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Y4 Gastrointestinal > GI tract infections - gastroenteritis > Flashcards

GI tract infections - gastroenteritis Flashcards

1
Q

Describe what gastroeneteritis is

A
  • It is an illness caused by eating food contaminated with micro-organisms (bacteria, viruses, parasites), toxins, poisons etc
  • They usually have GI symptoms (diarrhoea, abdominal pain, vomiting)
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2
Q

What is the main defining symptom of gastroenteritis ?

A

Diarrhoea (loose or watery stools, usually at least three times in 24 hours) is the main symptom of gastroenteritis.

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3
Q

Define what diarrhoea is

A

>3 unformed stools in 24hrs - exclude laxative use/abuse & other drugs / stimulants

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4
Q

Define what dysentry is

A
  • This is infection of the intestines resulting in severe diarrhoea with the presence of blood and mucus in the faeces. e.g. cause by Shigella, Campylobacter
  • It is generally associated with fever, abdominal pain, and rectal tenesmus (sense of incomplete defaecation).
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5
Q

What are the risk factors for developing a GI tract infection ?

A
  • Malnutrition (micronutrient) deficiency
  • Living in a closed/ semi-closed communities
  • Exposure to contaminated food/water /travel
  • Winter congregating/ summer floods
  • Age <5 , not breastfeeding or Older age > 65
  • Infection may arise from poorly cooked food, cooked food that has been left too long at room temperature or from uncooked food such as shellfish.
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6
Q

What can go wrong in the kitchen to cause gastroenteritis ?

A
  • cross contamination of raw & cooked food
  • preparation food too far in advance
  • inadequate heating & cooling
  • contaminated environment & equipment
  • poor personal hygiene
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7
Q

What 2 main are the characterisitic symptoms of a bacillus cerus GI infeciton ?

A
  • Sudden onset severe nausea and vomiting 1-6hrs - after eating rice due to preformed toxin (heat resistant spores)
  • Abdo cramps and watery diarrhoea may occur > 6hrs after (10-16) eating - after eating meat, stew, gravy, vanilla sauce due to diarrhoeal toxin
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8
Q

What is the microscopic appearance of bacillus cerus?

A

Gram pos bacilli

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9
Q

What are the characterisitic symptoms and causes of staphyloccocus aureus GI infeciton ?

A
  • Sudden onset severe nausea and vomiting - 1-6hrs after eating milk/meat/fish (e.g. potato salad, cream pastries etc)
  • Due to preformed toxin
  • May also have associated abdo pain, diarrhoea, fever
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10
Q

What are the characterisitc symptoms and causes of shigella

A
  • Bloody diarrhoea + Sudden fever
  • Abdo pain and vomiting
  • Symptoms occur 48-72hrs after infection and are caused by type 1 or 2 shiga toxin
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11
Q

What is the microscopic appearance of shigella ?

A

Gram neg bacilli

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12
Q

How is shigella spread?

A

Faecal-oral route:

  • Contaminated lakes/rivers (with stool)
  • Contact with somene with shigella - esp sexual MSM
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13
Q

Is shigella the only pathogen to produce shiga toxin ?

A

No - others such as E.coli may produce the toxin

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14
Q

Describe the microscopic appearance of E.coli

A

A facultative anaerobic, lactose-fermenting, Gram neg rod which is a normal gut commensal.

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15
Q

What are the 3 main serotypes of E.coli ?

A

O, K & H

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16
Q

What are the 2 main types of E.coli infecitons causing gastroenteritis ?

A

E.coli - most common cause of travellers diarrhoea

E.coli 0157 - bloody diarrhoea and potentially HUS

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17
Q

What toxin does E.coli 0157 produce ?

A

Verotoxin (VTEC)

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18
Q

What are the characterisitic presenting features of E.coli 0157 ?

A
  • Bloody diarrhoea & Abdo pain - tends to be more painful than other types of gastorenteritis. Usually occurs 1-3 days after infection but can be as late as 14 (1-14)
  • Also may have associated fever
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19
Q

What complication can develop from E.coli 0157 gastroenteritis?

A
  • Haemolytic uraemic syndrome (HUS)
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20
Q

What are the features of HUS and what features will be alongside it

A
  • A triad of AKI (oliguria and oedema), haemolytic anaemia and thrombocytopenia. - which presents as Abdo pain, fever, pallor, petechiae, oliguria
  • High WCC, Low platelets (thrombocytopenia), Low HB & Red cell fragments (haemolytic anaemia), LDH>1.5 x normal
  • 90% will have bloody diarrhoea from the gastroenteritis (but they may not have diarrhoea)
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21
Q

How soon after E.coli 0157 infection may HUS develop?

A

Within 2 weeks ==> diarrhoea may have stopped at this point

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22
Q

What specific subtype of E.coli 0157 is responsible for the majority of HUS cases ?

A

E.coli 0157:H7

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23
Q

What is the main source of E.coli 0157 infection ?

A
  • Typically undercooked beef (particularly beefburgers)
  • Also milk/water, person to person direct/indirect and animal contact (cattle) - suspect in people recently been to a farm
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24
Q

Who is most at risk of developing HUS with E.coli 0157 infection ?

A

Young people - majority of cases are in those < 16

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25
Q

What investigations need to be done in someone suspected of having E.coli 0157 gastroeneteritis ?

A
  • Send stool culture samples: all patients with bloody faeces
  • Send U&E, FBC, film, LFT, clotting, urine, (dipstick/micro), lactate dehydrogenase
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26
Q

What must all laboratory confirmed cases of E.coli 0157 be informed of to?

A
  • You must NOTIFY Health Protection Unit (HPU) of Haemolytic Ureamic Syndrome OR 0157 for Contact tracing & investigation
  • Environmental Health inspectors will inspect food premises etc
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27
Q

When else must you notify the health protection unit ?

A

if a case of any of the following is suspected:

  1. Cholera.
  2. Bloody diarrhoea presumed to be due to gastroenteritis. (basically E.coli 0157 presumed)
  3. Food poisoning (organisms that can be implicated in food poisoning include Campylobacter, Escherichia coli O157:H7, Salmonella, Shigella, Giardia, Yersinia enterolytica, Entamoeba histolytica, and norovirus).
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28
Q

What should not be given to patients with E.coli 0157 gastroenteritis ?

A
  • NO antibiotics: may precipitate HUS
  • NO anti-motility agents (anti-diarrhoeal)
  • NO NSAIDS
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29
Q

What is travellers diarrhoea ?

A

It is defined as at least 3 loose to watery stools in 24 hours with or without one of more of abdominal cramps, fever, nausea, vomiting or blood in the stool.

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30
Q

What is the most common cause of travellers diarrhoea ?

A

E.coli

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31
Q

What are the other potential causes of travellers diarrhoea ?

A
  • Campylobacter
  • Salmonella
  • Shigella
  • Viruses: norovirus and rotavirus (particularly if have been on cruise ships)
  • Parasites: these are less common causes. Giardia, cryptosporidium and Entamoeba histolytica
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32
Q

What are the typical features of travellers diarrhoea caused by E.coli?

A
  • Watery stools
  • Abdominal cramps and nausea
  • Common amongst travellers
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33
Q

What investigations should be done for someone with travellers diarrhoea ?

A
  • Stool culture
  • Stool wet prep on recently passed stool for amoebic trophozoites
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34
Q

What is the treatment of travellers diarrhoea ?

A
  • Supportive – fluid rehydration (oral/IV)
  • Bloody diarrhea with systemic upset may warrant treatment
  • In those travelling a fluoroquinolone (ciprofloxacin) or a macrolide (azithromycin) esp in asia due to resistance. Single dose can stop worsening
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35
Q

What is the main subtype of campylobacter causing gastroenteritis?

A

Campylobacter jejuni

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36
Q

What are characterisitc features and incubation period of campylobacter gastroenteritis ?

A
  • Fever - flu-like prodrome
  • Abdo pain - may have peritonism mimicing appendicitis
  • Bloody diarrhoea
  • Incubation period 16-48hrs
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37
Q

What is the main source of campylobacter gastroenteritis infections ?

A

Poultry & milk

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38
Q

What may be given to someone with campylobacter gastroenteritis if they have co-mobidities ?

A

A macrolide (but care as increasing resistance)

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39
Q

What complication may develop from campylobacter gastroenteritis ?

A

Guillian barre syndrome

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40
Q

What are the 2 main classifications of salmonella infection and state the infection type they cause ?

A

Based on serotyping:

  1. Non-typhodial - S.typhimurium & Enteriditis - cause gastroenteritis
  2. Tyhpodial - S.typhi & Paratyphi (types A, B & C) - cause enteric fever
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41
Q

What are the typical features of salmonella gastroenteritis infection

A
  • Diarrhoea +/- blood
  • Fever
  • Abdo pain
  • Vomiting

Incubation period = 12-48hrs days and caused by poultry, meat, raw egg

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42
Q

What does listeria monocytogenes infection typically cause

A

Only mild infection, causing flu-like symptoms or gastroenteritis.

43
Q

What are the typical features of listeria monocytogenes gastroenteritis ?

A
  • Fever, muscle aches, diarrhoea
  • Incubation period 9-48hrs
44
Q

What more serious complications can arise from listeria moncytogenes infection?

Also state who is at greater risk of these complications

A

Occasionally listeria infeciton can lead to septecaemia or meningitis 2-6 weeks after infection

Those at greatest risk are:

  • Immunosuppressed
  • Age> 50
  • Pregnant
45
Q

What can listeria monocytogenes infection in pregnant women cause ?

A

Misscarriage, still birth or severe illness to the unborn child

46
Q

What are the typical causes of listeria monocytogenes infection ?

A

Unpasteurised milk products, deli counter - soft cheeses, pate, cold meats etc

Recall pregnant women are to avoid these

47
Q

What is different about the investigation of listeria monocytogenes ?

A

Cannot use stool cultures are they are not sensitive.

Need to use cultures from a sterile source e.g. amniotic fluid, blood, urine and cerebrospinal fluid (CSF)

48
Q

What are the 2 main causes of viral gastroenteritis ?

A

Rotavirus & noravirus

49
Q

What are the clinical features of rotavirus gastroenteritis ?

A
  • Diarrhoea - mild watery to profuse. NO blood
  • Acute onset fever/malaise & Vomiting
  • Incubation period is 18-36 hrs
50
Q

Who is most at risk of rotavirus infection ?

A
  • Kids < 3y/o. Most have had it by 5
  • It is the commonest cause of D&V in children < 3
51
Q

During what time of the year is roatvirus infeciton most common ?

A

During the winter months

52
Q

How is rotavirus transmitted?

A

Person-person spread, direct or indirect (via Faecal-oral route)

53
Q

How is rotavirus infection diagnosed ?

A

PCR test on faeces

54
Q

What is the management of rotavirus infection ?

A

Supportive - Rehydration is key, orally where possible

55
Q

What is given to children and when to try to prevent rotavirus infection ?

A
  • Rotavirus vaccine - live attenuated
  • 2 doses, age 2 & 3 months
56
Q

Why must the rotavirus vaccine not be given to children older than 24 weeks ?

A

Because it increases the risk of intussusception

57
Q

What complication can develop post rotavirus infection ?

A
  1. Post infection malabsorption - which leads to more diarrhoea
  2. Repeat infections: milder each time
58
Q

How is noravirus transmitted ?

A

It is HIGHLY infectious transmitted by person to person (or on contaminated food/water) (via faecal-oral/droplet route)

59
Q

What are the clinical features of noravirus infection?

A
  • D&V explosive & sudden! (D more prevelent in adults and V more so in children)
  • Also fever, myalgia and sometimes headache
  • Incubation period 12-24hrs (think katie bennet shitting herself in bed)
60
Q

How is noravirus diagnosed ?

A

PCR on stool or PCR on vomit using red Copan viral swabs

61
Q

What is required to prevent spread of noravirus infection ?

A

Early ward closure/isolation/cohorting required

62
Q

What is the management of noravirus ?

A

Supportive - hydration is key

63
Q

How long is someone infectious with noravirus ?

A

48hrs after cessation of symptoms

64
Q

How long should someone stay off work after having infectious diarrhoea ?

A

Stay off until 48hrs post cessation of symptoms

65
Q

Give the 2 main non-infectious diarrhoea ?

A

E.coli 0157 and campylobacter

66
Q

Is a stool sample required for all cases of gastroenteritis ?

A

No - usually not necessary for most adults who present with acute, watery diarrhoea

67
Q

When should you send a stool sample in someone presenting with diarrhoea?

A
  • The person is systemically unwell.
  • There is blood or pus in the stool.
  • The person is immunocompromised.
  • There is a history of recent hospitalization and/or antibiotic treatment.
  • Diarrhoea occurs after foreign travel to anywhere other than Western Europe, North America, Australia, or New Zealand.
  • Diarrhoea is persistent and giardiasis is suspected.
  • There is uncertainty about the diagnosis of gastroenteritis.
68
Q

What tests does a stool sample undergo ?

A

Microscopy & culture/sensitivities

69
Q

What should be done to assess someone with gastroenteritis (besides diagnostic investigations)

A
  • Assess for features of dehydration and vital signs
  • Review medications
  • Investigate for potential causes (Recent contact with someone with acute diarrhoea and/or vomiting, Exposure to a known source of enteric infection (possibly contaminated water or food), Recent travel abroad, Recent antibiotics or hospital admission within the last 8 weeks — suspect infection with Clostridium difficile, Use of drugs such as PPI’s and metformin.)
70
Q

What is the treatment of acute gastroenteritis (acute means < 14 days) ?

A

Supportive - no antibiotics

71
Q

When may oral rehydration solution (ORS) be needed to treat dehydration in patients with gastroenteritis ?

A

The frail or very elderly

72
Q

Are anti-diarrhoeals usually needed for treatment of gastroenteritis ?

A
  • No - However, they may be useful for symptomatic control in adults with mild-to-moderate diarrhoea
  • 1st line = Loperamide
73
Q

When are anti-diarrhoeal agents contraindicated in gastroenteritis ?

A
  • Blood and/or mucus in the stools, or high fever (indicating dysentery) - so in most exam question cases lol (refer to table)
  • Confirmed, probable, or suspected vero cytotoxin-producing Escherichia coli 0157 (VTEC) infection.
  • Shigellosis.
74
Q

What measures are taken to control the spread of diarrhoea infection in hospital ?

A
  • All patients with diarrhoea that might be infectious should be placed in a single room with own toilet/commode
  • Cohort nursing may be required - all patients with the same infection nursed together with their own team of nurses
  • Wards may be closed to new admissions
  • Increased ward cleaning/disinfection
  • Hand washing rather than alcohol gel, particularly for patient with C diff (spores survive hand gel)
  • Gloves & Apron/gown if contamination anticipated
  • Single use items of equipment where possible
  • Cleaning/disinfection of items with hypochlorite, terminal disinfection of room
75
Q

What are the causes of enteric fever typhoid/paratyphoid) ?

A

Salmonella typhi and Salmonella paratyphi (types A, B & C) respectively.

76
Q

Who is enteric fever most common in ?

A

Those returning from Indian subcontinent and SE Asia

77
Q

What is the microscopic appearance of the causes of enteric fever ?

A

aerobic, Gram-negative rods (because the are subclasses of salmonella)

78
Q

What are the typical features of enteric fever ?

A

Fever & arthraligia

Non-specific:

  • Headache
  • Constipation or diarrhoea (usually after 1st week)
  • Dry cough
  • Bradycardia

Rose spots on trunk

79
Q

What is the incubation period of enteric fever ?

A

7-18 days

80
Q

What complications can people with enteric fever develop ?

A
  • osteomyelitis (especially in sickle cell disease where Salmonella is one of the most common pathogens)
  • GI bleed/perforation
  • meningitis
  • cholecystitis
  • chronic carriage
81
Q

How is enteric fever diagnosed ?

A
  • Blood culture is the mainstay
  • Alternativley Urine or stool cultures may be done
82
Q

What is the treatment of enteric fever ?

A
  • Isolate patient & ensure hygeine standards
  • Fluid replacement
  • Treatment empirically if patient is unstable (has severe sepsis) with IV Ceftriaxone
  • Otherwise give ciprofloxacin, or azithromycin or ceftriaxone
83
Q

Go over the causes of fever & jaundice:

Pre-hepatic (haemolytic):

  • Malaria
  • HUS as complication of diarrhoeal illness – E.coli 0157, Shigella
  • Sickle cell crisis triggered by infection

Hepatic:

  • Hepatitis A and E – acute (occasionally Hepatitis B)
  • Leptospirosis – Weils diseases (Icteric, haemorrhagic and renal failure)
  • Malaria
  • Enteric fever
  • Rickettsia (scrub typhus, Rocky Mountain spotted fever etc)
  • Viral haemorrhagic fever

Post-hepatic:

  • ascending cholangitis and helminths
A
84
Q

What is the cause of amoebiasis infection ?

A

Entamoeba histolytica (an amoeboid protozoan) and spread by the faecal-oral route and associated with poor sanitation

85
Q

What are the 2 types of amoebiasis infection ?

A
  1. Infection can be asymptomatic carriage
  2. OR cause amoebic dysentery.
86
Q

What are the clinical features of ameobic dysentry ?

A
  • Gradual onset Profuse Bloody diarrhoea / colitis (can perforate)
  • Abdominal pain which may last several weeks
  • Fever
  • Toxic and unwell, abdominal tenderness, peritonism
87
Q

How is ameobic dysentery infection diagnosed ?

A
  • 1st = Stool microscopy for trophozoites or cysts (distinguish between E. histolytica and E. dispar)
  • AXR to exlcude - toxic megacolon
  • 2nd = Endoscopy for biopsy (not if evidence of toxic dilatation)
88
Q

What is the treatment of ameobic dysentery ?

A

metronidazole

89
Q

What complications can develop from amoebiasis ?

A

liver and colonic abscesses.

90
Q

What are the clinical features suggestive of a ameobic liver abscess ?

A

Subacute presentation over 2-4 weeks:

  • High swinging fever, sweats
  • Upper abdominal pain
  • Sometimes history of GI upset (dysentery)
  • Hepatomegaly
  • Point tenderness over right lower ribs
91
Q

What investigations should be done in someone with a ameobic liver abscess ?

A
  • Abnormal LFTs
  • CXR – raised right hemi-diaphragm
  • USS/CT scan
  • Serology
  • Stool microscopy - often negative

Those are the expected results of diff investigations, to diagnose do PCR and ultrasound/CT +/- aspiration

92
Q

What is the treatment of an ameobic liver abscess ?

A
  • Give metronidazole or tinidazole for the abscess
  • Need to also clear the gut lumen of parasites - give Paramomycin/diloxanide
93
Q

What is the cause of giardia ?

A
  • Giardia intestinalis (lamblia) a flagellated protozoa
  • Spread by the faecal-oral route and Invades the duodenum and proximal jejunum
94
Q

What is the incubation period of gairdiasis ?

A

7 days

95
Q

What are the clinical features suggestive of giardiasis ?

A
  • Watery, malodorous diarrhoea (non-bloody)
  • Causes fat malabsorption so stools may seem greesy or float
  • Bloating, flatulence
  • Abdominal cramps
  • Weight loss
96
Q

What are the risk factors for giardiasis ?

A

Travel to areas where the water supply may be contaminated, swimming in ponds etc

97
Q

How is giardiasis diagnosed ?

A
  • 1st line = PCR of stool
  • 2nd line = OGD for dudoenal biopsy (rarley necessary)
98
Q

What is the treatment of giardiasis ?

A

Metronidazole or tinidazole

99
Q

What is the cause of cholera

A

Vibro cholerae - Gram negative bacteria

100
Q

What are the typical features of cholera ?

A
  • profuse ‘rice water’ diarrhoea
  • dehydration
  • hypoglycaemia
  • Associated with outbreaks e.g. in refugee camps
101
Q

What is the incubation period of cholera ?

A

Few hrs to 5 days

102
Q

How is cholera diagnosed ?

A

Stool microscopy & culture

103
Q

What is the treatment of cholera ?

A
  • oral rehydration therapy
  • antibiotics: doxycycline, ciprofloxacin
104
Q

If someone presents with high-output stoma confirmed to be non-infectious what is the typical meds you can give them?

A

Loperamide upto a max of 64mg in 24hrs + codeine + omeprazole.

Y4 Gastrointestinal (28 decks)

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