A 53 year old woman with diarrhea and lower abdominal pain of 3 days duration comes to her physician after failing to relieve her symptoms with various home remedies. She denies any recent travel and states that there is blood and pus in her stool. Fecal cultures yield several flagellated, curved, oxidase positive, gram negative rods. The organism isolated is most likely ?
**Core Concept**
The patient's symptoms and laboratory findings suggest an infectious cause of diarrhea, likely due to a bacterial pathogen. The presence of blood and pus in the stool, along with the patient's failure to respond to home remedies, indicates a more severe infection. The flagellated, curved, oxidase-positive, gram-negative rods isolated from the fecal cultures are a key clue to identifying the causative organism.
**Why the Correct Answer is Right**
The organism in question is likely *Campylobacter jejuni*, a common cause of bacterial gastroenteritis. *C. jejuni* is a gram-negative, curved rod with a distinctive bipolar staining pattern. It is oxidase-positive and flagellated, which matches the laboratory findings. The organism is known to cause diarrhea, abdominal pain, and, in some cases, bloody stools. The pathogenesis of *C. jejuni* involves invasion of the intestinal epithelial cells, leading to inflammation and tissue damage.
**Why Each Wrong Option is Incorrect**
*Option A:* This option is incorrect because *Shigella* species are non-motile, non-flagellated, and do not match the laboratory findings. While *Shigella* can cause dysentery with bloody stools, it does not match the description of the organism isolated.
*Option B:* This option is incorrect because *Salmonella* species are typically larger and more rod-shaped than *C. jejuni*. While *Salmonella* can cause gastroenteritis, it does not match the laboratory findings.
*Option C:* This option is incorrect because *Escherichia coli* (E. coli) is a gram-negative rod, but it does not typically exhibit the curved, flagellated morphology of *C. jejuni*. E. coli can cause a range of gastrointestinal infections, but it does not match the description of the organism isolated.
*Option D:* This option is incorrect because *Vibrio cholerae* is a gram-negative rod, but it is typically straight and does not exhibit the curved morphology of *C. jejuni*. Vibrio cholerae causes a distinct type of gastroenteritis characterized by profuse watery diarrhea, but it does not match the description of the organism isolated.
**Clinical Pearl / High-Yield Fact**
*Campylobacter jejuni* is a leading cause of bacterial gastroenteritis worldwide, and its symptoms can range from mild to severe. The organism is often transmitted through undercooked poultry or contaminated water, and it can also be transmitted through direct contact with infected animals. A key point to remember is that *C. jejuni* can cause Guillain-Barré Syndrome, a rare but serious autoimmune disorder that can occur as a complication of the infection.
**Correct Answer:** C. *Campylobacter jejuni*.