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 give a formulary choice proton pump inhibitor (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

or

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

Penicillin allergy

• 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

If people are still symptomatic after first-line treatment:

• Formulary choice proton pump inhibitor every 12 hours, plus
• Amoxicillin 1g every 12 hours, plus
• Metronidazole 400mg every 12 hours or clarithromycin 500mg every 12 hours, whichever was not used first-line

If the above treatments have failed, will not work due to resistance, or are unsafe to use in an individual patient, or penicillin allergic:

• Formulary choice proton pump inhibitor every 12 hours, plus
• Metronidazole 400mg every 12 hours, plus
• Levofloxacin 250-500mg every 12 hours (unlicensed)
  • Systemic fluoroquinolones must now only be prescribed when other commonly recommended antibiotics are inappropriate (See MHRA Drug Safety Updates below)
  • Patients should be advised to stop treatment at the first signs of a serious adverse reaction, such as tendinitis or tendon rupture, muscle pain, muscle weakness, joint pain, joint, feet, or abdomen swelling, peripheral neuropathy, rapid onset of shortness of breath, new-onset of heart palpitations, and central nervous system effects: including new or worsening depression or psychosis, and to seek immediate medical attention.

Drug Safety Updates for Levofloxacin (refer to 5.1.12 Quinolones for further details).

• MHRA Drug Safety Update (November 2018): Systemic and inhaled fluoroquinolones: small increased risk of aortic aneurysm and dissection; advice for prescribing in high-risk patients.
• MHRA Drug Safety Update (December 2020): Systemic and inhaled fluoroquinolones: small risk of heart valve regurgitation; consider other therapeutic options first in patients at risk.
• MHRA Drug Safety Update (September 2023): Fluoroquinolone antibiotics: suicidal thoughts and behaviour.
• MHRA Drug Safety Update (January 2024): Fluoroquinolone antibiotics: must now only be prescribed when other commonly recommended antibiotics are inappropriate.

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 immunocompromised or systemically unwell discuss antimicrobial treatment with microbiology.

Notify all confirmed and suspected cases of food poisoning: https://www.gov.uk/guidance/notifiable-diseases-and-causative-organisms-how-to-report

The information below is largely based on NICE NG199 Clostridioides difficile infection: antimicrobial prescribing (July 2021), but has been refined with local specialist input.

Please see Public Health England's guidance on the diagnosis and reporting of C. difficile

Ensure prompt submission of stool sample for testing if C. difficile infection is suspected. Note any history of antibiotic treatment on request form, and specifically request C. difficile testing as this is not routinely done on community specimens from patients under 65 years of age.

Treating suspected or confirmed C. difficile infection

For people with suspected or confirmed C. difficile infection, assess:

• whether it is a first or further episode (relapse or recurrence) of C. difficile infection
• the severity of C. difficile infection
• individual factors such as age, frailty or comorbidities that may affect the risk of complications or recurrence

Review existing antibiotic treatment and stop it unless essential. If an antibiotic is still essential, seek advice from a microbiologist for an alternative with a lower risk of causing C. difficile infection.

Review the need to continue any treatment with:

• proton pump inhibitors
• other medicines with gastrointestinal activity or adverse effects, such as laxatives
• medicines that may cause problems if people are dehydrated, such as non-steroidal anti-inflammatory drugs (NSAIDs), angiotensin-converting enzyme inhibitors, angiotensin 2 receptor antagonists and diuretics

For all patients, local specialists suggest seeking prompt advice from a microbiologist regarding management, especially if the patient still requires antibiotic treatment for another indication. Do not delay initiation of treatment for C. difficile.

Advise all people with suspected or confirmed C. difficile infection about:

• drinking enough fluids to avoid dehydration
• preventing the spread of infection
• seeking medical help if symptoms worsen rapidly or significantly at any time
• avoiding the use of antimotility drugs (such as loperamide) to treat diarrhoeal symptoms

First episode of mild, moderate, or severe C. difficile infection

Patients with severe or life-threatening infection should be urgently referred to hospital (see reassessment and referral below)

When considering antibiotic treatment with vancomycin or fidaxomicin in primary care, it may be appropriate to contact community pharmacy to ensure supply is available within an adequate timeframe. Vancomycin 125mg capsules are included in the 2020/21 NHS England South West Enhanced Service for the Availability of Specialist Medicines and should be available from participating community pharmacies. Please note this is an enhanced service that is not available from all community pharmacies. A list of the pharmacies signed up to this service is available here.

1st line antibiotic

For all patients, prompt advice regarding management should be sought from a microbiologist or infectious diseases specialist, however treatment initiation should not be delayed whilst awaiting specialist advice

Vancomycin is the preferred choice as it has superior efficacy to metronidazole in the treatment of C. difficile infection

Vancomycin

• Adults (aged ≥ 18 years): 125mg orally four times a day for 10 days
• Children (aged <18 years): refer to BNFC
• For those unable to swallow capsules, alternative oral formulations may be available (do not use the parenteral route), seek specialist advice

OR

Metronidazole

• Vancomycin is the preferred choice as it has superior efficacy to metronidazole in the treatment of C. difficile infection. Metronidazole may be considered for mild cases (unless considered to be at high risk of relapse*), when other treatment options are not readily available
• Adults (aged ≥ 18 years): 400mg orally three times a day for 10-14 days
• Children (aged <18 years): refer to BNFC
• Metronidazole oral suspension is not recommended for C. difficile infection (theoretical risk that efficacy of metronidazole benzoate may be compromised because of reduced exposure to gastric enzymes).

2nd line antibiotic

Fidaxomicin

• Adults and children with body-weight ≥ 12.5kg: 200mg orally twice a day for 10 days
• Individuals with swallowing difficulties or body-weight <12.5kg: oral suspension given twice a day for 10 days (dose dependent on weight – refer to drug entry)
• Use of fidaxomicin should be discussed with a microbiologist, infectious diseases specialist or gastroenterologist. It should be considered for patients at high risk of relapse*.

* Patients considered to be at high risk of relapse are those who require ongoing antibiotic therapy for other indications and those with historic episodes of C. difficile infection. If in doubt, seek advice from microbiology

Further episodes of C. difficile infection (relapses or recurrent episodes)

Patients with severe or life-threatening infection should be urgently referred to hospital (see reassessment and referral below)

NICE NG199 defines a relapse as occurring within 12 weeks of previous symptom resolution and recurrence as occurring more than 12 weeks after previous symptom resolution.

When considering antibiotic treatment with vancomycin or fidaxomicin in primary care, it may be appropriate to contact community pharmacy to ensure supply is available within an adequate timeframe. Vancomycin 125mg capsules are included in the 2020/21 NHS England South West Enhanced Service for the Availability of Specialist Medicines and should be available from participating community pharmacies. Please note this is an enhanced service that is not available from all community pharmacies. A list of the pharmacies signed up to this service is available here.

Relapse

Fidaxomicin

• Adults and children with body-weight ≥ 12.5kg: 200mg orally twice a day for 10 days
• Individuals with swallowing difficulties or body-weight <12.5kg: oral suspension given twice a day for 10 days (dose dependent on weight – refer to drug entry)
• Use of fidaxomicin should be discussed with a microbiologist, infectious diseases specialist or gastroenterologist.

Recurrence

Seek specialist advice regarding appropriate choice of antibiotic for all patients with recurrent episodes of C. difficile infection.

For recurrent episodes of C. difficile infection in adults who have had 2 or more previous episodes, refer to specialists for consideration of alternative treatments including faecal microbiota transplant.

Fidaxomicin

• Adults and children with body-weight ≥ 12.5kg: 200mg orally twice a day for 10 days
• Individuals with swallowing difficulties or body-weight <12.5kg: oral suspension given twice a day for 10 days (dose dependent on weight – refer to drug entry)

OR

Vancomycin

• Adults (aged ≥ 18 years):
  • 125mg orally four times a day for 10 days
  • A tapering course of vancomycin may be recommended to prevent further relapses or recurrences (seek specialist advice):
    • 125mg every 6 hours for 14 days, then every twelve hours for one week, then once daily for one week, then every other day for one week, then every three days for 2 weeks

• Children (aged <18 years):
  • refer to BNFC
  • A tapering course of vancomycin may be recommended to prevent further relapses or recurrences (seek specialist advice):
    • 10mg/kg (max 125mg) every 6 hours for 10 to 14 days, then every 12 hours for one week, then once daily for one week, then every other day for two to three weeks
• For those unable to swallow capsules, alternative oral formulations may be available (do not use the parenteral route), seek specialist advice

See 5.1.7 Some other antibacterials and 5.1.11 Metronidazole

Reassessment and referral

Reassess people with suspected or confirmed C. difficile infection if symptoms or signs do not improve as expected, and refer to hospital if they are severely unwell, or their symptoms or signs worsen rapidly or significantly at any time.

Use clinical judgement to determine whether antibiotic treatment for C. difficile is ineffective. It is not usually possible to determine this until day 7 because diarrhoea may take 1 to 2 weeks to resolve.

Patients with severe or life-threatening infection should be urgently referred to hospital. Signs include:

• white cell count (WCC) greater than 15 × 10⁹ per litre
• acutely increased serum creatinine concentration (greater than 50% increase above baseline)
• a temperature higher than 38.5^oC
• abdominal signs suggesting evidence of severe colitis
• hypotension
• signs or symptoms suggesting partial or complete ileus
• signs or symptoms suggesting toxic megacolon

Refer adults with 2 or more previous episodes of C. difficile infection to specialists for consideration of alternative treatments including faecal microbiota transplant.

Consider referring people in the community to hospital if they could be at high risk of complications or recurrence because of individual factors such as age, frailty, or comorbidities

Giardiasis can be transmitted by person-to-person spread by the faecal-oral route, by contact with the faeces of infected animals, by consumption of contaminated food or drink, waterborne including swimming in contaminated water, or by sexual transmission, particularly among men who have sex with men.

Many cases are associated with recent foreign travel, particularly from South Asia, and it is the most identified pathogen in returning travellers with prolonged diarrhoea.

Diarrhoea is the most common symptom of giardiasis. Other symptoms include abdominal cramps, bloating, flatulence, malaise, loss of appetite, and rarely nausea. Malabsorption, weight loss, and faltering growth may occur in children.

Suspected giardiasis

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.
  • If related to recent foreign travel, include travel destination on laboratory request form and specifically request ova, cysts, and parasites (OCP).

Advise all people with suspected or confirmed giardiasis infection about:

• Drinking enough fluids to avoid dehydration.
• Preventing the spread of infection (detailed information on personal hygiene, environmental cleaning, and disposal of soiled materials, can be found here)
  • Advise the person that they should not go swimming for 2 weeks after the last episode of diarrhoea.
• Seeking medical help if symptoms worsen rapidly or significantly at any time.
• Avoiding the use of antimotility drugs (such as loperamide) to treat diarrhoeal symptoms.
• A period of lactose intolerance may occur following giardiasis which may last several weeks.
  • Consider a lactose-free diet for one month after treatment followed by a gradual reintroduction when symptoms settle.

Following positive stool sample result

Notify the local health protection team immediately of confirmed giardiasis by completing a notification form.

Screen all household and sexual contacts for giardia as household members may have asymptomatic infection.

Metronidazole

• Adults and children over 10 years of age:
  • 2g once daily for 3 days, or 400mg 3 times a day for 5 days
• Children 1 to 9 years of age (doses given once daily for 3 days):
  • 1 – 2 years: 500mg
  • 3 – 6 years: 600–800mg
  • 7 – 9 years: 1g

See section: 5.1.11 Metronidazole

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

If metronidazole is not appropriate or not tolerated seek specialist advice.

Pregnancy or breastfeeding

In the case of pregnancy or breastfeeding discuss with a microbiologist or infection specialist.

Treatment failure

Discuss compliance with metronidazole course, consider repeating metronidazole treatment as above if treatment course was not completed. If metronidazole is not appropriate or not tolerated seek specialist advice.

Recurrence or reinfection

If recurrence of symptoms occurs:

• Review screening:
  • Check all household and sexual contacts for giardia as household members may have asymptomatic infection.
  • Pets can be a source of giardia carriage so patients should consider discussing screening with their veterinarian.
• Consider repeating metronidazole treatment as above or seek specialist advice.
• Alternative unlicensed treatments may only be available from secondary care.

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

Send stool culture.

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.

Adults and children over 6 months

Mebendazole

• 100mg 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.

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

If standby treatment appropriate give:

• Ciprofloxacin 500 mg twice a day for 3 days (private prescription only, not on FP10).
• MHRA Drug Safety Update (November 2018): Systemic and inhaled fluoroquinolones: small increased risk of aortic aneurysm and dissection; advice for prescribing in high-risk patients
• MHRA Drug Safety Update (March 2019): Fluoroquinolone antibiotics: new restrictions and precautions for use due to very rare reports of disabling and potentially long-lasting or irreversible side effects
• MHRA Drug Safety Update (December 2020): Systemic and inhaled fluoroquinolones: small risk of heart valve regurgitation; consider other therapeutic options first in patients at risk

See section: 5.1.12 Quinolones

The pathophysiology of acute cholecystitis is cystic duct obstruction, which causes an acute sterile inflammation. Secondary infection of the gallbladder space by bacteria may follow.

Doxycycline

• 200mg single dose, then 100mg daily for total of 7 days

plus

Metronidazole

• 400mg every 8 hours for 7 days

NICE has published a guideline on diagnosis and management of diverticular disease (see NG147 here).