(Finals) MicroBio Lab Exam Flashcards
are natural or synthetic products that are used to kill or stop the growth of bacteria.
Antibiotics
For testing of isolated samples from patients with less serious infections such as uncomplicated urinary tract infections
Quantitative Methods
2 CLASSIFICATION OF ANTIBIOTICS
Based on Mode of Action
1. Bactericidal - kills bacteria
2. Bacteriostatic - stops the growth
Based on Spectrum of Action
1. Broad-spectrum - targets wide variety of bacterial pathogens
2. Narrow-spectrum - targets only specific subsets of bacterial pathogens
For infections in high-risk patient groups such as immunocompromised patients, and those who are critically ill with serious infections
Qualitative Methods
2 ANTIBIOTIC SENSITIVITY TESTING
- Dilution Methods
- Diffusion Methods
Quantitative
Dilution method
Qualitative
Diffusion Method
What are the sensitivty testing under dilution methods
- Tube Dilution
- Agar dilution
What are the sensitivity testing under diffusion methods
- Kirby-Bauer test (Disk-diffusion test)
- Stokes Methods
Medium containing beef infusion, peptone and starch
Mueller-Hinton Agar
Agar Used primarily for disk diffusion method
MUELLER-HINTON AGAR
Stocks of antibiotic disks can be stored at
-20C for 1 month
after removal at refrigerator store it about 1 hour to allow the temp to equiliberate
This is an area of media where bacteria are unable to grow, due to presence of a drug that impedes their growth
Zone of Inhibition
If the observed zone of inhibition is greater than or equal to the size of the standard zone
Susceptible
if the observed zone of inhibition is smaller than the standard size
Resistant
given for zones which fall between the accepted cutoffs for the other interpretations
Intermediate
Usual temp to conduct zone of inhibition
35-37C
Standardized depth of agar
4mm usually
True or False:
Kirby bauer cannot distinguish between bacteriostatic or bactericidal
True
is the lowest concentration (expressed as mg/L or μg/μL) of an antimicrobial agent that inhibits the visible in-vitro growth of microorganisms.
Minimum Inhibitory Concentration (MIC)
is the lowest concentration or dilution that kills 99.99% of the bacteria under testing
Minimum Bactericidal Concentration (MBC)
What do you introduce into test tubes #2 to 11?
MH Broth
Add 1ml of MH Broth from #2 to #11
To test tube #12 add 2mL of MH Broth
What test tubes do you pipette 1ml of Plant Extract
Tube 1 and 2
True or False:
MIC and Zone Diameter of Inhibition are directly correlated
False, they are Inversely correlated
