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 10 8 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: o S. aureus ATCC o 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.(in-house) movie clip

Day 2 Examine 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