Antibacterials 2 Flashcards
what two antibacterials target the cell envelope
beta-lactams and glycopeptides
what do beta-lactams consist of
beta lactam ring
what do beta-lactams compete with
d-ala d-alanine
what does the serine in b-lactams cause
breaking down of d-ala d-ala
what does b-lactam bind to and what does it cause
to the active site so transpeptidation cannot occur
After b-lactam is bound to the active site so transpeptidation cannot occur what does this result in
cross-links cannot form resulting in a weak cell wall and lysing of the cell
What are the three types of beta-lactam
penicilin (penicillin G), cephlasporins and carbapenems
What are carbapenems used for
last port of call for gram negative that are multidrug resistant
what is penicillin G used to treat
pneumonia, syphillis and gonorrhea
three glycopeptides
Vancomycin, Polymyxins B and E, daptomycin
what is the prime mode of action of vancomycin
transglycoylation
what does vancomycin bind to
d-ala d-ala
is vancomycin active against gram negative
no
why might vancomycin be used
if the patient cannot have b-lactam because of resistance or hypersensitivity
what is vancomycin used to treat
serious MRSA and other gram positives
adverse side effects of vancomycin (5)
'Red man' Histamine release Ototoxic Neutropenia Thrombocytopenia
are polymyxins active for gram positives
no
what do polymyxins interact with
liposaccharide leaflet of -VE, penetrating outer membrane
what are polymyxins used to treat
cystic fibrosis, decontamination of gut and burns infections
toxicity of polymyxins
potential neurotoxicity and nephro due to accumulation on kidneys
how does daptomycin work
by interaction with membrane via acyl chain integration , causing integration, aggregation and membrane depolarisation causing leakagr and cell death
are daptomycins used for gram negative
no
what are daptomycins used to treat
soft tissue infections
what two drugs target nucleic acids and nucleic acid biosynthesis
Sulfa drugs and trimethoprim
how do drugs that target nucleic acids and their biosynthesis work
inhibiting dihydropteroate synthase ( DHPS)
how do sulfa drugs work
they are structural analogues of the substrates for DHPS
what are the substrates for DHPS
p-aminobenzoic acid
what happens when sulfa binds to DHPS
forms a dead end complex and therefore no tetrahydrofolate
what is trimethoprim formed of
2 pyridimes joined together
how does trimethoprim work
inhibiting dihydrofolic reductase catalysing the reduction of dihydrofolic acid to tetrahydrofolic acid
what are both sulfa and trimethoprim used to treat
short term respiratory, urinary and digestive tract infections
what are sulfa and trimethoprim used to treat in HIV patients
pneumonia
what two drugs are involved in targeting the synthesis of DNA-pre-existing DNA
Quinolones and fluoroquinolones
what do all quinolones and fluoroquinolones drugs end in
-floaxacin
how do quinolones and fluoroqunolones work (2 things)
- they interfere with enzymes responsible for bacterial topology
- they catalyse ATP dependant DNA double strand breakages
what two enzymes do quinolones and fluoroquinolones target
DNA gyrase and DNA topoisomerase IV
how do nitroheterocyclic drugs work
targeting obligate anaerobes to cause DNA damage
two examples of nitroheterocyclic drugs
Metronidazole and Tinidazole
are nitroheterocyclic bacteriostatic or cidal
cidal
what drug works by targeting RNA synthetase
Rifamycin
how does Rifamycin stop rNA synthetase
blocks RNA exit channel, RNA knocks into rifamycin and spontaneously dissociates
is rifamycin bacteriostatic or cidal
cidal
what is rifamycin used to treat
TB, leprosy, penicillin resistant s.pneumoniae
