Infectious Disease · Gastroenteritis
The facts most likely to be tested
Campylobacter jejuni is a curved, gram-negative, S-shaped rod that grows best at 42°C (thermophilic) in a microaerophilic environment.
The most common source of transmission is the ingestion of undercooked poultry or contact with infected domestic animals.
Clinical presentation typically involves fever, abdominal pain that can mimic acute appendicitis, and bloody diarrhea.
Campylobacter jejuni is the most common antecedent infection associated with the development of Guillain-Barré syndrome due to molecular mimicry.
Stool culture on Skirrow medium (containing antibiotics to inhibit normal flora) is the diagnostic gold standard for identifying the organism.
Microscopic examination of stool reveals fecal leukocytes and erythrocytes, indicating an invasive, inflammatory diarrheal process.
First-line treatment for severe or prolonged cases is azithromycin, as resistance to fluoroquinolones is increasingly common.
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A 24-year-old male presents to the urgent care clinic with 3 days of fever, severe periumbilical abdominal pain, and frequent bloody stools. He reports eating undercooked chicken at a barbecue four days ago. On physical examination, he has tenderness in the right lower quadrant without rebound tenderness. Stool studies are positive for fecal leukocytes and occult blood.
What is the most likely pathogen responsible for this patient's clinical presentation?
Campylobacter jejuni
The patient's history of undercooked poultry consumption, bloody diarrhea, and abdominal pain mimicking appendicitis is classic for Campylobacter jejuni, which is confirmed by the presence of fecal leukocytes.
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Etiology / Epidemiology
Most common cause of bacterial gastroenteritis; associated with undercooked poultry and raw milk.
Clinical Manifestations
Presents as pseudoappendicitis with bloody diarrhea and high fever.
Diagnosis
Stool culture on Skirrow agar at 42°C is the gold standard.
Treatment
Supportive care; Azithromycin is the first-line antibiotic for severe cases.
Prognosis
Associated with Guillain-Barré syndrome; monitor for ascending paralysis.
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Epidemiology & Etiology
This gram-negative, comma-shaped rod is the leading cause of bacterial diarrhea in the US. Transmission occurs via the fecal-oral route, primarily through ingestion of contaminated poultry or unpasteurized dairy. It is highly infectious, requiring a very low inoculum size to cause disease.
Pertinent Anatomy
The organism primarily colonizes the distal ileum and colon. Invasion of the intestinal mucosa leads to the characteristic inflammatory response and tissue damage.
Pathophysiology
The bacteria produce cytolethal distending toxin which causes cell cycle arrest and mucosal damage. This leads to an inflammatory, invasive diarrhea characterized by fecal leukocytes. The immune response is often cross-reactive, triggering post-infectious sequelae.
Clinical Manifestations
Patients present with fever, abdominal pain, and bloody diarrhea. The abdominal pain can mimic acute appendicitis due to mesenteric adenitis. Red flags include severe dehydration, high-grade fever, or signs of ascending paralysis suggesting post-infectious complications.
Diagnosis
The stool culture is the definitive diagnostic test, requiring specific microaerophilic conditions and elevated temperatures (42°C) on Skirrow agar. Fecal leukocytes are typically present on microscopy. PCR testing is increasingly used for rapid identification.
Treatment
Most cases are self-limiting and require only fluid resuscitation. In severe or prolonged cases, Azithromycin is the preferred antibiotic. Fluoroquinolones are increasingly avoided due to high rates of resistance.
Prognosis
While most recover within one week, patients must be monitored for Guillain-Barré syndrome, which typically occurs 1-3 weeks post-infection. Other rare complications include reactive arthritis and erythema nodosum.
Differential Diagnosis
Salmonella: associated with reptiles and eggs
Shigella: associated with high fever and seizures in children
Yersinia enterocolitica: mimics appendicitis but often presents with longer duration
E. coli O157:H7: associated with HUS and lack of fever
Clostridioides difficile: history of recent antibiotic use