What is the recommended diagnostic work‑up for suspected Yersinia enterocolitis in children under five, adolescents, or adults with recent exposure to undercooked pork, contaminated water, or pet feces who present with fever, right‑lower‑quadrant abdominal pain and watery or bloody diarrhea?

Diagnostic Work-Up for Yersinia Enterocolitis

Stool culture for Yersinia enterocolitica is the primary diagnostic test and should be specifically requested in patients with persistent abdominal pain (especially school-aged children with right lower quadrant pain mimicking appendicitis) and in those with fever who have epidemiologic risk factors including exposure to raw or undercooked pork products. 1

When to Test for Yersinia

Clinical Indications (Strong Recommendations)

• Persistent abdominal pain, particularly in school-aged children presenting with right lower quadrant pain that mimics appendicitis due to mesenteric adenitis 1
• Fever with epidemiologic risk factors for yersiniosis 1
• Diarrhea accompanied by any of the following: fever, bloody or mucoid stools, severe abdominal cramping or tenderness, or signs of sepsis 1

Epidemiologic Risk Factors Requiring Testing

• Infants and young children with direct or indirect exposures to raw or undercooked pork products 1
• Recent consumption of undercooked pork 2, 3
• Exposure to contaminated water 2
• Contact with pet feces or infected animals 2

Diagnostic Testing Algorithm

Primary Diagnostic Test: Stool Culture

• Stool culture remains the gold standard for Yersinia enterocolitica diagnosis and must be specifically requested, as routine stool cultures often do not include Yersinia 1
• Cold enrichment technique at 4°C for up to 3 weeks significantly improves detection rates and should be employed when clinical suspicion is high 4
• A single diarrheal stool specimen is the optimal sample for laboratory diagnosis 5
• If timely diarrheal stool cannot be collected, a rectal swab may be used for bacterial detection 5

Blood Cultures: Critical in Specific Populations

Blood cultures should be obtained in the following circumstances 1:

• Infants <3 months of age (regardless of presentation) 1
• Any age with signs of septicemia or systemic manifestations 1
• Immunocompromised patients 1
• Patients with high-risk conditions such as hemolytic anemia 1

Serologic Testing

• Agglutination tests for Yersinia antibodies can be useful in diagnosing infection, particularly when stool cultures are negative but clinical suspicion remains high 4
• Serologic testing is especially valuable for detecting post-infectious sequelae such as reactive arthritis or erythema nodosum 3

Molecular Methods

• PCR assays can identify virulence factors including the Yersinia virulence plasmid (pYV) and are more sensitive than culture methods 4, 2
• Multiplex PCR panels detect 3-4 times more pathogens in immunocompromised populations but detect DNA/RNA, not necessarily viable organisms, requiring clinical correlation 6, 5
• Real-time PCR allows both qualitative and quantitative evaluation 2

Age-Specific Clinical Presentations

Children ≤4 Years

• Diarrhea is the predominant symptom (occurs in 95% of cases) 3
• Fever and watery or bloody diarrhea are common 3

Children 5-14 Years

• Abdominal pain in the right lower quadrant is most common (63% of cases) 3
• Presentation frequently mimics appendicitis due to mesenteric adenitis 1, 3

Adolescents and Adults

• Pseudo-appendicitis presentation is typical 3
• May present with pharyngitis and systemic symptoms 4

Critical Pitfalls to Avoid

Laboratory Communication

• Always specifically request Yersinia testing on stool cultures, as it is not included in routine bacterial stool culture panels 1
• Request cold enrichment when clinical suspicion is high, as this technique significantly improves yield 4

Specimen Handling

• Collect and preserve stool specimens appropriately for identification of virulence factors like pYV 4
• Blood culture isolates grown at 37°C may lack the pYV plasmid, while stool isolates with cold enrichment are more likely to retain it 4

Clinical Misdiagnosis

• Avoid unnecessary appendectomies: approximately 6% of yersiniosis patients ≥5 years undergo appendectomy due to misdiagnosis 3
• Consider Yersinia in patients with symptoms resembling appendicitis, especially with appropriate epidemiologic exposure 3

Post-Infectious Sequelae Recognition

• Reactive arthritis occurs in approximately 12% of yersiniosis patients (compared to 5% in unexposed populations) 3
• Erythema nodosum occurs in 3% of cases (compared to 0.1% in unexposed populations) 3
• Physicians should maintain high suspicion for recent Yersinia infection in patients presenting with unclear arthritis 3

Special Populations

Immunocompromised Patients

• Perform broad differential diagnosis with stool evaluation by culture, viral studies, and parasitic examination 1, 5
• Consider broader bacterial, viral, and parasitic testing regardless of fever or bloody stools 1

Outbreak Settings

• Test for a broader set of bacterial, viral, and parasitic agents when multiple people share common exposure 1
• Coordinate testing selection with public health authorities 1

Additional Diagnostic Considerations

Hospitalization and Disease Burden

• Approximately 27% of yersiniosis patients require hospitalization 3
• Symptoms typically last about 10 days 3
• The hospitalization rate and symptom duration justify aggressive diagnostic work-up in appropriate clinical scenarios 3

Culture-Independent Diagnostic Testing

• When positive results are obtained by multiplex molecular tests, specimens should be cultured if isolate submission is required under public health reporting rules or when antimicrobial susceptibility testing would affect care 5
• Clinical correlation is essential when interpreting molecular test results, as these detect genetic material rather than viable organisms 5