Which infection can cause diarrhea followed by chest pain in one relative and a transient throat rash followed by chest pain the next day in another relative?

Campylobacter jejuni Infection

Based on the clinical presentation of diarrhea followed by chest pain in multiple family members, the most likely diagnosis is Campylobacter jejuni-associated myopericarditis. This bacterial infection classically presents with gastroenteritis followed 1-3 days later by cardiac inflammation, which can manifest as chest pain 1, 2, 3.

Clinical Presentation Pattern

The sequence you describe—diarrhea preceding chest pain by approximately one day—is pathognomonic for C. jejuni myopericarditis:

• Initial phase: Watery diarrhea (typically 5-6 episodes daily), abdominal pain, and fever lasting 2-4 days 2
• Cardiac phase: Retrosternal or pleuritic chest pain developing 24-72 hours after gastrointestinal symptoms begin 1, 3
• Rash: While less common, systemic manifestations including transient rashes can occur with C. jejuni infection

The fact that multiple family members are affected with similar temporal progression strongly suggests a common infectious source, which is typical for C. jejuni (often from contaminated food or water).

Why This Diagnosis Fits

C. jejuni is one of the most common causes of bacterial gastroenteritis, but cardiac involvement occurs in only 0.4% of cases 2. The mechanism involves either direct bacterial invasion or immune-mediated inflammation of the myocardium and pericardium. The insidious presentation makes it frequently underdiagnosed 2.

Key distinguishing features from other causes:

• COVID-19: While COVID-19 can cause both GI symptoms and chest pain 4, the diarrhea prevalence is only 7.7% and typically occurs concurrently with respiratory symptoms, not as a prodrome. The transient throat rash doesn't fit COVID-19's typical presentation.

• Group A Streptococcus/Scarlet Fever: Could explain the throat rash and systemic symptoms 5, 6, but diarrhea is not a prominent feature, and the temporal sequence doesn't match.

Diagnostic Approach

Look for these specific findings:

Cardiac evaluation:

• ECG showing ST-segment elevations (mimicking STEMI) 1, 3
• Elevated troponins (typically 1-2 ng/mL range) 3
• Elevated inflammatory markers (CRP, ESR)
• Echocardiogram may show reduced ejection fraction or pericardial effusion 1
• Critical: Coronary angiography will be non-obstructive—this distinguishes myopericarditis from acute coronary syndrome 1, 2

Microbiological confirmation:

• Stool culture for Campylobacter species (gold standard) 1, 2, 7, 3
• Blood cultures if patient appears septic

Management Algorithm

1. Rule out acute coronary syndrome first with ECG, troponins, and if indicated, coronary angiography 2

2. Once ACS excluded, initiate treatment:

   • Colchicine for pericardial inflammation 1
   • Fluoroquinolone (levofloxacin 500mg daily) or macrolide (azithromycin 500mg daily) for 7-10 days 1, 2
   • Guideline-directed heart failure therapy if reduced ejection fraction present 1

3. Avoid harmful interventions: Recognition of this diagnosis prevents unnecessary fibrinolysis or invasive procedures that could cause iatrogenic complications 2

Critical Pitfalls

• Don't dismiss the diarrhea as unrelated to chest pain—the temporal relationship is diagnostic
• Don't assume viral myocarditis without obtaining stool cultures in patients with recent gastroenteritis 3
• Don't perform unnecessary coronary interventions once non-obstructive disease is confirmed 2
• The generally favorable prognosis means aggressive cardiac interventions are rarely needed, but antibiotics are essential 2

The prognosis is typically excellent with appropriate antibiotic therapy and supportive cardiac care 2, 3.