Gastroenteritis
Gastroenteritis including traveller's diarrhoea
- Acute diarrhoea is usually defined as three or more episodes of liquid or semi-liquid stool in a 24-hour period, lasting for less than 14 days
- If specific aetiology is known or suspected, see below
- If C diff is suspected, refer to Clostridioides difficile Infection guideline
- Consider inflammatory bowel disease (IBD) in cases of type 6 and 7 stool (according to the Bristol stool chart) accompanied by blood and mucus AND if symptoms persist for more than 14 days. Urgent (same day) referral to gastroenterology is imperative for these cases.
- For information regarding infection prevention and control, see ‘Gastroenteritis at-a-glance‘
- Complete the notification form immediately on diagnosis of a suspected notifiable disease. See Notifiable diseases section for more information.
- Obtain a detailed travel history and any history of immunosuppression
Indications for antimicrobials
Majority of cases of acute diarrhoea are self-limiting and require NO antimicrobial therapy. Rehydration and electrolyte replacement (oral rehydration solution e.g. dioralyte) is preferred
Antimicrobials should be considered for any of the following:
- Severe illness (fever more than or equal to 38.5°C, hypovolemia, more than or equal to 6 unformed stools per 24 hours, severe abdominal pain)
- An immunocompromised host
Send a faeces PCR & MCS prior to commencing antimicrobials and send blood cultures if fever more than 38.5ºC
If relevant travel history or suggestive symptoms are present, additionally request a Cryptosporidium/Giardia/Entamoeba faeces PCR
Consider referral to Micro/ID if starting antimicrobial treatment
Empiric Therapy
preferred
azithromycin 500mg po od for 3 days
Specific pathogens isolated from stool
- Specific pathogens should ONLY be treated if symptoms are on-going or worsening and after discussion with Micro/ID.
- If symptoms have resolved, treatment is not normally indicated.
- At-risk groups include pregnant women, older adults (over 60 years) and immunocompromised adults (Salmonella, Cryptosporidiosis, Giardiasis)
Bacterial pathogens identified in faeces
Salmonella spp
azithromycin 1g po for 1 dose and then 500mg po od for 3 days.
Extend to 7 days in immunocompromised patients.
Salmonella can infect aortic aneurysms. Consider extending treatment duration for up to 2 weeks
Campylobacter spp or Shigella spp
azithromycin 500mg po od for 3 days
E. coli (STEC) e.g. O157:H7
Painful bloody diarrhoea. Do NOT give antibiotics as this is associated with the development of haemolytic uraemic syndrome (HUS). Consult Micro/ID.
Protozoal pathogens identified in faeces
Giardia lamblia (cysts or trophozoites seen OR antigen detected)
metronidazole 2g od po for 3 days
Entamoeba histolytica (cysts or trophozoites seen OR positive serology)
metronidazole 800mg tds po 5 days. Discuss need for luminal treatment with Micro/ID.
Cryptosporidium parvum
no clear effective treatment. Typically self-limiting in immunocompetent patients. Discuss with Micro/ID.
Viral pathogens identified in faeces
There is generally no effective anti-viral therapy for viral pathogens identified in faeces such as Norovirus or Adenovirus. Preferred management is rehydration and electrolyte replacement. For immunocompromised patients with chronic norovirus, consult Micro/ID.