Gastro-intestinal tract infections

Clostridium difficile

Eradication of H. pylori

For people who test positive for H. pylori the following regimens should be taken for 7 days

Take into account previous exposure to clarithromycin, metronidazole or a quinolone, do not use if used in the past year for any infection.

Always use a formulary choice proton pump inhibitor (PPI) (see section 1.3.5 Proton pump inhibitors (PPI)) every 12 hours

1st line treatment

  • Formulary choice proton pump inhibitor every 12 hours, plus
  • Amoxicillin 1g every 12 hours and metronidazole 400mg every 12 hours


  • Amoxicillin 1g every 12 hours and clarithromycin 500mg every 12 hours

If allergic to penicillin:

  • Formulary choice proton pump inhibitor every 12 hours, plus
  • Clarithromycin 500mg every 12 hours and metronidazole 400mg every 12 hours

See NICE CG184: Gastro-oesophageal reflux disease and dyspepsia in adults: investigation and management (November 2014), for people allergic to penicillin and who have previous exposure to clarithromycin.

2nd line treatment

  • Formulary choice proton pump inhibitor every 12 hours, plus
  • Metronidazole 400mg every 12 hours, plus
  • Levofloxacin 250-500mg every 12 hours (unlicensed)

See NICE CG184 for people who are penicillin allergic and have prior quinolone exposure.

See NICE CG184 for people who have previous exposure to clarithromycin and metronidazole.

Consider referral to a specialist service, people with H. pylori that has not responded to second-line eradication therapy.

PPI therapy should only be continued after H pylori eradication in the case of active peptic ulceration. Continue once daily PPI therapy for one month for duodenal ulcers and two months for gastric ulcers.


Antibiotic therapy is usually not indicated unless systemically unwell and then should be based on stool culture result

If Salmonella treat and discuss with microbiology in a child under 3 months old, those over the age of 55 or immunosuppressed, or severe invasive disease.

Notify all confirmed and suspected cases of food poisoning:

Contact Public Health England: 0300 3038162


Diarrhoea is the most common symptom of giardiasis. Other symptoms include abdominal cramps, bloating and flatulence. Many cases are associated with foreign travel.

If giardiasis is suspected, especially if there is recurrent or prolonged diarrhoea (over 14 days) or travel to at-risk areas, send up to three faecal specimens at least two days apart for testing. Ova, cysts, and parasites (OCP) are shed intermittently; repeat testing may be necessary to detect the parasite in symptomatic patients.

To ensure correct tests are performed, include travel destination and reason for sending sample on laboratory request form and specifically request OCP.

  • Adults and children 12 years and above: 2 g for 1 single dose
  • Children 1 month – 11 years: 50–75 mg/kg (max. per dose 2 g) for 1 single dose
  • Adults and children over 10 years: 2 g once daily for 3 days, or 400 mg 3 times a day for 5 days
  • Children 7 – 9 years: 1 g once daily for 3 days.
  • Children 3 – 6 years: 600–800 mg once daily for 3 days.
  • Children 1 – 2 years: 500 mg once daily for 3 days (note 500mg strength tablets are non-formulary)

Alcohol should be avoided for 72 hours after tinidazole and at least 48 hours after metronidazole treatment, because of the possibility of a disulfiram-like reaction (flushing, abdominal cramps, vomiting, tachycardia).

In the case of pregnancy – consult with microbiology.

Treatment failure should be discussed with or referred to a specialist, who should exclude underlying problems.

Infectious (bloody) diarrhoea

Bloody diarrhoea may be a sign of verotoxingenic E coli enteritis (VTEC/0157 disease). Always send a stool sample from children or elderly with acute painful or bloody diarrhoea to exclude E. coli 0157 infection. If unwell consider haemolytic uraemic syndrome (HUS). Antibiotics are generally contraindicated in E. coli 0157 infections/HUS.

Primary care practitioners are recommended to always seek urgent specialist advice whenever a child or elderly are reported to have had a single episode of bloody diarrhoea. Referral is an emergency where, significant dehydration, acute abdominal pain, or signs and symptoms indicating a differential diagnosis that includes the possible need for surgical intervention, are present.

Antibiotic therapy not indicated unless systemically unwell.

Do not use anti-motility agents and assess/treat dehydration in every child or elderly person. See NICE CG84: Diarrhoea and vomiting caused by gastroenteritis in under 5s: diagnosis and management (April 2009), for further guidance


Refer to CKS website for further details

Treat all household contacts at the same time plus advise hygiene measures for 2 weeks (hand hygiene, pants at night, morning shower) plus wash sleepwear, bed linen, dust, and vacuum on day one.

For children less than 6 months of age, use hygiene measures alone. Advise cleaning the bottom gently but thoroughly at each nappy change. Advise parents to wash their hands thoroughly before and after each nappy change.

Adults and children over 6 months

  • 100mg as a single dose (off label if under 2 years of age)

If reinfection occurs a second dose may be needed after 2 weeks

Children under 6 months

Mebendazole not licensed in this age group but 6 weeks strict hygiene may be sufficient to clear infection and prevent re-infection.

Traveller’s diarrhoea

Only consider standby antibiotics for remote areas or people at high-risk of severe illness with travellers' diarrhoea.

Many anti-diarrhoea treatments are cheap to buy and are readily available, along with advice, from pharmacies. Please click here for further information and a patient leaflet

If standby treatment appropriate give:

  • Ciprofloxacin 500 mg twice a day for 3 days (private prescription only, not on FP10).


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