antimicrobial resistance Flashcards
Where is ampC info located?
Chromosomally
ampC is resistance to:
beta lactamases: penicillin and cephalosporin (cannot be inhibited by beta lactamase inhibitors)
Which 2 organisms can have ampC?
EnterobacterPseudomonas
List 3 enterobacteriaceae
EnterobacterE coliKlebsiella
2 drugs that can induce amp C
cefazolinampicilin
ESBL is located in?
plasmid
amp expression can be _____ or _____
inducible or constitutive
ESBL is in which 2 bugs?
E. Coli and Klebsiella
b-lactamase inhibitor’s effect onESBL and ampC
Can help with ESBL but cannot help with amp C
Who can acquire erm and msr?
Staph AureusStrep Pneumo
erm is inducible by?
only by macrolides
erm affects which two drugs
macrolides (Erythromycin induced) and clindamycin
Why are ERM and ampC important
single mutation –> change to consitutive on.Can occur DURING therapy
How does erm work?
dimethylation of 23S rRNA.Macrolides cannot bind to 23s rRNA (part of 50S)
How does msr gene work?
drug efflux
what does erm-D-test tell you?
If bug has erm (inducible) or efflux resistence.
What can you treat with if bug has msr (efflux resistance) (clindamycin/macrolides)
Clindamycin - yesMacrolides - no
What can you treat with if bug has erm (inducible)?(clindamycin/macrolides)
Do not use clindamycinDo not use Macrolides
Who has narrow spectrum b-lactamase?
S. Aureus (MSSA)E.coli TEM-1Klebs Pneumo SHV1
narrow spectrum b-lactamse resists which drugs?
penicillinAmpicillin
ESBL (plasmids) resists which drugs?
Penicillins + cephalosporins
_____ and ______ both resists penicillin and cephalosporin?
ESBL and ampC
MRSA resistance (gene: mecA) due to?
PBP –> PBP2a (low affinity)
VRE has two genes ____ and ____ and located in ______
van A, vanB, plasmid
How does vancomysin work?
Bind to precursor for cell wall
How does VRE have resistance?
Precursor is changed to D-ala-D-lac (from D-ala-D-ala)
How does N. Gonorrhoeae have resistance?
altered PBP
3 main ways antibiotic resistance
- inactivate/modify drug2. Alter drug target3. reduce ability of drug to get to target
E. Coli TEM-1 vs E. Coli
gained penicillimase from plasmid
Ecoli’s TEM1 vs Klebsiella SHV1 location difference
Ecoli TEM1 - plasmidKlebsilla SHV1 - chromosomal
Two plasmid that causes resistance of penicillin, cephalosporin, AND carbapenem?
KPCNDM1
Aminoglycosides resistance occurs how?
Inactivating/modifying drug:N – acetylation, O-nucleotidylation, O-phosphorylation
Two ways altered PBP?
mecA (MRSA) - PBP2aMosaic PBP (strp pneumoniae/N. gonorrhoeae)
VISA (vancomycin - intermediate - susceptibility S. aureus) have two major diff from sensitive strains
- thicker layer of peptidoglycan2. Less cross linking (absorbs vanco)
_____ of DNA gyrase and ____ of topo IV have quinolone resistance determining region (QRDR)
GyrA & ParC
QRDR (quinolone resistance determining region) effect
enzyme less sensitive to inhibition by quinolones –> reduce drug/target affinity
