Antimicrobials Flashcards
beta lactam drugs include
include the penicillin and cephalosporin
beta lactam drugs all have a
beta lactumn ring
how does the b-lactam drugs worrk.
bacteria cell wall is made up peptide bridge that is synthesis by the enzyme penicillin binding proteins. beta latam drugs inhibit this enzyme, therefore the cell wall of the bacteria becomes weak and the cell dies.
in order for the b lactam drugs to work the bacteria must be
growing
penicilin binding proteins are responsible for
peptidoglycan synthesis
bacteria becomes resistant to b-lactam drugs by release which enzyme
beta lactamase
cephalosporin are
new penicillin
pencillin are made from these fungi
penicillium chrysogenium
penicillin V is more stable then penicillin G because
it is more stable in acid
penicillin G
natural pencillin, narrow spectum
pencillin G and V are good in treating
gram positive bacteria
oxacillin or dicloxicillin
narrow range, good absorption, resistant to penicillase.
disadvantage of oxacillin, dicloxacillin
expensive
methicillin or nafcillicin
not susceptible to penicillase,
disadvantage of methicillin or nafcillin
allergies, poor absorption
would you choose methicillin over oxacillin
no, methicillin has poor absorption compare to oxacillin
is ampillicin and amoxicillin naroow or broad range?
broad range
ampillicin
hydrolysis by pencillinase and can cause allergies. they can also work on negative bacteria. and have a fair absorption rate.
examples of extended spectrum penicillins
ticarcillin, piperacillin
ticarcillum and pipercillin are
good for pseudomas spp but less on the gram positive organisms
Augmentin is an example of a
pencillin with a beta lactamase inhibitor.
augmentin is a combination of
amoxicillin and clavulanic acid
cephalosporins are derived from
acremonium cephalosprium.
what drug canbe given to patients who are allergic to penicillin
aztreonam
carbapenems are bata lactams that are resistant to
b-lactamse, treat both gm negative and gram positive bacteria
two types of ccarbapenems
imipenem and meropenem
imipenem
is a member of the carbapenems and is destroy by kidney enzymes and most be administered with a combination that inhibits the enzyme.
monobactam are used
aztreonam is an example and is used against enterobacteriaceae.
how does vancomycin work?
binds to the terminal amino acids (D- alanine and D-alanyl) of the peptide side chain of NAM molecules that are being assembled to form glycan chains. it therefore blockssynthesis of peptioglycan resulting in weakening of the cell wall.
can vancomycin be used to treat gram negative bacteria
no, it does not pass the outer membrane of gram negative bacteria.
how is vancomycin given
intravenously
resistanceto vancomycin is due to
changes in the peptide side chain of NAM THAT PREVENTS VANCOMYYCIN from binding
vancomycin is produced by
nocardia orientalis
vancomycin is bactericial or bacterostatic
bacteriostatic
what are the 4 phenotypes of vancomycin
van A, B,C,D
which vancomycin phenotypes have the highest resistance?
Van A,B,D
the fluoroquinolones work by
attacking enzymes (topoisomerase) that maintain the supercoiling of closed circular DNA within the bacterial cell.
what are the name if the enzymes that the fluoroquinolines attack
DNA gyrase and topoisomerase II and IV.[
Fluoroquinones are used to treat
gram negative and atypical bacteria. mycobacterium tuberculosis and bacillus anthracisfi88h888
resistance to FQ
altered cell wall, altered sites of DNA gyrase and topoisomerase IV and II, altered cell wall permeablity, expression of active efflux, cross resistance
examples of rifamycins
rifapentine, rifabutin
how does rifamycin work?
by binding to RNA polymerase, that initiates transcription.
rifamycins are bactericidal or bacteriostatic
bactericidal
rifamycin are used to treat
tuberculosis and Hansen’s disease (leprosy) , gram positive or gram positive
the structure of 70s ribosomes are
30s ribosomes and 50s ribosomes
what type of ribosomes are found in humans?
80s ribosomes
/the mitochronis has what type of ribsosome
70s
Aminoglycosides
are bactericidal drug that are irreversibly bound to the 30s ribosomal subunit, causing it to distort and malfunction.this blocks the the translation and cause misreading of mRNA by ribosomes that have already pass the initiation step.
aminoglycosides are used with and for
used with a b LACTAM DRUG and lung infections in cystic fibrosis caused by Pseudomas aeruginosa.
which aminoglycoside is too toxic for systemic use?
nneomycin
is aminoglycosides bactercidal or bacterostatic?
bacteriostatic
disadvantgae of tetracycline?
teeth discoloration in children
tetracyclines work how?
binds reversibly to the 30 subunit, blocking the attachment of tRNA to the ribosome and preventing the continuation of protein synthesis.
tetracyclines are used to treat?
gram pos, gram neg, atypical, anerobes
macrolides work by?
by binding reversibly to the 50s ribosome.
macrolide are bactericidal or bacteriostatic
bacteriostatic
macrolide are used to treat
atypical pneumonia and gram positive
macrolides are used as alternative when a patient is allergic to
pencillicin
which species of bacteria does the marcolide not work on?
enterobacteriacae
examples of marcolides
erythromycin, clarithromycin, azithromycin
chloramphenicol works?
by binding to 50s ribosomes, preventing peptide bonds from being formied and consequently blocking protein synthesis.
chloramphenicol is only used when and why
life threatening conditions and it causes aplastic anaemia.
lincosamides work by
binding to the 50s ribosomal subunit and prevent the continuation of protein synthesis. and inhibts gram positve and negative organisms.
lincosamides are primarily used to treat
bacteriodes flora
oxazolidinones
they bind to 50s ribosomes, and interfere with the initation of protein synthesis.
what is the first drug in the oxazolidinones
linezoid
streptogramins
quinupristin and dalfopristin are administered together in a new medication called synercid.
when are stretogramins used?
in the cases when beta lactams and vancomycin are resistat.
drugs that bind to the 50 ribsome
macrolides
chloramphenicol
lincosamide
oxazolidinones
30s ribsomes
aminoglycosides
tetracyclines
streptogramins
Sulfonamides work by
Sulfa drugs are structurally similar to. To paraaminobenzoic acid (PABA) , a substate in the pathway for folic acid biosynthesis, because of these similarities the the enzyme that normally binds to PABA binds to sulfa drugs resulting in competitive binding
Sulfadrugs inhibit
Gram neg, gram pos , protozoan
Resistance to sulfa drugs
Acquisition of a plasmid encoded enzyme that has a Lower affinity for the drug.
Trimethoprim
Inhibits the bacterial enzyme that catalyses a metabolic step following the one inhibited by sulfonamide a.
The synergistic effect of trimethoprim and sulfanomide treat
Uti
Action of polymyxin B
Seen in first aid kits, it binds to the membrane of gram negative and alters the permeablity leading to leakage of the cellular components.
Disadvantage of polymyxin b
Also industal eukaryote cells
Daptomycin
Inds to the bacterial cytoplasmic membrane resulting in death of the cell by mechanism.
Why is it so hard to treat tb?
Slow growth, chronic growth, waxy cell
Isoniazids work?
Inhibits the synthesis of mycolic acids
Ethambutol
Inhibits the enzyme that are required for synthesis of other mycobacterial cell wall components.