycosides
all work by binding to ribosome and inhibiting protein synthesis
