Ex. 12: Chemical Antimicrobial Agents: Antibiotics Objectives ??

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 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