What are the most likely differentials for a young to middle-aged adult with no significant medical history who presents with belching, abdominal pain, and diarrhea after consuming street food?

Differential Diagnoses for Post-Street Food Gastrointestinal Symptoms

The most likely diagnosis is acute infectious gastroenteritis, specifically bacterial foodborne illness from contaminated street food, with Salmonella, Campylobacter, E. coli, and norovirus being the primary pathogens to consider. 1, 2

Primary Differential Diagnoses

Acute Bacterial Foodborne Illness (Most Likely)

• Bacterial pathogens account for the majority of foodborne illnesses following street food consumption, with Salmonella, E. coli, Campylobacter, and Listeria being the most common causative organisms 1, 2
• The triad of belching, abdominal pain, and diarrhea occurring after street food intake strongly suggests bacterial gastroenteritis, which affects approximately one in six Americans annually 2
• Bacterial etiology is found in 5-17% of adults presenting with acute diarrhea to emergency departments, with higher likelihood when accompanied by abdominal pain 1
• The incubation period varies by pathogen but typically ranges from hours to 2-3 days after contaminated food consumption 1, 2

Viral Gastroenteritis

• Norovirus is the leading cause of epidemic foodborne illness and can be transmitted through contaminated food, particularly in settings with suboptimal food handling practices 2, 3
• Viral gastroenteritis presents with nausea, vomiting, abdominal pain, and diarrhea, though vomiting tends to be more prominent than in bacterial infections 4, 5
• Adenovirus serotypes 40 and 41 can cause GI symptoms with diarrhea being more prominent than vomiting, though these primarily affect children under 2 years 4
• The majority of viral gastroenteritis cases are self-limited and resolve without specific intervention 6, 7

Food Intolerance or Hypersensitivity

• Carbohydrate malabsorption from lactose or fructose in street food ingredients can cause belching, abdominal pain, and diarrhea through osmotic effects 1
• Alpha-gal syndrome should be considered if the patient consumed mammalian meat from street vendors and lives in tick-prevalent regions (Southeast, mid-Atlantic, Midwest US) 1
• Alpha-gal syndrome presents with GI symptoms 1-4 hours after mammalian meat consumption, including abdominal pain, diarrhea, nausea, and vomiting, often without skin or respiratory symptoms 1
• Food protein-induced enterocolitis syndrome (FPIES) is less likely in adults but presents with vomiting 1-4 hours after food ingestion and diarrhea within 5-10 hours 1

Critical Diagnostic Approach

History Elements to Prioritize

• Timing of symptom onset relative to food consumption helps differentiate bacterial (6-72 hours), viral (12-48 hours), and allergic etiologies (1-4 hours for alpha-gal) 1, 2
• Presence of fever and bloody diarrhea increases likelihood of invasive bacterial pathogens like Salmonella, Campylobacter, or Shigella 1
• Travel history and geographic location matter for alpha-gal syndrome (tick-endemic areas) and specific bacterial pathogens 1
• Recent antibiotic use raises concern for Clostridium difficile, though this should be tested in all new presentations of diarrhea regardless of antibiotic history 1

Physical Examination Priorities

• Assess for volume depletion through vital signs, orthostatic changes, mucous membrane moisture, and skin turgor 8, 2
• Abdominal examination should evaluate for peritoneal signs, which would suggest more serious pathology requiring imaging 8
• Fever suggests bacterial or invasive pathogen rather than simple viral gastroenteritis 1, 2

Laboratory and Diagnostic Testing

• Stool culture should be obtained if the patient has bloody diarrhea, fever, severe abdominal pain, or signs of volume depletion 1
• Testing for Clostridium difficile is recommended in all new presentations of diarrhea, regardless of antibiotic exposure history 1
• Complete blood count, serum albumin, and C-reactive protein can help assess severity and guide management 1
• Alpha-gal IgE antibody testing should be performed if the patient consumed mammalian meat and lives in or has traveled to tick-endemic regions 1
• Stool testing for ova and parasites may be appropriate based on exposure history and symptom duration 1

Management Approach

Immediate Management

• Rehydration is the cornerstone of treatment, either oral rehydration for mild-moderate cases or intravenous fluids for severe dehydration 2, 6
• Empiric antibiotic therapy should be reserved for patients with severe symptoms, bloody diarrhea, fever, or immunocompromised status 1, 2
• Do not delay empiric treatment while awaiting stool culture results if bacterial foodborne illness is strongly suspected based on clinical presentation 2

Specific Considerations

• If alpha-gal syndrome is confirmed with elevated IgE, initiate strict mammalian meat avoidance diet and counsel on avoiding further tick bites 1
• Antibiotic selection should be guided by local resistance patterns when empiric therapy is indicated 1
• Report suspected foodborne illness to local and state health agencies as requirements vary by jurisdiction 2

Common Pitfalls to Avoid

• Do not assume viral etiology without considering bacterial causes, especially with street food exposure and presence of fever or bloody diarrhea 1, 2
• Avoid routine stool testing in mild, self-limited cases without risk factors, as this is wasteful and unlikely to change management 7
• Do not miss alpha-gal syndrome by failing to ask about geographic location and tick exposure in patients with delayed GI symptoms after meat consumption 1
• Recognize that belching alone can be a manifestation of gastric belching related to gastritis or GERD, which may coexist with infectious gastroenteritis 1, 9
• Do not overlook C. difficile testing even in patients without recent antibiotic use, as community-acquired cases are increasing 1