Year 2 recap Flashcards
define an antibiotic?
a chemical agend used to inhibit or kill other organisms
bacteriostatic and bactericidal
ability to inhibit visible bacterial growth
to kill bacteria
synergism
antagonism
indifference
work together to increase activity
one agent diminishes the other
no impact on one another
give a clinical relevant example of synergism?
beta lactams
aminoglycosides
used to treat step. endocarditis
mechanism of antibiotic action?
inhibit key processes e.g. structure of proteins, molecules, enzyme activity
- selective toxicity- only bind to target cells and host cells
a key example of selective toxicity ?
cell wall component - peptiglycans
not present in human cells
give example of 4 cell well inhibitors?
Beta lactams
Fosfomycin
Glycopeptides
Cyclosenne
cBFG
discuss beta lactams
first antibiotic in practice - benzylpencillin
possesses a beta lactam ring - C C C N
works to interfere with enzyme function for cross linking ( transpeptidase )
both broad and narrow spectrum
give example of narrow and broad spectrums and their subnames
NARROW
- pencillin - amoxicillin, flucoaxacillin
BROAD
- cephalosporin - Cefuroxime, ceftazidime
- Carbapenem - miropenems, imipenems
- monobactams - azotreonam
key feature of azotrenams
gram neg only
name a glycopeptide
vancomycin
what is it often used to treat
MRSA
what does it bind onto?
terminal D alanyl D analogue and impairs activity of transpeptidase
what does it act on? gram neg or pos?
gram pos only
name four categories of protein synthesis inhibitors and their mechanisms?
Aminoglyocoside inhibit 30s subunit
Macrolide - inhibit 50s subunit and elongation
Tetracycline - inhibit 30s - prevent translation of RNA
Ozo binds to 50s subunit and prevent initation complex formation
name examples of each
A-gentamicin
M - clindamycin, erythromycin, clarithromycin,
T -doxycycline
O- linezolid
name other protein synthesis inhibitors?
mupirocin
fusidic acid
name a RNA synthesis inhibitor?
rifampicin
inhibit mRNA synthesis by inhibiting RNA polymerase
DNA synthesis inhibitors? what do they inhibit
what are their uses
trimethoprim - dihydrofolate reductase - treating utis
sulfonamide dihydropheroate synthesis - toxic so rarely used
name of them when combined?
co-trimoxazole
Moa of dna synthesis inhibitors?
inhibit folate synthesis
example of quinolones and fluroquinolones?
mechanism of action?
ciprofloxacin, levofloxacin
inhibit 1 or more enzyme
name two plasma membrane agents
which is gram N and P
clostrin (gram N)
daptomycin (gram P)
side effects specific to aminoglycosides?
ototoxicity - irreversible
reversible renal impairment
SE of linezolid?
bone marrow suppression
SE of beta lactams?
intolerance- diarrhoea, headache, nausea
minor allergy - non specific rash
severe- anaphylaxis, steven Johnson syndrome, uticaria
safe antibiotics for penicillin allergy?
monobactams - azetreonam, cephalosporin, carbapenems
4 causing c difficile - which 2 are high risk?
co-amoxiclav
cephalosporin - HR
-clindamycin- HR
ciprofloxacin
three reasons to combine therapy?
increase efficacy
reduce resistance
provide adequate broad spectrum
what can vancomycin be used to treat?
MRSA
what can flucloxacillin be used to treat?
s. aureus
what can benzypencillin be used to treat?
s. pyogenes
what can metronidazole be used to treat?
anaerobes
what can cephalosporins be used to treat?
gram negative
two key differences between human cell and fungi?
has a cell wall - bet 1 ,3 glycan
cell membrane with ergosterol
synthesis of ergosterol?
squalene SQUALENE EPOXIDASE lanosterol LANSTEROL 14alpha demethylase to egosterol
what synthesis beta 1,3, glucans?
1,3 glucan synthase
five classes of anti-fungals
Polynes
Aallylamines
Azole
Echinocandins
Other
PAAE
what is the mechanism of polyenes?
pushes apart egosterol forming large pore in the membrane
these allows K+ to leak out and results in cell death
give two examples
nystatin
amphotericin B
key features of nystatin?
toxic for systemic use so given for superficial infections e.g. skin, mouth vagina
key feature of amphotericin B?
spectrum of activity
but has side effects - nephrotoxicity and can cause allergic reaction
lipid associated amphotericin B? whats it used for?
amphotericin B with lipids
this reduces delivery to kidney cells and reduces nephrotoxicity
mechanism of allylamine?
inhibit ergosterol synthesis by inhibiting squalene epoxidase
name an example of an allylammine and its use?
terbinefine - atheletes foot
pro and con of this medication?
hepatotoxic
broad spectrum
what is it also used to treat?
orally for scalp ring worm and dermphocyte infection
give two examples of azoles and outline the difference between them both? which is rarely used
imidazole - 2 nitrogen atoms - TOXIC rarely used
triazole - three Nitrogen atoms - used for systemic use
MOA of azoles?
inhibits lansterol 14alpha dimethylase
example of both classes of AZOLES?
imidazole - C M K
clotrimadazole, miconazole, ketoconazole
Triazole - F I T V
fluconazole, intraconazole, voricondazole
SE of azoles?
hepatotoxicity
inhibit action of P450 enzyme
mechanism of echinocandins?
exaples
inhibit 1,3 glucan synthesis therefore does not construct cell wall
micofungin, caspofungin
USES OF FLUROCYTOSINE?
MOA
SE
developed as an anti cancer drug but found to have antifungal properities
inhibits DNA and protein synthesis
used to treat cryptococcal meningitis
SE - bone marrow suppression
