Acute Gastroenteritis (incl C Diff)

Key facts:

Authors: Neerav Joshi, Lucia Macken, Natalie Acors and Jayne Eaden
Top Tip: Gastroenteritis can be a mild self-limiting disease. But some cases (including C Diff, CDI) can be life-threatening

Key Differential Diagnoses

• Inflammatory colitis
• Ischaemic colitis (AF, elderly, ill, pain)
• Colonic carcinoma/diverticular disease
• 'Complicated gastroenteritis' = Haemolytic-Uraemic Syndrome (eg O157 E Coli), or causing DIC

Key Investigations

• FBC, CRP
• U+E, LFT, Bone, Glucose
• BC, Stool culture (?CDI)
• AXR

Key Treatment

• IV fluids
• ± PO METRONIDAZOLE 800 mg stat, then 400 mg tds, for 14d ± PO VANCOMYCIN 125mg 6-hourly for 14d (CDI)
  Note: If patients are admitted, they should go to a side room to prevent cross infection in the hospital environment

Key Management Decisions

• Admit/not
• Antibiotics (not usually necessary; use if CDI)
• Steroids ± surgery (CDI)

Background

Mild acute gastroenteritis does not require admission, or any treatment; it is a self-limiting disease

Introduction

• Acute gastroenteritis can be a mild self-limiting disease but some cases can be life threatening with severe fluid losses and electrolyte imbalances
• Acute infective gastroenteritis usually has a rapid onset (vs inflammatory colitis)
• Pyrexia may be present but its absence should not exclude diagnosis
• Most cases are mild and self-limiting, requriing supportive care only
• But some pathogens are extremely virulent and can cause rapidly progressing life-threatening disease
• Rectal bleeding is often present and should be looked for when taking the history and in the examination – digital rectal examination (DRE) is essential
• C.difficile infection (CDI; 'C diff')) remains the most important cause of hospital-acquired diarrhoea and must be part of the differential diagnosis. Current or recent antibiotic use is the main risk factor for developing CDI.  This risk persists for up to 3 months after antibiotic use
• CDI can cause pseudomembranous colitis and present as bloody diarrhoea (like colitis). It has been associated with almost all AB, except aminoglycosides
• For CDI, quinolones are probably the worse culprits. It can be complicated by toxic megacolon (high mortality) and perforation (very high)
• Prognosis is good in mild cases; but mortality of CDI = 5-10%, 50% for severe cases; 5% need surgery (operative mortality 30%). If you suspect CDI on admission, and the patient is unwell, ask for early senior surgical review
• Ischaemic colitis (elderly, AF) can be missed, with fatal consequences
• 3-5% of the normal population carry C diff in their normal gut flora

Definition

• Inflammation due to infection of lining of GI tract

Risk Factors

• Children
• Elderly
• Immunocompromised
• Recent antibiotics
• Food workers
• Schools/institutions/hospitals (outbreaks)
  Note: food poisoning is a notifiable disease in the UK

Populations Most at Risk of Developing Severe Disease

• Elderly
• Patients with multiple co-morbidities
• Immunocompromised (including patients taking steroids – 20mg of prednisolone/day is enough to be considered immunosuppressed)
• Long inpatient stay prior to developing symptoms (especially for CDI)

Organisms/causes

Bacterial

• Salmonella (epidemics, eg from poultry; typhi/paratyphi = 'typhoid/paratyphoid fever')
• Clostridium sp: - Difficile (recent antibiotics) - Botulinum (processed food; paralysis) - Perfringens (meat)
• Campylobacter (poultry; can precipitate Guillain Barre/Reiter's Syndromes)
• Staphylococcus aureus (meat)
• Bacillus cereus (rice)
• Vibrio parahaemolytica (raw seafood)/vibrio cholerae ('cholera')
• E Coli (eg O157, from meat/burgers; epidemics; can precipitate HUS/ARF etc)
• Shigella (any food)
• Cryptosporidium (HIV)

Viral

• Norovirus (hospital outbreaks; vomiting+; 'winter vomiting illness')

Protozoal

• Giardia, amoeba

Chemical toxins

• Mushrooms, garden flora

Symptoms

• Diarrhoea (can be bloody)
• Vomiting
• Abdominal pain
• Pyrexia
• PR bleeding
• Confusion – especially in the elderly

Key Questions

• "When did it start? How many times do bowels open in a 24 hour period?
• Is sleep disturbed by having to open bowels?
• Consistency of stool – is it like water? Passing blood?
• Current of recent antibiotic use?
• Any vomiting? – if yes, is it faeculent? – this is indicative of obstruction
• Any takeaways, eating out etc? Overseas travel?
• Contact with any unwell people? - especially if they have had diarrhoea
• What is your job? – very important if patient works in food handling (eg chef, waiter etc)
• Has it ever happened before (chronicity points away from an infective cause)?"

Signs

There may be little or nothing to find on clinical examination, but these must be looked for:

• Shock – tachycardia, hypotension, poorly perfused peripheries
• Pyrexia
• Abdominal tenderness, guarding and/or rebound. Peritonitis, if perforated
• Abdominal distention
• Blood, mass or hard stool on DRE
• Of severe sepsis/shock
  Note: DRE is mandatory

Investigation

Mild acute gastroenteritis does not necessarily need investigation; stool culture only, if relevant

Blood

• FBC; low Hb or low platelets, think ?DIC or ?Haemolytic-Uraemic Syndrome (eg O157 E Coli?), CRP
• U+E (hyper/hyponatraemia? hypokalaemia?), LFT, Bone, Glucose
• Blood culture – if pyrexial
• ABG - if signs of shock
• TFT  (if relevant)

Stool

• MC&S
• C.difficile testing
• Examination for ova, cysts and parasites – if history of overseas travel

Other

• ECG (AF? ie ischaemic colitis?)
• CXR (erect; perforation?)
• AXR (if abdominal distention present or obstruction suspected; toxic megacolon?)
• Flexible sigmoidoscopy if symptoms not resolving

Key Investigation

• Stool culture (+ CDI)

Specialist Investigations

• CT scanning and endoscopic investigations are sometimes needed. These decisions should be on a case-by-case basis
• CT scanning is indicated if colonic dilation/perforation are suspected
• Consider sigmoidoscopy, if microbiological stool analysis does not yield any abnormality, or inflammatory colitis is suspected

Differential Diagnoses

• Inflammatory colitis 
• Colo-rectal carcinoma
• Diverticular disease
• Ischaemic colitis (elderly, AF, arteriopath, very ill); operate immediately, if suspect diagnosis
• Overflow diarrhoea (elderly with constipation)
• Severe hyperthyriodism
  Note: do not forget 'complicated diarrhoea', including Haemolytic-Uraemic Syndrome (O157 E Coli) or causing DIC; or rare diseases like Carcinoid syndrome

Treatment

In CDI, if METRONIDAZOLE is used, 14 days of treatment is required

Treatment (first line)

Drugs

• Nil (supportive)
  Note: antibiotics only if unwell, immunosuppressed, frail elderly or certain organisms; resistance is common
• ± PO METRONIDAZOLE 800 mg stat, then 400 mg tds, for 14d (CDI)
• ± PO CIPROFLOXACIN 500 mg bd (salmonella)
• If possible, avoid antidiarrhoeals; esp in CDI (danger of toxic megacolon); if necessary PO loperamide 4mg od stat, then 2mg after each loose stool
• Give laxatives in overflow diarrhoea (common in elderly)

Procedures

• IV (+fluids, if dry)
  Note: if you are not giving iv fluids, why are you admitting them?; ie oral fluids at home may be appropriate
• Manage in sideroom
• If unwell, urinary catheter, and call ITU (CVP, arterial line)
• If ischaemic colitis, operate immediately

Important General Management Issues

• Thromboprophylaxis. Should be given to all patients unless contraindicated
• Stool chart. An accurate stool chart documenting frequency and consistency (Bristol stool chart) must be maintained, this is essential to assess patient improvement or deterioration
• Anti-diarrhoeal medication (eg loperamide) should not be given as will prolong infection and increase chance of colonic dilatation and hence perforation
• Anti-spasmodic medication (eg hyoscine butylbromide, buscopan) may cause an atonic colon will therefore predispose to colonic dilatation and increases the chance of colonic perforation
• Hand washing. It is best practice to wash hands with soap and water as alcohol sanitising gel in ineffective with some pathogens
• Side room. All patients with suspected infective diarrhoea must be admitted to a side room to minimize any chance of cross infection
• Notification of diseases. Some infective cases have to be notified to the Health Protection Agency. Contact tracing may be necessary
• Probiotics. Limited data to suggest that their use helps in diarrhoeal disease. No strong trial data to suggest this and their routine use is not recommended
• Patient review and pressure areas. These patients are commonly immobile for long periods. They must be on an appropriate mattress and have their pressure areas checked regularly
• These patients can be very unwell and septic. They need regular and appropriate clinical review (ie not just a quick look into the side room)
• Infection control teams are an essential part of the patient’s care team and their opinion should be actively sought

Key Management Decisions

• Antibiotics/not
• If CDI, steroids ± surgery/not

Stop

• Antibiotic, if cause
• Laxatives (a lot of elderly take these)

CDI Treatment (second line)

Drugs

• Moderate (3-5 motions/day; and WBC 10-15,000)
  • Oral Metronidazole 400mg 8 hourly for 14 days. If no response after 48 hours, change to oral Vancomycin 125mg 6-hourly for 14 days
• Severe, Level A (≥ 5 motions/day; and one of the following: dehydration, WBC >15,000, Temp > 38.5)
  • Oral Vancomycin 125mg 6-hourly for 14 days
• Severe, Level B (= A + hypotension, partial ileus, CT scan evidence of severe colitis)
  • Oral Vancomycin 500mg 6 hourly for 14 days plus IV Metronidazole 500mg 8 hourly
  • Also refer to Gastroenterologist and/or Surgeon today
• Severe, Level C (= A + complete ileus or toxic megacolon)
  • As for B. But Vancomycin to be given via a nasogastric tube or rectal installatio
  • Consider PO PREDNISOLONE 20-40 mg od/IV METHYLPREDNISOLONE 500 mg od
  • Do ABG (lactate?
  • Refer to Gastroenterologist and/or Surgeon urgently
  • Consider colectomy – best performed before serum lactate rises >5
• Relapses
• Use Vancomycin 125mg qds po, followed if necessary by pulsed doses of oral Vancomycin: following usual dose of 125mg 6 hourly for 10-14 days, it is given at 125mg 12 hourly for a week, 125mg once daily for a week and then 125mg every 2-3 days for 2 to 8 weeks in an attempt to restore normal colonic flora. Use the same antibiotic used to treat the initial episode

Prescribing Issues

• Antidiarrhoeals may increase chance of toxic megacolon in CDI

Admit?

• Usually (if case was mild, probably would not have come to hospital)

Bed plan

• Medical admission ward
• ± Gastroenterology, if not better in 48h, or suspect inflammatory colitis
• ± Gen surgery (ischaemic colitis, carcinoma, diverticular disease)
• ± ITU

Referrals

Medical

• Gastroenterology
• Microbiology
• ± Gen surgery
• ± ITU

Other

• Infection control nurse (esp if think food poisoning, CDI, or viral outbreak in hospital)

The Rest

Maxim

• "If you don't put your finger in it, you will put your foot in it"

Complications

• Bowel perforation

Follow-up

• None
• Though some diseases our notifiable:
• Cholera
• Dysentery (Shigella, Campylobacter, E Coli 0157, Salmonella, Balantidiasis, Entamoeba histolytica)
• Food poisoning (Toxins/infection)

Prognosis

• Prognosis is good in mild cases
• But mortality of CDI = 5-10%; 50% severe cases; 5% need surgery (operative mortality 30%)

Risk Stratification (who can be managed as outpatient)

• If not unwell, maintain oral fluids at home and the patient does not need admitting, or AB
• If moderately unwell, admit, but do not necessarily give AB

2° Prevention+ Health promotion

• Don't prescribe unecessary courses AB (especially in elderly); if you do, make courses short, then review efficacy of AB early
• Food hygiene
• Treatment of other family members in Giardia

Don't Forget

• Digital rectal examination (DRE) is mandatory
• Ischaemic colitis (especially in elderly in AF)
• Send stool off for CDI
• Chase stool culture for CDI, 24h later
• Report food poisoning (notifiable disease)
• Haemolytic-Uraemic Syndrome

Red Flags

• Toxic megacolon
• Severe sepsis/shock

References