Patient with diarrhea and ahritis showing fever, abdominal cramps, nausea, and vomiting with finger swelling. Which of the following organism is responsible?
**Core Concept**
Reactive arthritis is a type of spondyloarthritis that occurs in response to an infection elsewhere in the body, typically in the gastrointestinal tract or the urogenital tract. It is characterized by symptoms such as joint pain, fever, and systemic symptoms like diarrhea and abdominal cramps.
**Why the Correct Answer is Right**
The correct answer is an organism that commonly causes bacterial gastroenteritis, which can trigger reactive arthritis in susceptible individuals. The pathophysiology involves an abnormal immune response to the infection, leading to inflammation in the joints and other tissues. The organism in question is a gram-negative bacterium that produces enterotoxins and invades the intestinal epithelial cells, causing inflammation and tissue damage.
**Why Each Wrong Option is Incorrect**
**Option A:** This organism is a common cause of urinary tract infections and sepsis, but it is not typically associated with reactive arthritis. It is a gram-negative bacterium that can cause a range of clinical syndromes, but its pathophysiology is distinct from that of the correct answer.
**Option B:** This organism is a gram-positive bacterium that causes skin infections and is not typically associated with reactive arthritis. It produces toxins that cause tissue damage and inflammation, but its virulence factors are different from those of the correct answer.
**Option D:** This organism is a protozoan parasite that causes intestinal infections, but it is not typically associated with reactive arthritis. It invades the intestinal epithelial cells and causes inflammation, but its pathophysiology is distinct from that of the correct answer.
**Clinical Pearl / High-Yield Fact**
Reactive arthritis is a type of spondyloarthritis that occurs in response to an infection elsewhere in the body, and it is often associated with the presence of HLA-B27 antigen. Patients with reactive arthritis may also develop uveitis, conjunctivitis, or other extra-articular manifestations.
**Correct Answer: C. Salmonella.