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Yr 2 - Clinical Pathology > GI Infections II > Flashcards

GI Infections II Flashcards

1
Q

What is the leading cause of malnutrition in children under 5?

A

Diarrhoea

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2
Q

What physical factors can reduce incidence of GI infections?

A

food and water hygiene, handwashing, animal contact

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3
Q

What host factors can reduce incidence of GI infections?

A

healthy microbiome, stomach acid barrier, local immune responses

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4
Q

What interventions can reduce incidence of GI infections?

A

vaccines, antimicrobial treatments, rehydration therapies

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5
Q

Which organism is the most common cause of bacterial gastroenteritis in England?

A

Campylobacter

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6
Q

How is Campylobacter most commonly acquired?

A

Undercooked meat

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7
Q

Common causes of GI infections:

A
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8
Q

Intoxication vs infection?

A
  • Infection: occurs when live bacterial cells/viruses/parasites are ingested which grow in the digestive tract and cause symptoms e.g. Salmonella infection.
  • Intoxication: ingestion of pre-formed toxin
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9
Q

Incubation period of intoxication vs infection?

A

Intoxication –> rapid incubation period (minutes to hours)

Infection –> slower incubation period (hours to days)

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10
Q

Symptoms of intoxication vs infection?

A

Intoxication –> vomiting, nausea, diarrhoea, weakness, resp. failure, numbness, sensory/motor dysfunction

Infection –> diarrhoea, nausea, vomiting, abdo cramps, fever

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11
Q

Onward transmission of intoxication vs infection?

A

Intoxication –> not communicable

Infection –> person to person (faecal oral)

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12
Q

Factors causing intoxication vs infection?

A

Intoxication - inadequate cooking, improper handling temperatures

Infection - inadequate cooking, cross contamination, poor hygiene and handwashing procedures

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13
Q

Which organisms are the cause of foodborne gastroenteritis from;

a) dairy
b) eggs
c) meats
d) poultry?

A

a) Campylobacter, Salmonella species
b) Salmonella sp
c) Clostridium perfringens, Bacillus cereus, Aeromonas, Campylobacter, Salmonella sp, E coli
d) Campylobacter sp.

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14
Q

Does S. aureus cause food poisoning via intoxication or infection?

A

Intoxication - produces heat stable enterotoxin

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15
Q

Symptoms of S. aureus food poisoning?

A

N&V (can be projectile), no diarrhoea

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16
Q

Ibcubation time of S. aureus food poisoning??

A

1-4 hours after eating

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17
Q

Common foods causing S. aureus food poisoning?

A

Mayonnaise, meat, dairy

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18
Q

Does Bacillus cerus cause food poisoning via infection or intoxication?

A

Intoxication

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19
Q

What are the 2 types of GI illness that Bacillus cereus can cause? Which toxin causes each type?

A
  1. emetic (vomiting) syndrome –> heat stable emetic toxin
  2. diarrhoeal syndrome –> heat labile toxin
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20
Q

What is a heat stable toxin?

A

survives the cooking process

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21
Q

What is a heat labile toxin?

A

can be changed or destroyed at high temperatures

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22
Q

Symptoms of the 2 types of Bacillus cereus food poisoning?

A
  • Vomiting syndrome (heat stable) - Vomiting but no diarrhoea
  • Diarrhoea syndrome (heat labile) - Little vomiting but profuse diarrhoea
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23
Q

Incubation periods of the 2 types of Bacillus cereus food poisoning?

A

Heat stable emetic toxin –> 1-4 hours after eating

Heat labile toxin –> 12-14 hours after eating

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24
Q

Food source of the 2 types of Bacillus cereus food poisoning?

A

Heat stable emetic toxin –> cooked rice and other starchy foods

HEat labile toxin –> wide variety of foods

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25
Q

Which bacteria causes food poisoning from cooked rice?

A

Bacillus cereus

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26
Q

Does Clostridium perfringens cause food poisoning via intoxication or infection?

A

Intoxication –> heat labile toxin

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27
Q

Symptoms of food poisoning caused by Clostridium perfringens?

A

Abdominal cramps, watery diarrhoea

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28
Q

Incubation period of food poisoning caused by Clostridium perfringens?

A

1-4 hours after eating

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29
Q

What are the advantages of spore-forming bacteria?

A

Bacterial spores offer the advantage of a higher survival rate during the acidic stomach passage and better stability during the processing and storage of the food product.

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30
Q

Food source of food poisoning caused by Clostridium perfringens?

A

Meat, meat products

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31
Q

Does Clostridium botulinum cause poisoning via intoxication or infection?

A

Intoxication –> is a neurotoxin

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32
Q

Symptoms of Clostridium botulinum food poisoning?

A
  • Blurred vision
  • Respiratory failure
  • Flaccid paralysis
  • Neurological symptoms
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33
Q

Food source of Clostridium botulinum food poisoning?

A
  • Improperly canned food
  • Honey
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34
Q

What is infant botulism?

A

C. Botulinum spores in honey can colonise infant (<1yr) GI tract and produce toxin

  • Constipation
  • Neurological symptoms
  • Milder disease than adults
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35
Q

Does Salmonella cause food poisoning via infection or intoxication?

A

Infection

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36
Q

Most common type of Salmonella?

A

S. enteritidis

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37
Q

Symptoms of Salmonella food poisoning?

A

Cramps, diarrhoea, fever, myalgia, nausea and vomiting

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38
Q

Food source of Salmonella food poisoning?

A

Poultry, birds and some reptiles

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39
Q

Why are high numbers of Salmonella needed to cause infection?

A

As killed by gastric acid

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40
Q

Incubation period of Salmonella food poisoning?

A

6-8 hours after eating

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41
Q

When should antibiotic treatment be considered for Salmonella infection?

A
  • Are older than 50 years of age.
  • Are immunocompromised.
  • Have cardiac valve disease or endovascular abnormalities, including prosthetic vascular grafts.

Antibiotic treatment is not recommended for healthy people with gastroenteritis due to Salmonella infection.

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42
Q

What is the antibiotic treatment for Salmonella infection?

A

Ciprofloxacin (500mg twice a day for 1 day only)

43
Q

Does Shigella sp. cause disease via infection or intoxication?

A

Infection

BUT some produce an enterotoxin and a Shiga toxin

44
Q

What is Bacillary dysentery? What is it caused by?

A

A type of dysentery and a severe form of shigellosis (the term is usually restricted to Shigella infections)

45
Q

What are the 3 types of Shigella sp.?

A
  1. S. dysenteriae –> most severe
  2. S. flexneri
  3. S. sonnei –> most mild (tend to see in UK)
46
Q

Why are only low numbers of Shigella needed to cause infection?

A

Fairly resistant to killing by gastric acid

47
Q

Symptoms of bacillary dysentery?

A
  • Waterdy, bloody, mucoid stool
  • Abdominal pain
  • Fluid and electrolyte loss
48
Q

Incubation of bacillary dysentery?

A

36-72 hours

49
Q

Transmission of bacillary dysentery?

A

Found in the guts of humans, primates

Transmission via faecal oral route

50
Q

When should antibiotic treatment for gastroenteritis caused by Shigella be considered?

A
  • With severe disease.
  • Who are immunocompromised.
  • With bloody diarrhoea.

Antibiotic treatment is not recommended for healthy people with mild shigellosis.

51
Q

What is the antibiotic treatment for gastroenteritis caused by Shigella?

A

Ciprofloxacin 500 mg twice a day for 1 day only (continued for 5 days if the organism is Shigella dysenteriae)

52
Q

Most common symptom of Campylobacter infection?

A

Watery diarrhoea (also get nausea, vomiting, malaise and headache)

53
Q

Does Campylobacter cause food poisoning via infection or intoxication?

A

Infection

54
Q

Incubation period of Campylobacter infection?

A

2-5 days

55
Q

Source and transmission of Campylobacter infection?

A

Poultry, birds

Faeco-oral route

56
Q

When should antibiotics be considered for Campylobacter infection?

A
  • With severe symptoms (high fever, bloody diarrhoea, or more than eight stools per day).
  • Who are immunocompromised.
  • Whose symptoms appear to be worsening.
  • Whose symptoms have lasted longer than 1 week.

Antibiotic treatment is not usually necessary for people with mild symptoms.

Fluid and electrolyte replacement may be needed.

57
Q

What is the antibiotic treatment for Campylobacter infection?

A
  • Erythromycin (alternative: clarithromycin or azithromycin)
  • Ciprofloxacin is an alternative to macrolides
58
Q

Does E. coli 0157 cause disease via intoxication or infection?

A

Infection BUT can produce Shiga toxin

59
Q

Symptoms of E. coli 0157 infection?

A
  • Watery then blood diarrhoea
  • Haemorrhagic colitis (10% develop Haemolytic Uraemic Syndrome)
60
Q

Incubation period of E. coli 0157 infection?

A

2-5 days

61
Q

Food source of E. coli 0157 infection?

A

Cattle and meat

62
Q

What is haemolyic uraemic syndrome? Which organism is it caused by?

A
  • E. coli 0157
  • Results in acute renal failure, thrombocytopaenia, microangiopathic haemolytic anaemia
63
Q

Treatment for gastroenteritis due to Vero cytotoxin-producing Escherichia coli 0157 (VTEC)?

A
  • Management is entirely supportive; there is no specific treatment
  • Do not prescribe antibiotics
  • Avoid antimotility drugs, such as loperamide or diphenoxylate, and opioids
  • Advise against the use of nonsteroidal anti-inflammatory drugs, such as ibuprofen (due to effect on kidneys)
64
Q

Summary of other gastrointestinal E. coli infections

A
65
Q

What are the 5 major organisms causing viral gastroenteritis?

A
  1. Rotavirus
  2. Adenovirus
  3. Norovirus
  4. Astrovirus
  5. Calicivirus
66
Q

Summary of viral gastroenteritis;

A
67
Q

Is there a rotavirus vaccine?

A

Yes

68
Q

What is amoebic dysentry?

A

An infection caused by any of the amoebae of the Entamoeba genus.

PARASITIC

69
Q

90% of amoebic dysentery cases are asymptomatic. When are symptoms most common?

A

during infection by Entamoeba histolytica

70
Q

Symptoms of amoebic dysentery caused by Entamoeba histolytica?

A
  • Watery then bloody diarrhoea
  • Nausea
  • Vomiting
  • Tenesmus
  • Malaise

Exrta-intestinal symptoms:

  • Liver abscess – high fever and abdominal pain
71
Q

Incubation period of Entamoeba histolytica?

A

15 days

72
Q

Food source of Entamoeba histolytica?

A

Contaminated food or water

73
Q

Treatment for amoebic dysentery?

A

Prescribe treatment for all people with confirmed amoebic dysentery (or asymptomatic amoebiasis):

  • Acute invasive amoebic dysentery or liver abscess –> metronidazole or tinidazole followed by 10 day course of diloxanide furoates the drug of choice for treating giardiasis.
  • Asymptomatic patients with cysts in faeces –> diloxanide furoate
74
Q

What is cryptosporidiosis? Which organism causes it?

A

A highly contagious intestinal infection from exposure to Cryptosporidium parvum (which live in the intestines of humans and other animals and are shed through the stool).

75
Q

Symptoms of cryptosporidiosis?

A
  • Watery diarrhoea, weight loss, low grade fever
  • Can be asymptomatic carrier
  • Severe chronic diarrhoea in immunocompromised
76
Q

Incubation period of cryptosporidiosis?

A

2-10 days

77
Q

Food source of cryptosporidiosis?

A

Found in animals, fish, reptiles, common water contaminant

78
Q

Treatment of cryptosporidiosis?

A
  • Usually self limiting, therefore no treatment required
  • No antibiotic treatment is necessary in immunocompetent individuals

For immunocompromised:

  • Treat the underlying condition (eg HAART for HIV)
  • All drugs available in the UK are of unproven benefit (paromomycin, azithromycin, clarithromycin)
  • Nitazoxanide available on a named patient basis, but of unproven benefit
79
Q

What is giardiasis? Which organism causes it?

A

Giardiasis is an infection in your small intestine caused by a parasite called Giardia intestinalis

80
Q

What is the most common protozoan parasite of humans?

A

Giardia intestinalis

81
Q

Symptoms of Giardiasis?

A
  • Foul smelling, watery diarrhoea, cramps
  • Steatorrhoea, flatulence
  • Chronic relapsing diarrhoea in some
82
Q

Incubation period of giardiasis?

A

1-4 weeks but sudden onset

83
Q

Source of Giardia intestinalis?

A

common water contaminant

84
Q

Treatment of giardia intestinalis?

A

Prescribe treatment for all people with confirmed giardiasis:

  • Metronidazole is drug of choice
  • Tinidazole is an alternative to metronidazole
85
Q

Organism behind cholera?

A

Vibrio cholerae (bacteria)

86
Q

Symptoms of cholera?

A
  • Abrupt, water “rice water stool
  • Significant fluid loss, hypervolemic shock
  • Cholera toxin leads to fluid loss
87
Q

Source of vibrio cholerae?

A

Water or food borne (esp shellfish)

88
Q

Treatment of cholera?

A
  • Basis of treatment is replacement of lost fluids
  • Oral rehydration if not severe (80% of people treated successfully this way)
  • Anitbiotics recommended for patients with moderate to severe dehydration (tetracycline, doxycycline, ciprofloxacin)
89
Q

What is enteric fever? Which organism causes it?

A
  • Also known as typhoid fever, is a common infectious disease in low and middle income countries. It is the commonest bacterial cause of fever in returning travellers and migrants from these areas.
  • Caused by Salmonella typhi, Salmonella paratyphi –> engulfed by macrophages and migrate to liver, spleen and bone marrow
90
Q

Symptoms of enteric fevers?

A
  • Stage 1: fever, headache, Malaise, anorexia, constupation/diarrhoea
  • Stage 2: diarrhoea, splenomegaly, high fever, rose spots
  • 1-5% become chronic carriers
91
Q

Treatment of enteric fever?

A

Prescribe immediate antibiotic treatment for all people with confirmed enteric fever.

–Azithromycin (5 days) is the drug of choice for treating Enteric

–Multiple resistant – fluoroquinolone (5 days) or cefixime (7-14d)

–Quinlone resistant – azithromycin (7d) or ceftriaxone (10-14d).

Antimicrobial sensitivities important to guide treatment

92
Q

How common is antibiotic associated diarrhoea?

A

Develops in ~30% patients on antibiotics

93
Q

What is the most common organism causing antibiotic associated diarrhoea?

A

C. difficile

94
Q

How do antibiotics lead to diarrhoea?

A
  • Antibiotics deplete normal gut flora
  • C. difficile produces toxins
95
Q

Symptoms of C. difficile infection?

A
  • Foul smelling, watery diarrhoea, cramps, low grade fever
  • Can lead to PMS, toxic megacolon, death
  • Toxin mediated inflammation, Spores aid transmission
  • Recurrence in 30%
96
Q

Risk factors for C. difficile infection?

A

antibiotics, age >65yrs, hospital stay

97
Q

What is Pseudomembranous colitis?

A

Pseudomembranous colitis refers to swelling or inflammation of the large intestine due to an overgrowth of Clostridioides difficile (C difficile) bacteria. This infection is a common cause of diarrhea after antibiotic use.

98
Q

Treamtnet of antibiotic associated diarrhoea?

A

STOP predisposing antibiotic and start treatment with vancomycin, or fidaxomicin (metronidazole can be used, but only recommended in certain scenarios)

Other treatments include immunoglobulin, bezlotoxumab and faecal transplants

99
Q

What is streptococcus gallolyticus associated with?

A

Infective endocarditis and septicaemia in elderly

BUT

Also strongly associated with colorectal cancer (not a cause, but may have a role in promoting colorectal cancer)

100
Q

What should you always investigate patients with S. gallolyticus for?

A

Colo-rectal cancer

101
Q

What is gastrointestinal tuberculosis?

A

GI infection caused by Mycobacterium tuberculosis

102
Q

Symptoms of gastrointestinal tuberculosis?

A
  • Abdominal pain
  • Weight loss
  • Anaemia
  • tiredness
  • Night sweats
103
Q

What can gastrointestinal tuberculosis be confused with?

A

IBD, intestinal infections, malignancy

104
Q

Treatment of GI TB?

A

Treatment of TB requires prolonged therapy with multiple agents to combat resistance development

For people with active TB without CNS involvement, offer:

  • isoniazid (with pyridoxine), rifampicin, pyrazinamide and ethambutol for 2 months, then
  • isoniazid (with pyridoxine) and rifampicin for a further 4 months.

Modify the treatment regimen according to drug susceptibility testing

Yr 2 - Clinical Pathology (80 decks)

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