AntiR Flashcards
Why is resistance a global concern?
→Increases mortality
→challenges control of infectious diseases
→threatens a return to the pre-antibiotic era
→increases the costs of health care
→jeopardizes health-care gains to society
What are beta lactamase?
→enzymes produced by bacteria that break open the beta-lactam ring, inactivating the beta-lactam antibiotic
What is methicillin?
→lactamase resistant penicillin
What is MRSA?
→methicillin-resistant Staphylococcus aureus
What 2 factors lead to vancomycin resistant MRSA?
→Co-infection
→genetic exchange
Examples of syperbugzillas?
→Enterococci - G+ve
→Acinetobacters- G-ve
→MRSA- G+ve
What are the mechanisms of antibiotic resistance?
→Drug inactivation →Altered or new target →Metabolic by-pass →Efflux pump- pump drug outside of cell →Intrinsic impermeability →Overproduction of target- increased folic acid
What features of protein synthesis can be a source of resistance?
→Ribosome →Porin mutations so antibiotic can’t get through →PBPs – peptidoglycan synthesis →DNA gyrase →RNA polymerase →Mcr1 & colistin
Why can efflux pumps increase resistance?
→by acquisition of pumps
→mutations or over expression
What can be overproduced as a mechanism of antibiotic resistance?
→precursor trimethoprim
What are the different paths to resistance?
→Directed at antibiotic itself
→New or Altered target
→Altered transport- excess pump
→Metabolic by-pass- metabolic change D-ala-D-lac and vancomycin
What are the three types mechanisms of resistance?
→Natural resistance
→Genetic Mechanisms - acquired
→Non-Genetic Mechanisms (growth phases) tolerance
What structure in the cell wall of bacteria results in multiple resistance?
→Porins
What are the two genetic mechanisms of resistance?
→Chromosome-mediated
→Plasmid-mediated gene exchange
Describe chromosome-mediated resistance
→spontaneous mutation:
→in the target molecule
→in the drug uptake system
→Mutants are SELECTED; they are NOT induced