Antibiotic Resistance and Antibiotic Use Flashcards
What is MIC?
Minimal inhibitory concentration - lowest concentration of antimicrobial that will inhibit the growth of bacteria
What is MBC?
Minimal bactericidal concentration - minimum concentration that will kill the bacteria
What is Breakpoint?
The MIC that is used to designate between susceptible and resistant
How can you test for MIC?
Serial dilutions
What is the relationship between MIC and Breakpoint?
When the MIC is lower than the breakpoint, the bacteria will be susceptible to the drug
What is the problem that breakpoint shows?
Sometimes a given concentration needed cannot be accumulated in a certain tissue
What are three types of patients that are high-risk for bacterial infection complicated by resistance?
Immunocompromised, hospitalized, invasive devices
Explain the general idea of the cycle of antibiotic resistance acquisition.
When treated with a bacteria that X gives resistance to, all those containing X will survive. These may then carry Y genes making them resistant to something else. So treating then with Y won’t do anything. And it continues…
What are three mechanisms of resistance acquisition?
Sulfonation, phosphorylation, and esterification
What is the difference between acquiring a new mechanism for resistance versus getting rid of an exisiting mechanism?
Acquiring a new mechanism will not impede bacteria function. With things like penicillin-receptors, shutting them down will impede function and growth of the bacteria by interfering with it’s own processes. So bacteria prefer to acquire new mechanisms for resistance than stop existing processes.
Where to beta-lactamases act?
They act on the cell wall
Are beta-lactamases for effective on gram- or gram+? Why?
They are more effective in gram- because they are pumped into the periplasmic space where their concentration will remain high (undiluted). Thus, they can effectively target cell wall.
Where is class a carbapenemases resistance common?
Atlantic coast
What are three mechanisms for resistance?
Decreased permeability, efflux pumps, target alteration
What are examples for target alteration?
Penicillin-binding protein in MRSA
Gram+ cell walls in vancomycin
