Antibiotics IIb Flashcards
which antibiotic is highly associated with c. diff infection?
clindamycin
does chloramphenicol exert a bacteriostatic or bacteriocidal effect?
bacteriostatic
chloramphenicol is mainly used for what infections?
typhus
rocky mountain spotted fever
what is the MOA of chloramphenical?
binds to 50S subunit and prevents transpeptidation or peptidyl bond formation
what are the key adverse effects of chloramphenicol?
blood - suppression of RBC production
gray baby syndrome
what is gray baby syndrome? what causes it?
infants lack glucuronic acid conjugation
chloramphenicol
linezolid is effective against what type of bacteria?
gram positive
what antibiotic is effective against organisms resistant to penicillin, methicillin, and vancomycin? why?
linezolid
check recording
what is the MOA of linezolid?
binds to P site of 50S subunit and inhibits formation of ribosomal-fMet-tRNA complex (step 1)
what is the key adverse effect of linezolid?
blood - myelosuppression
what is the only protein synthesis inhibitor agent that is not broad spectrum?
clindamycin
why dont the sulfonamides affect mammalian cells?
they depend upon exogenous folate and do not synthesize folate
what is the MOA of the sulfonamides?
structural similarity to PABA - precursor to dihydrofolic acid
compete with PABA for dihydropterase synthase and block dihydrofolate synthesis and thus DNA synthesis
what is the key adverse effect of sulfonamides?
skin
hypersensitivity
photosensitivity
steven johnson syndrome
trimethoprim agents target what type of bacteria?
gram negative
what is the MOA of trimethoprim?
inhibitor of BACTERIAL DHFR - impaired DNA synthesis
what is the key adverse effect of trimethoprim?
blood
bone marrow suppression
megaloblastic anemia
leukopenia
what combination of DNA synthesis inhibitor agents is used to treat UTIs and prostatitis?
trimethoprim-sulfamethoxazole (TMP-SMX)
what is the MOA of TMP-SMX?
synergistic
ciprofloxacin and levofloxacin are what class of abx?
fluoroquinolones - DNA synthesis inhibitor
what is the MOA of fluoroquinolones?
disrupt winding of DNA and separation of DNA strands during transcription and replication
specifically inhibit topoisomerase II (DNA gyrase) and topoisomerase IV
what are the key adverse effects of fluoroquinolones (eg cipro)?
GI - nausea, vomiting, diarrhea
drug nutrient interactions - bind divalent cations, prevent absorption (calcium)
CV - QT prolongation
what are the targets of group 2 fluoroquinolones? what are the group 2 fluoroquinolones?
- work well against gram negatives
- some activity against gram positive
ciprofloxacin, levofloxacin, ofloxacin
metronidazole is active against bacteria and what other type of organism?
protozoa
metronidazole is effective against bacteria with what property?
anaerobic
what is the MOA of metronidazole?
prodrug - undergoes activation inside organism - reaction metabolites bind to DNA and cause damage
what are the key adverse effects of metronidazole?
GI
metabolism - disulfiram effect (avoid alcohol)
what is the MOA of daptomycin? what is required for this action?
causes depolarization of membrane - bacteriocidal
calcium dependent
what are the key adverse effects of daptomycin?
musculoskeletal system - myopathy
what type of antibiotic is polymyxin B?
detergent
polymyxin B is typically combined with what other drug? for what purpose?
bacitracin
topical
why is polymyxin B effective?
sticks to LPS (gram negative)
what is the MOA of polymyxin B?
binds to phospholipids in the cell membrane and disrupts structure (punches holes), specifically LPS
