antibiotics Flashcards
what is an antibiotic
anti-bacterial
how do antibiotics basically work
molecules that work by binding a target site on a bacteria
how will the binding site vary
vary due to the antibiotic class
how do antibiotic classes differ
due to the location of binding
three classes of antibiotics
cell wall synthesis
nucleic acid synthesis
protein synthesis
main group with cell wall synthesis
beta lactans
examples of beta lactans
penicillins
cephalosporins
carbapenems
examples of some penicillins
peniccilin v
penicillin g
flucoxallinin
examples of glycopeptides
vancomycin
teicoplan
beta lactam antibiotics mechanism?
-disrupt peptidoglycan production
-binding covalently and irreversibly to the Penicillin Binding Proteins
-cell wall is disrupted and lysis occurs
-results in a hypo-osmotic or iso-osmotic environment
why is gram negative bacteria hard to use with beta lactams
it has an additional lipopolysaccharide layer which makes penetration difficult
most used examples of nucleid acid synthesis medicines
metronidazole
ciprofloxacin
nucleic acid synthesis antibiotic mechanism?
prevent production of folic acid so you cant make pyrine bases ro make dna
affect enzymes that are involved in dna replcate such as dna gryase, rna polymerase
PROTEUN SYN
aminoglycosides- gentamincin
tetracylince
Folate synthesis mechanism ?
NO FOLATE- NO REPLCIATION OF CELLS
examples of folate synthesis antibiotics
trimethoprim
co- trimoxazole
consequences of bacteria
- destroy phagocytes or cells in which bacteria replicate
- inflammation - necrotic cells
-diarrhoea - exotoxin- protein production
two main ways antibiotics work
- kill the bacteria
- prevent growth of bacteria
how would an antibiotic work effectively
should remain at binding site, for a sufficient period of time in order for the metabolic processes to be sufficiently inhibited.
two major determinants of bacterial efficacy?
concentration
time
pharmcokinetics relation to antibiotics ?
its release from dosage
its absorption
its distribution
rate of elimination
how do bacteria resist antibiotics
change antibiotic target- by changing binding site
destroy antibiotic -
prevent antibiotic access- modify the bacterial membrane porin channel, size and selectivity
remove antibiotic from bacteria-proteins in bacterial membranes act as an export or efflux pump
what two ways do bacteria become resistant
intrinsic
acquired
what happens in intrinsic resistance
naturally resistant
example of intrinsic resistance
Aerobic bacteria are unable to reduce metronidazole to its active form
Vancomycin cannot penetrate outer membrane of gram negative bacteria
what happens in acquired resistance
spontaneous gene mutation
horizontal gene transfer
what can mrsa become resistant to
flucloxacillin
why would you never give trimethoprim to a pregnant woman
it prevents folate production which is key to prevent spina bifida
how can horizontal gene transfer cause antibiotic ressitance
conjugation
transformation
transduction
WHAT can streptococcus be treated with
penicillin’s
What factors to consider when deciding if an antibiotic is safe to prescribe?
Intolerance, allergy and anaphylaxis
Side effects
Age
Renal and Liver function
Pregnancy and breast feeding
Drug interactions
Risk of Clostridium difficile
what is amoxicillin- clavulanate
amoxicillin and clavulonic acid
what can cause cellulitis of the foot
s.aureus
group a c g strep
what woudl you give to someone w s,aureus and beta haemolysis
flucloxacillin
who would you give penicillin to
pharyngitis
penicillin
what does MRSA stand for
Methicillin*-resistant Staphylococcus aureus
examples of macrolides and use
clarithromycin and erythromycin
for s.aureus
what does clindamycin do
turns off nasty toxins made by gram positive bugs
main difference between gram neg and pos
neg has a thin cell wall
pos has a thick lipolysaccaride layer
main difference between gram neg and pos
neg has a thin cell wall
pos has a thick liposaccharide layer
what will gram neg cause
intra abdo infections
diarrohoea
appendicitis
what is gentamicin used for
UTI’s
