Chloe Evetts (8990-4674)
Cameron Jacobs (7908-1325)
Being able to control and stop microbial growth is of utmost importance to the health and
wellbeing of human beings and animals alike. Unknown disease causing microbes could wreak
havoc if they are allowed to replicate interrupted with no possibility of combating these invaders.
The purpose of this lab is to learn the different methods of antimicrobial control, including
biological, physical, mechanical, and chemical methods and how to use these to control foreign
invaders. The Kirby-Bauer Antibiotic Disk Diffusion will be used to determine the efficacy of
the antibiotics Penicillin, Vancomycin, Oxacillin, Gentamicin, Tetracycline, Chloramphenicol
and various reagents including mouthwash, disinfectants, and cleaning reagents against
Escherichia coli and Staphylococcus aureus.
We believe that by correctly using proper aseptic techniques, by properly inoculating
Escherichia coli and Staphylococcus aureus onto agar plates, and by using the Kirby-Bauer Antibiotic Disk Diffusion method, we will be able to determine the efficacy of each agent against
the two species. Efficacy will be able to be determined by analyzing the zone of clearing, a clear
area around the disk that equates to no microbial growth. The larger the zone of clearing, the
smaller the minimum inhibitory concentration.
1 Lab 1a:
a Label the bottom of each Mueller-Hinton agar plate with your initials, date,
medium type and test microorganism.
b Using aseptic technique, inoculate each plate with their respective test organisms
i Immerse the swab into the culture tube and squeeze excess culture on the
inner wall of the tube.
ii Using the swab, streak the entire surface of the plate three times, (rotating
the plate 60° each time).
iii Finally, run the swab around the outer edge of the plate.
iv Allow each plate to dry for 5 to 10 minutes at room temperature.
c Apply the antibiotics individually to the surface with forceps dipped in alcohol
and flamed. Make sure that contact is made with the surface. DO NOT PRESS
THEANTIBIOTIC INTO THEAGAR. DO NOT REMOVE THEANTIBIOTIC
ONCE IT HAS BEEN PLACED ON THEAGAR.
d Incubate the Mueller-Hinton agar plates for 24 to 48 hours in an inv