intro to chemotherapy Flashcards
selective toxicity
greater toxicity to parasite than host
chemotherapy selects for what strains of bacteria
resistant strains
purpose of chemotherapy
lowers the microorganism load so that the host defense system can rid the body of foreign organisms
is maintenance of constant blood levels more important with bacteriostatic or bactericidal agents
bacteriostatic
what is vertical antimicrobial resistance
resistance to a drug is acquired by a mutation and passed vertically by selection to daughter cells
what are the three types of horizontal transfer of antimicrobial resistance
transduction, transformation, conjugation
transduction
DNA is transferred from one bacterium to another by a virus (bacteriophage)
transformation
bacteria undergo lysis all of the time and release DNA into environment. DNA is picked up by neighboring bacteria and incorporated into DNA
conjugation
required cell to cell contact; need sex pilus to join two cells together
list the drugs that are hepatotoxic
- tetracyclines
- isoniazid
- erythromycin estolate
- clindamycin
- sulfonamides
- amphotericin B
list the drugs that are renal toxic
- cephalosporins
- vancomycin
- aminoglycosides
- sulfonamides
- amphotericin B
which drugs have ototoxicity
- aminoglycosides
- vancomycin
- minocycline (vestibular only)
which drugs have visual toxicity
- ethambutol
- isoniazid
which drugs have photosensitivity
- tetracyclines
- fluoroquinolones
- sulfonamides
what is empirical antimicrobial therapy
diagnosis and choice of antimicrobial agent is based on clinical judgment and experience
bacteriocidal
cell death
bacteriostatic
growth inhibition
MIC vs MBC
- MIC: minimum inhibitory concentration
- MBC: minimum bactericidal concentration
concentration dependent killing
rate and extent of killing dependent upon drug concentrations
time dependent killing
killing is not increased with increasing concentrations above MBC, but is dependent on the time of exposure to the Abx
postantibiotic effect
persistant suppression of bacterial growth after limited exposure to an antimicrobial agent
abx synergism
when the inhibitory or killing effects of two or more antimicrobials used together are significantly greater than expected from thier effects when used inidividually
superinfections are most frequently observed with what type of Abx
broad spectrum antibiotics
what is the most common superinfection
intestinal candidiasis
- can be treated with oral nystatin or amphotericin B
staphylococcal enterocolitis is a superinfection that is life-threatening and should be treated how?
- discontinue abx therapy
- treat staph infection with oral vancomycin
pseudomembranous colitis is caused by what organism?
- clostridium difficile
