Log of Observations-Phase One

01/05/01(Updated by Emily)-Today we realized that we made a horrible mistake with our experiments....Not only did we attempt to place the antibiotic disks on an already established colony of bacteria, but we also neglected to discover what type of solutions the antibiotics needed to be in! Jenn spoke with her aunt, who is a nurse. She suggested that we call the company, to find out the specifications of rehydrating the powdered antibiotics. We did this, and found out the Tetracycline needed to be dissolved in 1 molar HCl and Cephlexin needed to be dissolved in 1 molar ammonium hydroxide. We discovered that we would not be able to rehydrate the Penicillin G due to the fact that it needed to be hydrated in chloroform, which is not a substance to be used in school. With this information in hand, we set out to fix out mistakes....

01/08/01(Updated by Jenn)-Today we attempted to fix our previous mistakes. We made our plates today and did not incubate them for 24 hours. We made our disks for Oxacillin, Vancomycin, and Tetracycline. The concentration we used was 100mg of antibiotic per 2mL of liquid. We are more confident today and hopeful that we will see results tomorrow...

01/09/01(Updated by Jenn)-We observed our plates from yesterday. We were very pleased with the results. Our first three antibiotics worked quite well against both bacteria. For the S. aureus, Vancomycin worked the best; Tetracycline was second, and Oxacillin had the smallest zone, yet it was still not too bad. The antibiotics also worked on S. epidermidis quite well. Oxacillin had the largest zone, Tetracycline, the second, and Vancomycin had the smallest. We also made our disks and plates for Cephalexin using the same concentration as we did for the others. They will be observed tomorrow.

01/11/01(Updated by Jenn)-Cephalexin also worked. For S. aureus, Tetracycline and Cephalexin had equal zones of inhibition. We could not see any change to S. epidermidis.