Gastroenteritis

Management

Gastroenteritis is commonly viral but may also be bacterial or parasitic. In most cases, supportive care is sufficient. However, empirical antibiotics plus stool MCS (microscopy, culture, and sensitivity) should be considered if the presentation is severe or prolonged.

• Indications for Empirical Antibiotics

  • Patient is incapacitated, displaying high fever, tachycardia, or severe abdominal pain

  • Hypovolaemia due to profuse diarrhoea

  • Bloody stools or symptoms >3–7 days

  • Immunocompromised patients (e.g. HIV, chemotherapy)

• Other Considerations

  • If symptoms persist >7 days, parasites (e.g. Giardia, Cryptosporidium) become more likely

  • Viral PCR is not routinely recommended

  • Check for Cryptosporidium and Giardia in prolonged symptoms or immunodeficiency

Public Health (e.g. Nursing Home Outbreaks)

• Notify facility staff of any suspected or confirmed diarrhoeal illness promptly

• Advise residents to avoid communal areas for ≥48 hours after symptoms resolve

• If multiple residents develop gastro, staff should inform public health authorities

• Reinforce strict hand hygiene among staff and residents (soap-and-water or alcohol-based rub)

Treatment

Non-Pharmacological

• Oral Rehydration Solution (ORS): Aim for ~2–3 L/24 hours for adults (adjust for children by weight)

• Antiemetics:

  • Ondansetron (adults: 4–8 mg PO TDS; children: 0.15 mg/kg up to 8 mg)

  • Metoclopramide 10 mg TDS in adults (use with caution in <20 years due to risk of dystonic reactions)

• Anti-Diarrhoeals (adults only):

  • Loperamide 4 mg initially, then 2 mg after each loose stool (max 16 mg/day)

  • Avoid if fever, bloody stools, or suspected invasive infection

• Diet & Fluids:

  • Avoid sugary or carbonated drinks (can worsen osmotic load)

  • Continue breastfeeding for infants

  • Early refeeding with a balanced diet is recommended; no prolonged fasting

Antibiotics

• Empirical (Traveller’s Diarrhoea Protocol):

  • Ciprofloxacin 500 mg BD for 3–7 days or Norfloxacin 400 mg BD for 3–7 days

  • If resistance suspected (e.g. SE Asia), Azithromycin 500 mg OD for 3 days

• Clostridioides difficile:

  • Oral Metronidazole 400 mg TDS x 10 days (for mild/moderate)

  • Consider oral vancomycin for severe or recurrent cases, and avoid PPIs if possible

• Giardia:

  • First line: Tinidazole 2 g stat

  • Second line: Metronidazole 400 mg TDS for 5–7 days

Red Flags

• Severe abdominal pain or tenderness suggesting possible surgical cause

• Haemodynamic compromise (tachycardia, hypotension, altered consciousness)

• Bloody stools, high fever (>39°C)

• Persistent vomiting without diarrhoea (possible obstruction)

• Recent travel in immunocompromised or antibiotic use suggests more complex aetiologies

Supportive Therapy

• Antiemetics:

  • Adults: Ondansetron 4–8 mg PO or Metoclopramide 10 mg TDS

  • Children: Ondansetron 0.15 mg/kg (max 8 mg)

• Probiotics:

  • May reduce diarrhoea duration in children (e.g. Lactobacillus rhamnosus GG or Saccharomyces boulardii)

• Zinc Supplementation (Children):

  • 20 mg daily for 10–14 days if malnourished, as recommended by WHO/UNICEF guidelines

Notes

• Emphasise hand hygiene to prevent transmission.

• In older or frail patients, monitor for dehydration and electrolyte imbalances.

• Provide patient education on safe food handling, water purification if travelling.

• Review within 24–48 hours if severe or if no improvement, and consider further investigations (stool MCS, blood tests).