PRE LAB 4.1 AST Flashcards
antibiotic sensitivity testing determines what
the effectiveness of the antibiotic against a specific bacteria or microorganism
AST identify whether the bacteria is ____ or _____ to a particular antibiotics
sensitive or resistant
The AST is vital in ________________ that is caused by ______ or of antibiotics
combating antibiotic resistance
misuse or overuse
What are the four purposes and significance of AST?
1) Guides clinicians in selecting the most effective antibiotic for individual patient, especially when the causative bacterium is identified.
2) Controls inappropriate usage of antibiotics in clinical practices
3) Provides epidemiological data on resistant bacteria for public health
4) Reveals changing trend on local bacteria isolates based on the presence of resistance genes.
What are the two key methods in AST?
1) Diffusion method - uses solid agar
2) Dilution method - uses liquid broth and antibiotics in varying conc.
Two subtypes of diffusion method
1) Disc diffusion method (Kirby Bauer)
2) Agar well method
describe kirby bauer test
- uses antibiotic discs or soaking filter paper (whatman No.2) with the test substance before placin on the agar
Describe agar well method
- uses wells in agar to test the effectiveness of crude extracts or plant oils
Dilution method focuses on the determination of
Minimum inhibitory concentration or the lowest concentration of antibiotic to inhibit bacterial growth.
This test combines both principles of diffusion and dilution method using a plastic wrap containing a gradient of antibiotic concentration placed on a solid agar
Epsilometer test
Historically, mircoorganisms were highly sensitive to antibiotics but resistance increased due to (1) and (2)
improper prescription use
drug effectiveness variation
