Each question in this assignment is worth 0.5 point

Reference Table

Please refer to this table to complete the identification of the unknowns in the three case studies and the multiple choice questions.

TABLE 1. Results for biochemical tests in E. coli, Vibrio, Campylobacter, and Salmonella. A plus sign (+) indicates a positive result for that organism, a negative sign (-) indicates a negative result.

Case Study 1 – Identify the unknown using biochemical tests

Case Study 1: Patient is a 17 year old male recently returned from a mission trip to Central America. Presents with abdominal cramps and diarrhea that is unresponsive to antidiarrheal drugs. Stool cultures indicate the presence of a prokaryote. A Gram stain shows pink bacillus colonies.

1. Based on this result, is the microorganism Gram positive or Gram negative? What does this result tell us about its cell wall structure?
2. What do these results mean in terms of this microorganism’s ability to ferment lactose?
3. What does this result tell us about cytochrome c oxidase in this organism?
4. What does this result tell us about the presence of urease enzyme?
5. Based on these results, determine if the following is positive or negative in the organism.
6. Based on the above results, does this microorganism have the catalase enzyme?
7. Based on all the test results above results and the provided table, what microorganism is this? Explain your reasoning in 1-2 sentences.

Case Study 2

Case Study 2: Patient is a 60 year old male recently returned from biking/camping expedition around Lake Michigan. Patient reports eating primarily at fast food restaurants during this week-long excursion. Presents with fever, nausea, abdominal cramps and diarrhea. Stool cultures indicate the presence of a prokaryote. A Gram stain shows pink helical-shaped colonies.

8. Based on this result, is the microorganism Gram positive or Gram negative?
9. What do these results mean in terms of this microorganism’s ability to ferment lactose?
10. What does this result mean about the presence of cytochrome c oxidase?
11. What does this result mean about the presence of urease?
12. Based on these results, determine if the following is positive or negative in the organism.
13. Based on the above results, does this microorganism have the catalase enzyme?
14. Based on the above results, what microorganism is this? Explain your reasoning in 1-2 sentences.

Case Study 3

Case Study 3 -- Patient is a 53 year old female. Presents with fever, nausea, abdominal cramps and watery, slightly cloudy appearance to diarrhea with no blood or foul odor. Cultures indicate the presence of a curved shaped prokaryote that is pink after Gram stain.

15. Based on this result, is the microorganism Gram positive or Gram negative?
16. What do these results mean in terms of this microorganism’s ability to ferment lactose?
17. What does this result mean about the presence of cytochrome c oxidase?
18. What does this result mean about the presence of urease?
19. Based on these results, determine if the following is positive or negative in the organism.
20. Based on the above results, does this microorganism have the catalase enzyme?
21. Based on the above results, what microorganism is this?

Multiple Choice Questions

Choose the best answer to each of the following questions. Type your answer in the box provdied.

22. What is the organism that is gram negative, oxidase negative, urease negative, and H₂S negative?
23. Which of the following traits is characteristic of bacteria found in the GI tract?
24. How can an E. coli infection be differentiated from a Salmonella infection?