Viral gastroenteritis (I) Flashcards

1
Q

Define viral gastroenteritis.

A

Acute inflammation of the lining of the stomach and intestines caused by enteropathogenic viruses

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2
Q

What is the typical presentation of viral gastroenteritis?

A

Increased frequency of defecation lasting <14 days, which may be accompanied by nausea, vomiting, anorexia, abdominal cramps and fever

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3
Q

What causative viruses are there for viral gastroenteritis? (3)

A

Norovirus > sapovirus > rotavirus (most common in infants and children)

(Hepatitis A&E, caliciviruses, astroviruses, adenoviruses, parvoviruses)

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4
Q

What are some bacterial causes of gastroenteritis? (3)

A
  • Campylobacter
  • E. coli
  • salmonella
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5
Q

What are some subtypes of E. coli in relation to gastroenteritis? (5)

A
  • enterohaemorrhagic (EHEC): Shiga-toxin producing, O157 serogroup
  • enterotoxic (ETEC): cholera-like toxin
  • enteroinvasive (EIEC): shigella-like illness
  • enteroaggregative (EAEC)
  • enteropathogenic (EPEC)
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6
Q

Describe the incubation period for different pathogens for viral gastroenteritis.

A
  • hours: preformed toxins (S. aureus) and non-infectious toxins (salmonella)
  • days: most viruses (exc. Hep A&E), Campylobacter, Shigella, parasites
  • weeks: Hep A&E, chronic exposure to heavy metals
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7
Q

What type of transmission is responsible for most cases of viral gastroenteritis?

A

Person-to-person transmission is responsible for infection in most sporadic cases

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8
Q

What is viral gastroenteritis mainly caused by?

A

Norovirus

However, most common cause of food poisoning in UK is Campylobacter jejuni (will present after a summer BBQ/in clusters)

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9
Q

What are the key clinical features of viral gastroenteritis?

A
  • diarrhoea (sudden onset)
    • blood/mucus in stool - indicates invasion of intestinal/colonic mucosa
  • vomiting
  • nausea
  • abdominal pain
  • fever and malaise
  • loss of appetite
  • signs of dehydration (dry mucous membranes, skin turgor, capillary refill, reduced urine output, tachycardia, hypotension, weight loss)
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10
Q

Describe different types of stool and their causative organisms in viral gastroenteritis.

A
  • blood/mucus in stool - indicates invasion of intestinal/colonic mucosa
  • blood more common in Shiga-toxin-producing E. coli/Campylobacter/Shigella/amoebic
  • rice-water stool - cholera
  • watery stool - enterotoxigenic E. coli
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11
Q

What are the signs of dehydration in viral gastroenteritis? (7)

A
  • dry mucous membranes
  • skin turgor
  • capillary refill
  • reduced urine output
  • tachycardia
  • hypotension
  • weight loss
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12
Q

When do symptoms set in for viral gastroenteritis caused by norovirus?

A

Abrupt onset, usually short-lived GI upset 24-48h after inoculation

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13
Q

What complication can viral gastroenteritis caused by norovirus cause and in which group?

A

Usually self-limiting in healthy people but can cause pre-renal AKI in frail population

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14
Q

How can we prevent viral gastroenteritis caused by norovirus?

A

Strict handwashing with soap and warm water to prevent spread

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15
Q

What can be seen on examination of viral gastroenteritis? (3 + 1)

A
  • fever
  • skin changes
  • bloating, tenderness

Significant tenderness to palpation, guarding, rebound or point-specific tenderness should lead the clinician to consider other causes of symptomatology

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16
Q

What are some risk factors for viral gastroenteritis?

A
  • exposure to contaminated food
  • close contact with infected people
  • poor hygiene
  • extremes of age
  • immunocompromised
  • recent Hx of travel
  • consumption of: undercooked meat, raw seafood, unpasteurised milk/juice, raw eggs
17
Q

How is viral gastroenteritis diagnosed?

A

Clinical diagnosis based on Hx and examination; tests rarely needed to diagnose the pathogen

18
Q

What are the 1st line investigations for viral gastroenteritis if we are starting IV fluids? (3)

A
  • FBC - look for abnormally high/low WBC, Hb or platelets
  • U&Es - urea, creatinine or ratio may be elevated –> because any diarrhoeal condition can lead to dehydration so important to monitor; IV rehydration may need to be tailored
  • creatinine - abnormal result may indicate AKI
19
Q

What investigation do we order for viral gastroenteritis if symptoms are atypical and you suspect a bacterial or parasitic aetiology?

A

Stool for culture, ova and parasites when there is:

  • persistent diarrhoea (>14 days)
  • blood/pus in stool
  • tenesmus
  • severe abdominal pain
  • suspicion of non-viral gastroenteritis
  • Hx of hospitalisation or Abx therapy in last 6 months
  • Hx of recent foreign travel
20
Q

What investigation is used to identify the causative virus for viral gastroenteritis?

A

Stool viral culture (rarely necessary)

21
Q

What are some differential diagnoses for viral gastroenteritis?

A
  • food poisoning (multiple people after eating same food/drink)
  • C. difficile colitis (recent Abx use)
  • non-infectious diarrhoea (caused by toxins/Abx side effects/post-infectious IB)
  • IBD
  • food allergies
  • IBS
  • microscopic colitis
  • acute appendicitis / cholecystitis / pancreatitis / hepatitis
  • malabsorption syndromes
  • small/large bowel obstruction
  • diverticulitis
  • systemic vasculitis
22
Q

How can you distinguish between bacterial and viral gastroenteritis?

A
  • viral infection generally produces diarrhoea without blood or mucus + watery diarrhoea is a prominent symptom
  • viral - fevers, headaches, arthralgia, cramps (more generalised and benign symptoms)
  • bacterial - tenesmus
23
Q

What is the first-line treatment for viral gastroenteritis with mild to moderate dehydration?

A
  • oral rehydration & fluids
    • replace fluid and electrolytes lost through diarrhoea by solutions containing Na+, K+ and glucose
    • use a reduced osmolarity oral rehydration solution (50-60mmol/L) over 3-4 hours
  • CONSIDER anti-emetic (only if intractable vomiting and unable to tolerate oral fluids) –> ondansetron or cyclizine
  • CONSIDER antidiarrhoeal (avoid in those with bloody diarrhoea or inflammatory cause) –> loperamide
24
Q

What is the first-line treatment for viral gastroenteritis with severe dehydration or unable to tolerate oral fluids?

A
  • IV fluids
  • CONSIDER anti-emetics (ondansetron or cyclizine)
  • CONSIDER antidiarrhoeal (loperamide)
25
Q

What are some indicators that a patient with viral gastroenteritis may need urgent fluid resuscitation? (5)

A
  • systolic BP<100mmHg
  • heart rate >90bpm
  • cold peripheries
  • respiratory rate >20
  • NEWS >5
26
Q

For which patients with viral gastroenteritis do you withhold antihypertensives and/or diuretics if hypotensive?

A
  • coronary heart disease
  • heart failure
  • stroke
  • CKD
27
Q

When do you NOT use anti-peristaltic agents (codeine phosphate) in viral gastroenteritis?

A

Do NOT use in fever / systemic toxicity / bloody diarrhoea

28
Q

What do we do if a patient with viral gastroenteritis has systemic signs?

A

Admit + IV fluids + stool culture

29
Q

How do we manage C. diff (gram +ve rod) gastroenteritis?

A

Oral vancomycin (add IV metronidazole if severe)

30
Q

How do we manage salmonella and shigella gastroenteritis?

A

Ciprofloxacin

31
Q

How do we manage Campylobacter gastroenteritis?

A

Macrolide e.g. erythromycin

32
Q

How do we manage cholera gastroenteritis?

A

Tetracycline

33
Q

When are antibiotics advised for gastroenteritis?

A

If patient is systemically unwell, immunosuppressed, elderly
Or if >3 days

34
Q

What are some complications of viral gastroenteritis?

A
  • electrolyte abnormalities - metabolic acidosis
  • acute renal failure
  • transient lactose intolerance
  • Guillian-Barre syndrome (acute autoimmune demyelinating polyneuropathy affecting PNS, in 30% of cases after Campylobacter jejuni gastroenteritis)
    • back/leg pain in initial stages
    • ascending weakness, paraesthesia and pain
    • areflexia
    • can affect respiratory muscles –> failure and death
    • CSF = high protein, normal WCC; nerve conduction studies
    • treat with IV immunoglobulins and plasmapheresis
35
Q

Describe the prognosis of viral gastroenteritis.

A

Excellent for most, but if volume depletion and electrolyte disturbances are not recognised and managed properly –> serious morbidity and mortality