Ex. 12: Chemical Antimicrobial Agents: Antibiotics
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Transcript of Ex. 12: Chemical Antimicrobial Agents: Antibiotics
Ex. 12: Chemical Antimicrobial Agents: Antibiotics
Objectives ??
Fleming and the Discovery of Penicillin
1928 mold grows on Staphylococcus aureus plate
Mold is named Penicillium notatum
Florey and Chain isolated Penicillin 10 years later – received Nobel prize
Vocabulary Antibiotics vs. chemotherapeutic agents bacteriostatic vs. bactericidal Commonly used antibiotics: Penicillin,
Ampicillin, Tetracycline, Vancomycin, Ciprofloxacin
Agar Disk Diffusion Test or Kirby-Bauer Antimicrobial Susceptibility Test
Mueller-Hinton (MH) agar
Materials needed per student: One Petri plate containing
Mueller-Hinton (MH) agar One of the four bacterial
species assigned per table Sterile cotton swab
Materials needed per table: One 0.5 McFarland standard (contains
~ 1.5 x 108 CFU/ml) Four sterile saline tubes Four 1 ml sterile pipettes Five single disk dispensers plus five
cartridges of antibiotic disks (P, AM, T, VA, CIP).
One each of the following pure cultures:o E.coli ATCC: 25922o S. aureus ATCC 25923o P. aeruginosa, o S. marcescens
Materials needed per team of two: Laminated white card with
black lines Bunsen burner, inoculating
loop
Each student tests all the antibiotics for one bacterial species
Day 1
Mark the bottom of your plate with a line. This will be your #1 position.
How to streak for confluent growth
Rotate 60º clockwise
Rotate 30º clockwise
Review this 5 mins (in-house) movie clip on how to test for antibiotic susceptibility with the Kirby Bauer method.
Day 2Examine each plate and look for “zones of inhibition”. Measure of Zone of inhibition (in mm) and record the value in the table in the lab report section