Antimicrobial Agents Flashcards
which are 30S inhibitors?
- aminoglycosides
- tetracyclines
which are 50S inhibitors?
- chloramphenicol
- macrolides
- lincosamides
- streptogramins
- oxazolidinones
- CLOMS
aminoglycosides bacteriostatic/cidal
- bactericidal
aminoglycosides used best against
- gram negative rods
aminoglycosides mechanism of action
- disrupt LPS in outer membrane
examples of aminoglycosides
- streptomycin
- gentamycin
S AND G IN aminoGlycoSide
aminoglycosides don’t work well against
- anaerobes are intrinsically resistant
aminoglycosides and pH
- reduced activity at low pH
enzymatically inactivate aminoglycosides
- modification by phosphorylation, adenylation or acetylation
- enzymes encoded on mobile genetic elements
alter drug target aminoglycosides
- methylation of rRNA
- mutation of ribosomal protein
alter drug exposure aminoglycosides
- decreased uptake nonspecific
- increased efflux (P. aeruginosa)
aminoglycosides and beta lactams
- beta lactams pre-weaken structure of bacterial envelope
- allows amino glycoside to get in
tetracycline bacteriostatic/cidal
- bacteriostatic
tetracycline used against
- gram positives
- gram negatives
- mycoplasma
- intracellular bacteria
tetracycline examples
- tetracycline
- doxycycline
CYCLINES
which has troubles with divalent cations
- tetracycline
- divalent cations inhibit absorption of drug in GI tract
which has contraindications
- tetracycline
- in pregnancy
- young children
- inhibition of bone growth
- discoloration of teeth
tetracycline and beta lactamases
- avoid!
- beta lactams will only work on actively dividing cells
- static interferes with the cidal activity
tetracycline alter drug exposure
- lots of efflux pumps
- most are effective against tetracycline itself
tetracycline alter drug target
- ribosome protection proteins
- bind to ribosome and displace drug from binding site
chloramphenicol bacteriostatic/cidal
- bacteriostatic
- cidal against important encapsulated organisms
- broad spectrum
- synthetic
chloramphenicol and ribosome
- binds 50S bacterial
- but not 60S human
chloramphenicol enzymatically inactivate drug
- modified by acetyl transferases
macrolides bacteriostatic/cidal
- bacteriostatic
macrolides work best against
- gram positives
- Chlamydia gram negative
POSITIVE THAT LIAR GAVE ME CHLAMYDIA WHEN HE ASSURED ME HE WAS NEGATIVE
LIE FROM MACROLIDE
macrolides examples
- erythromycin
- azithromycin
RO to RO
lincosamides bacteriostatic/cidal
- bacteriostatic
lincosamides work best against
- gram positive and gram negatives
- anaerobes
lincosamides example
- clindamycin
LINC TO CLIN
lincosamides used well against what pathogen
- C. diff associated pseudomembranous colitis
streptogramins A and B individually
- individually bacteriostatic
streptogramins A and B together
- bactericidal together
streptogramin A works against which process
- peptide bond formation
streptogramin B works against which process
- chain elongation
MLSB
- resistance to macrolides, lincosamides, and streptogrammin B
MLSB resistance
- cross resistance due to similar mechanisms of action
MlSB alter drug target
- ribosome methylation by erm genes
erm genes stand for
- erythromycin ribosome methylation genes
erm expression
- constitute or inducible
determine inducible clindamycin resistance
- use D test
- makes it look like a D on the plate
Oxazolidinones bacteriostatic/cidal
- bacteriostatic
Oxazolidinones work best against
- gram positives that are resistant to other antibiotics
Oxazolidinones bind to
- 23S in 50S subunit
Oxazolidinones cross resistance
- no cross resistance with other protein synthesis inhibitors
Oxazolidinones example
- linezolid
ZOLID ZOLID
Oxazolidinones alter drug target
mutations in 23S rRNA
folate synthesis inhibitors
- trimethoprim
- sulfonamides
RNA synthesis inhibitors
- rifamycin
- bind to DdRp wit higher affinity than human enzyme
DNA synthesis inhibitors
- fluoroquinolones
- target topoisomerase
- Cipro
agents that damage DNA
- nitroimidazoles
- form toxic free radicals
- Metronidazole
VanA locus
- constitutive resistance - all resistant or all susceptible when it burns out
- constant expression of D-Ala-D-lac
Van B locus
- inducible resistance - more of a spectrum of values for susceptibility
- temporary expression of D-Ala-D-lac
which costs more in terms of fitness - inducible or constitutive?
- constitutive
inhibit peptidoglycan synthesiis
- phosphomycin
- cycloserine
- bacitracin
- glycopeptides
- beta lactams
PROFESSOR CREWS GOES BEYOND BOARDS
agents that act on mycobacterial cell walls
- isoniazid
- ethambutol
isoniazid
- inhibits mycolic acid synthesis
ethambutol
- inhibits arabinotransferases
lipopeptides
- disrupt cell membrane of G+ bacteria
- poke holes in it
- daptomycin