Test 3: 37 antibiotics part 2 Flashcards
how does B lactams work
inhibit transpeptidase enzymes from forming crosslinks between peptidoglycans in the cell wall
peptidoglycan is a rigid mesh of cross linked —
glycopeptides
TPase forms cross bridges between chains
β lactam antibiotics (penicillin, cephalosporins) inhibt TPase from working
some bacteria make — that makes them resistant to penicillin
β lactamase
acts as a PBP (peniciilin binding protein)
will bind to penicillin and change its structure so it can not bind to Transpeptidase enzyme and stop crosslinking of PG in the cell wall
how to prevent βlactamase resistance
some semi synthetic penicillins are resistant (dicloxacillin and oxacillin)
synthetic β lactams such as Monobactam
use combo of drugs (clavamox)
how does clavamox prevent resistance by β lactamases
combo of
Amoxicillin (SS, broad spectrum, β-lactamase sensitive)
Clavulanic Acid (β-lactamase inhibitor)
vancomycin
bactericidial- attack cell wall ( D-Ala and inhibit cross linking)
gram + only
2nd line defense against peniciilin resistant S. aureus
poorly absorbed- given IV
— binds to the free D-Ala-D-Ala end of the Pentapeptide and inhibits cross-linking by steric hindrance.
Vancomycin- gram + bactericial antibiotic
Vancomycin does not affect the catalytic activity of the transpeptidase.
mechanism of action for bacitracin
bactericial (Gram + > Gram -)
Prevents dephosphorylation of a Lipid carrier during glycopeptide transfer through the cell membrane required for cell wall synthesis
poorly absorbed in the gut (topical use)
bacitracin prevents — of a Lipid carrier during glycopeptide transfer through the cell membrane required for cell wall synthesis
dephosphorylation
prevents P from breaking off and opening P up for binding to chains and moving them out onto the cell surface
bactericial (gram +» gram -)
cycloserine is used to fight —
Mycobacterium tuberculosis and Mycobacterium avium
how does cycloserine work
Cycloserine prevents addition of the two terminal D-Alanines to the Tripeptide side chain attached to NAM
Cycloserine prevents addition of the — to the Tripeptide side chain attached to NAM
two terminal D-Alanines
cycloserine- broad spectrum (Mycobacterium tuberculosis)
The — block cross-linking by inhibiting the
transpeptidase.
β-lactams
penicillin + cyclosporins
Combat β lactamase by using — drugs or by combinations of drug
Semi- or fully synthetic β- lactamase-resistant
Vancomycin inhibits cross-linking by —
steric hindrance
binds to DAla and prevents TPase (transpeptidase) from forming cross bridges
— inhibits dephosphorylation of the carrier lipid in the cell wall
Bacitracin
bactericidal: gram +» Gram -
Cycloserine prevents — addition
D-Ala-D-Ala
Cycloserine prevents addition of the two terminal D-Alanines to the Tripeptide side chain attached to NAM
bactericidial broad spectrum (Mycobacterium tuberculosis)
Fluoroquinolones (inhibit — synthesis)
DNA
Rifamycins (inhibit — synthesis)
RNA
how is RNA made
RNA polymerase binds to DNA and makes RNA
— allows for unwinding of DNA
topoisomerase II (DNA gyrase)
what are some fluroquinolines
Enrofloxacin, Difloxacin, Orbifloxacin and Marbofloxacin.
bactericidal ( broad gram - spectrum, narrow Gram + (staph))
inihibit DNA synthesis
mechanism of action for fluoroquinolines
Fluoroquinolones bind to the nicked DNA and TI-II (Topoisomerase II/ DNA gyrase) And prevent the re-sealing of DNA and subsequent replication And re-supercoiling.
Enrofloxacin, Difloxacin, Orbifloxacin and Marbofloxacin.
Bactericidal (Broad G- Spectrum; Selected G+ (e.g. some Staph))
mechanism of action for rifamycin
Binds and blocks bacterial RNA polymerase
bactericial
Broad G +(mycobacterium), narrow Gram - (brucella)
can interact with other meds like warfarin or steroids
mechanism of action for novobiocin
Inhibits DNA Gyrase (Topoisomerase-II) (Potency»_space; Fluoroquinolones)
narrow spectrum Gram +
when to use metronidazole
anaerobic infections: clostridium
protozoal infections: giardia
rapid bactericial
prodrug that is activated in anaerobes and prevents DNA synthesis
how does metronidazole work
prodrug is changed by ferredoxin in anaerobes to generate active metabolit
Binds to DNA and causes its fragmentation - prevents DNA synthesis
anaerobic infections: clostridium
protozoal infections: giardia
— is only effective against obligate anaerobic bacteria
metronidazole
prodrug that is turned into metabolite that prevents DNA synthesis by binding and causing fragmentation of DNA
The — bind to nicked DNA and inhibit DNA Gyrase (Topoisomerase II) that is only present in bacteria.
Fluoroqinolones
— block the activity of RNA polymerase and prevent RNA synthesis.
Rifamycins
— binds to and inactivates Topoisomerase-II by preventing ATP binding
Novobiocin
— is a prodrug that generates free radicals in anaerobic bacteria. These radicals fragment the bacterial DNA
Metronidazole
what are some drugs that inhibit protein synthesis by disrupting bacterial ribosomal function .
Aminoglycosides, Tetracyclines, Puromycin, Macrolides, Lincosamides, Chloramphenicol
