What is the most likely diagnosis and recommended management for an adult with acute food‑borne gastroenteritis presenting with fever, watery diarrhea, abdominal cramping and nausea/vomiting?

Management of Acute Food Poisoning with Fever and Loose Stools

For an adult with food poisoning presenting with fever, loose stools, and abdominal pain, the primary treatment is oral rehydration therapy with early refeeding, while antibiotics should only be considered if fever is high (≥38.5°C), bloody diarrhea is present, or the patient shows signs of severe illness. 1

Immediate Assessment Priorities

Evaluate hydration status first by checking for:

• Dry mucous membranes, decreased skin turgor, prolonged capillary refill (>2 seconds), cool extremities, or altered mental status indicating moderate to severe dehydration 2
• Vital signs including temperature, pulse, and blood pressure 2
• Stool characteristics: watery versus bloody, presence of mucus 2

When to Perform Diagnostic Testing

Routine stool cultures and laboratory workup are NOT recommended for most patients with acute watery diarrhea. 1 Testing should be reserved for:

• Fever with bloody or mucoid stools (suggests Salmonella, Shigella, Campylobacter) 2
• Severe dehydration or signs of sepsis 1
• Symptoms persisting ≥14 days 2
• Immunocompromised status 2
• Recent travel to endemic areas 2

People with fever or bloody diarrhea should be evaluated for enteropathogens for which antimicrobial agents may confer clinical benefit including Salmonella, Shigella, and Campylobacter. 2

Primary Treatment: Rehydration

Oral Rehydration Solution (ORS)

• First-line therapy for mild to moderate dehydration 1
• Continue ORS until clinical dehydration is corrected, then switch to maintenance fluids 2
• Replace ongoing stool losses with ORS until diarrhea resolves 2

Intravenous Fluids

Reserved for:

• Severe dehydration with altered mental status 2
• Failure of oral rehydration therapy 2
• Presence of ileus 2
• Continue IV fluids until pulse, perfusion, and mental status normalize 2

Nutritional Management

• Resume age-appropriate usual diet immediately after rehydration is completed 2
• Early refeeding is preferred over prolonged fasting 3
• No need to restrict diet to bland foods 2

Antibiotic Therapy: When and What

Indications for Empiric Antibiotics

Empiric antimicrobial therapy is NOT recommended for most immunocompetent patients with acute watery diarrhea. 1 Consider antibiotics only when:

• Documented fever in medical setting PLUS abdominal pain PLUS bloody diarrhea (bacillary dysentery) 1
• Recent international travel with temperature ≥38.5°C or signs of sepsis 1
• Immunocompromised patients with severe illness and bloody diarrhea 1

Antibiotic Choices

For adults with suspected bacterial dysentery:

• First-line: Azithromycin 500-1000 mg single dose (preferred due to rising fluoroquinolone resistance) 4
• Alternative: Ciprofloxacin 500 mg twice daily for 3 days or levofloxacin 500 mg once daily for 3 days 4

For specific pathogens (if identified):

• Shigella: Fluoroquinolone or azithromycin 500 mg daily 2
• Campylobacter: Azithromycin 500 mg daily (preferred due to 19% fluoroquinolone resistance) 2
• Salmonella (non-typhoidal): Ciprofloxacin 500 mg twice daily, or amoxicillin if susceptible 2

Symptomatic Treatment

Antimotility Agents

• Loperamide may be given to immunocompetent adults with acute watery diarrhea 2
• CRITICAL PITFALL: Never use loperamide in bloody diarrhea, fever, or suspected STEC infection due to risk of hemolytic uremic syndrome and toxic megacolon 2, 1
• Loperamide combined with antibiotics can further reduce symptom duration 4

Antiemetics

• Ondansetron may be given to facilitate oral rehydration in patients with significant vomiting 2
• Use only after adequate hydration is ensured 2

Special Considerations

Enteric Fever (Typhoid)

If fever is prominent with or without diarrhea AND patient has:

• Recent travel to endemic areas (South Asia, Africa) 2
• Consumed food prepared by someone with recent endemic exposure 2

Start empiric broad-spectrum antibiotics immediately after blood and stool cultures (do not delay treatment) 5

Clostridium difficile

Consider if:

• Recent antibiotic use within 8-12 weeks 2
• Healthcare-associated diarrhea 2
• Test specifically for C. difficile toxin 2

Critical Pitfalls to Avoid

1. Do not routinely order stool cultures in uncomplicated acute watery diarrhea without alarm features 1
2. Do not give empiric antibiotics for simple acute watery diarrhea in immunocompetent patients 1
3. Never use loperamide with bloody diarrhea or suspected STEC 1
4. Do not use antimotility drugs in children <18 years 2
5. Do not delay antibiotic therapy while awaiting cultures if enteric fever with sepsis is suspected 5

When to Reassess

• If symptoms persist ≥14 days, consider non-infectious causes (IBS, IBD) and parasitic infections 2, 1
• If fever persists despite treatment, obtain blood cultures and consider bacteremia 2
• If severe abdominal pain develops, evaluate for complications (toxic megacolon, perforation) 2