Microbiology Lab

Mackenzie Strang Homework Quesons: 10 points 1.How did Max most likely get sick and what was the source of the pathogen? -Max had chicken for dinner the night before he got sick. Chickens feces at the farm were found to carry anbioc resistant E. coli and Salmonella most likely from the amount of anbiocs in the chicken’s food. The doctor menoned that he did not believe the chicken was cooked thoroughly. 2. What type of agar are we using to culture? Is this agar selecve, diﬀerenal, and/or complex? -The plate used to culture was SalmonellaShigella agar (SSA). This agar is selecve because it contains selecve agents that only allow the growth of certain gram-negave bacterial strains and prevent the growth of gram-posive strains. 3. What color do Salmonella appear on this agar and why? - Salmonella appear black on the SSA plate because most Salmonella strains can reduce thiosulfate and produce hydrogen sulﬁde, which reacts with the ferric acid in the medium, making it black. 4. What color do E. coli appear on SSA and why? - E. coli appear red on the SSA plate because the medium contains the pH indicator neutral red. It becomes red when the pH is below 6.8. E. coli can cause this change because it is a lactose fermenng bacterium that converts lactose to lacc acid. 5. Bunsen burners are used extensively in microbiology. Why is it important to work in close proximity to a Bunsen burner in order to minimize contaminaon? -The ﬂame and heat from the Bunsen burner keep away and kill microorganisms that are in the air, which prevent the plate from being contaminated and overrun with other organisms. 6. Why was Max’s infecon so hard to treat? -Max’s infecon was caused by an anbioc resistant strain of Salmonella , which means that any anbiocs he was treated with that would normally work on a bacterial infecon, were not having any eﬀect.

BIO | 311 | Microbiology Lab | homework | Mackenzie Strang Homework Ques

Week 7/8 Quiz (As long as you answer the queson, I don’t care if it’s bullet points or sentences) 1. How would you classify the following organism (gram result, organizaon, shape)? Posive, Cocci, Staph 2. Explain the diﬀerences between a Beta-Hemolyc organism and a Gamma-Hemolyc organism (what would you see on SBA and why). B=lyse blood, clear zone Y= do not lyse blood, red zone 3. Which media would you use to disnguish between two gram negave species? EMB 4. Which media would you use to disnguish between various Staph organisms? CAN or MSA or Catalase 5. Interpret the following results of an unknown organism (name the organism): Gram Stain: Posive Catalase: Negave Hemolysis: Alpha Optochin: Sensive Strep Pneumo

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