Question

Case 3

A 48-year-old man presents to the emergency department with 2 days of crampy abdominal pain, nausea, vomiting, diarrhea, and fever. He has not had any blood in his stool. He denies contact with anyone with similar symptoms recently. He has not eaten any raw or unprocessed foods recently. The only food that he did not prepare himself in the past week was a breakfast of eggs “sunny side up” and bacon that he had at a diner the day before his symptoms started. On examination, he is tired appearing; his temperature is 37.7°C. The physician interprets a positive “tilt test,” indicating significant volume depletion. His abdominal examination is notable for diffuse tenderness.  

A MacConkey agar plate culture results in the biochemical reactions as follows:

TSI K/A with H₂S, citrate positive, and urea negative. The serological test were positive for this pathogen.  

1. On the basis of the biochemical reactions, which organism do you think this is?

1. Salmonella sp.
2. Campylobacter jejuni
3. Shigella sp.
4. Escherichia coli

2. What are the most common sources of human infections with this organism?

1. Contaminated foods such as meat, poultry, eggs, fruits, and vegetables.
2. Contaminated water
3. Pasteurized dairy products
4. Unpasteurized dairy products

Answer 1

Q.1. Option A is correct, As in this case the TSI K/A with H₂S, citrate positive this is the case of infection from the Salmonella sp.

Note although there may also be the chance of the Shigella sp. but in the H2S should be absent, but in the above case H2S is present , which is the case of presence of Salmonella sp.

Q.2. Option A is correct as the Salmonella sp. is more associated with the use of contaminated foods such as meat, poultry, eggs, fruits, and vegetables.