A 23-year-old male presented with abdominal pain and bloody diarrhea of one-week duration. The following rectal mucosa biopsy is diagnostic of infection with –
**Core Concept**
The question is testing the ability to identify a specific gastrointestinal pathogen based on clinical presentation and histopathological findings. The correct answer requires knowledge of the characteristic histopathological features of various gastrointestinal pathogens.
**Why the Correct Answer is Right**
The patient's symptoms of abdominal pain and bloody diarrhea are consistent with an invasive bacterial infection. The rectal mucosa biopsy is diagnostic of infection with *Shigella dysenteriae*. This bacterium invades the intestinal epithelial cells, causing inflammation and bleeding, which is reflected in the patient's symptoms. The histopathological findings would show evidence of crypt abscesses, inflammation, and ulceration of the intestinal mucosa.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not match the clinical presentation and histopathological findings. The patient's symptoms are not typical for *Salmonella* infection, which is often associated with a milder illness.
* **Option B:** This option is incorrect because it does not match the histopathological findings. *Campylobacter* infection is often associated with a more chronic course and histopathological findings may show a more diffuse inflammation.
**Clinical Pearl / High-Yield Fact**
When diagnosing gastrointestinal infections, it's essential to consider the patient's clinical presentation, travel history, and laboratory findings. Histopathological examination of rectal mucosa biopsy can be diagnostic in cases where the clinical presentation is suggestive of an invasive bacterial infection.
**Correct Answer:** C. *Shigella dysenteriae*.