The objective of this experiment is to test and apply the knowledge as well as lab techniques acquired throughout the semester from my Microbiology lab to identify an unknown bacterium given in class. A case study was assigned with the following information:
James visits the hospital after a fun weekend of celebrating his college graduation. For the last 24 hours, he has been experiencing a range of symptoms including nausea, vomiting, diarrhea, headaches, and occasional muscle cramping. He cannot resolve which recent food item caused this onset of symptoms. However, he mentions to having hosted a potluck style party during that weekend.
A sample was taken from James and cultured in a broth media where further testing will be done to determine…show more content… If the pH indicator in the medium changes from a red color broth to a yellow color broth, it suggests maltose fermentation. However, if the red broth remains as it is, then we can consider no fermentation of maltose. After incubation, I speculated the broth and saw that it had turned to a yellow color broth, which led me to believe it the fermentation of maltose was taken place. I progressed through the next step of the identification process by obtaining a Nitrate broth and inoculating the bacteria to decide if the organism is able to perform nitrate respiration. Through this step, I will be able to differentiate if my unknown can partially reduce nitrate to nitrite or completely reduce nitrate. After incubating my bacteria in the nitrate broth for 48 hours, I took it out and added nitrate reagent A, which is sulfanilic acid, and nitrate reagent B, which is naphthylamine, to test for the reduction of nitrate to nitrite. Gradually, a red color began to develop which indicated a partial reduction of nitrate to nitrite had occurred and the presence of nitrate reductase was detected. Given my test result of the bacteria was Nitrate-positive and according to the chart I was given in the Microbiology lab guide of the identification process, I was currently down to three possibilities of the agent that was causing James’s illness, which are Staphylococcus Aureus, Staphylococcus Gallinarium, and Staphylococcus Epidermis. To simplify my choices down a little more, I chose to another test by inoculating the bacteria onto a Mannitol Salt Agar plate. If I get a positive result on my Mannitol Salt Agar test, I would be able to reduce my number of bacteria to possibly Staphylococcus Aureus or Staphylococcus Gallinarium. However, if it was negative, there could be a great chance my bacteria could also be Staphylococcus
