Rational antimicrobial therapy Flashcards
Grampositiveaerobicbacteria
Strep
Staphaureus
Gramnegativeaerobicbacteria
E coli
Helicobacter
Anaerobicbacteria
Clostridiumperfringens
Atypical bacterial species
Rickettsia Mycoplasma Chlamydia Borrelia Bartonella Mycobacterium
Bacterialresistance
some bacteria have resistant genes
use of antimicrobials creates a selective pressure
Whentouseantimicrobials?
definitivelydiagnosed/likelydiagnosis
diseaselikelytoprogresswithoutmedicaltherapy
Wouldcausecriticalillnessifitwasnotrecognisedortreated
factors to consider when choosing antimicrobial
likelybacteriainvolved
likelysusceptibility
cultureneeded/feasible?
pharmacokineticfactorsyouneedtoconsider?
potentialsideeffects+incrriskinyourpatient?
clientcomplianceissues?
costconsiderations?
Factors affecting the success of antibacterial therapy
Whatbugslivewhere? Bacterialsusceptibility Distributiontothesiteofinfection(pharmacokineticphase) Localconditions(pharmacodynamic phase) Clientcompliance
Bacterialsusceptibility
if not susceptible in vitro - resistant in vivo
if susceptible in vitro - may work in vivo
resistancemaybeovercomebyhighconcsachievedinurineortopicalapplication
MIC
MIC=Minimuminhibitoryconcentration
Lowestconcofdrugthatwillinhibitbacterialgrowth
MIC90 usualmeasureusedtodeterminetherapeuticdose - Concthatwillinhibit90%ofisolates
Inhibitionofcellwallsynthesis
penicillins
cephalosporins
bacitracin
Inhibition of cell membrane function
polymyxins
amphotericinB
imidazoles
nystatin
Inhibition of protein synthesis
chloramphenicol macrolides lincosamides tetracyclines aminoglycosides
Inhibition of nucleic acid synthesis
sulphonamides trimethoprim quinolones metronidazole rifampin
Bacteriostatic - define
Tempinhibitthegrowthoforganisms
Effectisreversibleoncethedrugisremoved
drugconc atthesiteoftheinfectionshouldstayabovetheMICthroughoutdosinginterval
Manybacteriostaticdrugscanbebactericidalifdrugexposureissufficientlyhighorprolonged
Bacteriostatic drugs
Chloramphenicol Lincosamides Macrolides Tetracyclines Non-potentiatedsulphonamides (mostly inhibit protein synthesis)
Bactericidal - define
Underidealconditionskillbacteria
preferredwhenconcernabout siteofinfectionorhostdefence
gram+veinfections - susceptibility ofbacteriaandabilityto
penetratetissuemoreimportantconsiderations
Bactericidal drugs
Penicillins Cephalosporins Aminoglycosides Fluoroquinolones Potentiatedsulphonamides(TMPS) Metronidazole