Campylobacter vs Shigella
How to tell Campylobacter and Shigella apart when a board question makes them look alike.
Step 2 CK pairs are in open beta while clinical review finishes. Spot an issue? Tell us.
Recent undercooked poultry exposure is the quickest clinical clue favoring Campylobacter.
Side by side
Inflammatory diarrhea after undercooked poultry exposure with fever, abdominal cramps, and risk of postinfectious Guillain-Barre syndrome.
Highly contagious dysentery with low inoculum spread in daycare or crowded settings and risk of hemolytic uremic syndrome.
Campylobacter jejuni invades intestinal mucosa causing inflammatory enterocolitis and can trigger immune-mediated neuropathy.
Shigella invades colonic epithelium and produces Shiga toxin that can injure endothelium and precipitate HUS.
Stool culture grows curved gram-negative rods in microaerophilic conditions at 42 C; stool PCR identifies Campylobacter species.
Stool PCR or culture identifies Shigella; severe toxin-mediated disease may show hemolysis, thrombocytopenia, creatinine rise, and schistocytes.
The trap
Empiric antimotility drugs in febrile bloody diarrhea can worsen outcomes; obtain stool testing and hydrate first, then use targeted antibiotics only when severe or high-risk features are present.
The repair move
Next best step: give oral rehydration or IV fluids based on volume status, avoid antimotility agents in dysentery, and start azithromycin for severe Campylobacter illness or high-risk patients while monitoring for neurologic sequelae.
Try a free question
CoreA 24-year-old man has fever, crampy abdominal pain, and bloody diarrhea two days after a cookout where he ate undercooked chicken. What is the most likely diagnosis?
Show answer and explanation
Answer: B. Campylobacter infection. Undercooked poultry exposure with febrile inflammatory diarrhea strongly suggests Campylobacter jejuni.
Why the other choices are tempting
- A. Incorrect because Shigella is more strongly linked to person-to-person low-inoculum spread than poultry exposure.
- C. Incorrect because enterotoxigenic E coli typically causes watery traveler diarrhea without dysentery.
- D. Incorrect because giardiasis usually presents with chronic greasy foul-smelling stools, not acute bloody diarrhea.
- E. Incorrect because cholera causes profuse watery rice-water stool rather than febrile bloody dysentery.
Flashcards
Tap a card to flip it.
Which exposure history most strongly points toward Campylobacter in bloody diarrhea?
Recent undercooked poultry ingestion strongly points toward Campylobacter.
What epidemiologic feature makes Shigella outbreaks common in daycare settings?
Shigella requires a very low inoculum, enabling efficient person-to-person transmission.
Quick answers
What is the fastest way to tell Campylobacter from Shigella?
Recent undercooked poultry exposure is the quickest clinical clue favoring Campylobacter.
What is the key clue for Campylobacter?
Inflammatory diarrhea after undercooked poultry exposure with fever, abdominal cramps, and risk of postinfectious Guillain-Barre syndrome.
What is the key clue for Shigella?
Highly contagious dysentery with low inoculum spread in daycare or crowded settings and risk of hemolytic uremic syndrome.
What is the common trap with Campylobacter vs Shigella?
Empiric antimotility drugs in febrile bloody diarrhea can worsen outcomes; obtain stool testing and hydrate first, then use targeted antibiotics only when severe or high-risk features are present.