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S3: Gastrointestinal > 9a.) GI Infections > Flashcards

9a.) GI Infections Flashcards

1
Q

Define, and describe difference between, microbiome and microbiota

A
  • Microbiome: refers to all genomes in gut environment
  • Microbioata: refers to all organisms within gut
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2
Q

State 5 functions of the gut microbiota

A
  • Pathogen inhibition: act as competitors against pathogenic organisms e.g. for nutrients
  • Immune protection: microbiota interact with gut lymphoid tissue; if gut senses microorganisms that shouldn’t be there immune response will occur
  • Nutrient metabolism
  • Drug metabolism
  • Gut brain axis: thought that gut microbiota has role depression, anxiety etc…
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3
Q

Why can antibiotics lead to a infection?

A

Antibiotics can decrease gut microbiota which usually inhibit pathogens in gut

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4
Q
A
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5
Q

Describe how someone may present if they have a GI infection

A
  • Diarrhoea
  • Mucus/blood in stool
  • Nausea
  • Vomitting
  • Pain
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6
Q

If someone presents with GI infection, what questions must you ask about their past medical history?

A
  • Immunocompromised state
  • Other GI conditions e.g. IBD
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7
Q

If soemone presents with GI infection what must you ask about their:

  • Travel history
  • Drug history
  • Social history
A

Travel

  • Where, when, how long
  • Activities e.g. swimming?
  • Food and drink
  • Animal contact
  • Travel companions & household companions…. are they ill?

Drugs

  • Recent antibiotics
  • Proton pump inhibitors
  • Laxatives
  • Immunosupressant medications

Social history

  • Occupation (can help you figure out possible cause but also may have implications for returning to work)
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8
Q

Summarise the bristol stool chart

A
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9
Q

Should you tell microbiology if there is any travel history?

A

YES- so they can run approriate tests

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10
Q

Compare watery and inflammatory diarrhoea (generally)

A

Watery

  • Small intestine
  • Bloating/ cramping
  • Large volume leading to volume depletion

Inflammatory

  • Bloody diarrhoea
  • Smaller volume
  • Pain on opening bowels
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11
Q

State some conditions salmonella can cause

A
  • Gastroenteritis
  • Enteric fever
  • Bacteraemia
  • Osteomyelitis
  • Septic arthritis
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12
Q

State the two broad categories salmonella can be divided into

A
  • Typhoidal salmonella: cause enteric fever
  • Non-typhoidal salmonella: causes gastroenteritis
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13
Q

In which patient population is osteomyelitis common when there is an infection with salmonella?

A

Sickle cell patients

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14
Q

When examining someone with GI infection, what things should you look for to determine volume status

A
  • Mucous membranes
  • Blood pressure
  • Pulse
  • JVP
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15
Q

For non-typhoidal salmonella, state:

  • Gram stain
  • Shape
  • Transmission route
  • Incubation period
A
  • Gram -ve
  • Bacilli
  • Transmission: food, faecal-oral mechanisms, animals
  • Incubation: 8-72 hours
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16
Q

What GI organ does salmonella invade?

A

Small intestine

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17
Q

State some symptoms of someone who has non-typhoidal salmonella infection in GI tract

Is it self-limiting?

A
  • Nausea/vomitting
  • Fever
  • Abdominal cramping
  • Non-blood diarrhoea

Yes, usualy resolves in 2-3 days

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18
Q

For Campylobacter, state:

  • Gram stain
  • Shape
  • Transmission route
  • Incubation period
A
  • Gram -ve
  • Helical/spiral shaped
  • Faeco-oral route found in uncooked meat, untreated water and unpasteurised milk
  • ~3 days (can take up to 7 days)
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19
Q

State symptoms of someone who has been infected with campylobacter

Is campylobacter self limiting?

A
  • Abdominal cramping
  • Diarrhoea (can be bloody or non-bloody)
  • Fever
  • Malaise

Yes, but can last days to weeks. Consider treatment in immunocompromised, elderly or if infection severe

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20
Q

State 2 complications of campylobacter

A
  • Reactive arthritis
  • Guillain-Barre syndrome (immune system attacks peripheral nerves causing parathesia and/or paralysis which starts in hands and feet and moves more central)
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21
Q

What is Shigellosis?

A

Infection of intestines (bacterial dysentry) caused by Shigella bacteria

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22
Q

What is bacterial dysentry?

A

Bacterial infection of intestines that causes severe diarrhoea with blood

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23
Q

For Shigella, state:

  • Gram stain
  • Shape
  • Transmission route
  • Incubation period
A
  • Gram -ve
  • Rod
  • Transmission: faecal oral, food, water, person to person (usually by contaminated stools) due to low infectious dose
  • Incubation: 1-7 days
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24
Q

State symptoms of someone who has Shigellosis

Is Shigellosis self-limiting?

A
  • Bloody diarrhoea
  • Mucus
  • Abdominal cramping
  • Tenesmus

NOTE: nausea & vomitting usually absent as this is infection of colon

Yes, self limiting unless host is immunocompromsied

25
Q

A very small dose is all that is required to cause Shigella infection; true or false?

A

True; only 10-100 organisms needed

26
Q

Describe how Shigella infects the GI tract (think about where in GI tract it invades and what it does)

A
  • Invades colon
  • Destroys mucosa
  • Leading to blood diarrrhoea with mucus and abdo cramping
27
Q

Since Shigella has very low infectious dose, and is therefore easily spread, which patient groups must we take extra considertions for?

A

Those who may spread it e.g.:

  • Food handlers
  • Health care workers
  • Child care workers
28
Q

State some potential systemic complications of Shigella infection

A
  • Seizures (children)
  • Reactive arthritis
  • Haemolytic uraemic syndrome
29
Q

For enterotoxigenic E.coli (ETEC), state:

  • Gram stain
  • Shape
  • Transmission
  • Virulence factors (2)
A
  • Gram -ve
  • Rod
  • Transmission: food or water contaminated by human waste or person-to-person
  • Virulence:
    • Pili: bind to small intestine mucosa
    • Produces enterotoxins that cause oversecretion of Cl-ions into lumen and stop absorption of Na+ drawing water into gut lumen causing watery diarrhoea
30
Q

Describe how Enterotoxigenic E.Coli causes water diarrhoea

A
  • Uses pili to bind to small intestine mucosa and then colonise on it
  • Produces enterotoxins that cause oversecretion of Cl-ions into lumen and stop absorption of Na+ drawing water into gut lumen causing watery diarrhoea
31
Q

State symptoms of someone infected with Shiga-toxin producing E.COli

A
  • Bloody diarrhoea
  • Abdo pain

Can cause haemolytic uraemic syndrome (non-immune mediated haemolytic anaemia, thrombocytopenia, AKI)

32
Q

Why must you NOT treat Shiga toxin-producing E.Coli with antibiotics?

A

Makes it worse as antibiotics allow bacteria to produce more toxins

33
Q

For Clostridium difficile, state:

  • Gram stain
  • Shape
  • Tranmission
A
  • Gram -ve
  • Rod
  • Can be caused by antibiotics and spread by spores (faecal oral route)
34
Q

Describe how antibiotics can cause C-Diff overgrowth and state 4 antibiotics commonly associated with this

A

C-Diff part of normal bacterial flora, antibiotics reduce number of other bacteria allowing C-Diff to proliferate.

Antibiotics commonly associated:

  • Amoxicillin
  • Ampicillini
  • Cephalosporins
  • Clindamycin
35
Q

Can C-diff still be spread to others once antibiotics, that had caused C-Diff, have stopped?

A

Yes because spores can persist in environment for long time

36
Q

State some risk factors for devleoping a C-Diff infection

A
  • >65
  • Antibiotics
  • Prolonged hospitalisation
37
Q

State some potential complications of C-Diff

A
  • Colitis
  • Toxic megacolon
  • Perforation
38
Q

Name the two toxic products produced by C-Diff and state what each does

A
  • Enterotoxin A: stimulates excesseive fluid secretion
  • Cytotoxin B: cytotoxic causes disruption of protein syntehsis and cell cytoskeleton
39
Q

Can C-Diff have different severities?

A
  • Yes
  • Simpel diarrhoea to pseudomembranous colitis (inflammation of colon due to C-Diff infection)
40
Q

For norovirus, state:

  • DNA or RNA
  • Single or double stranded
  • Enveloped or non-enveloped
  • Tranmission
A
  • RNA
  • Single
  • Enveloped
  • Faecal-oral, direct contact
41
Q

State symptoms of someone infected with norovirus

Is it self limiting?

A
  • “Winter D & V”
  • Lasts up to 48 hours
  • Self-limiting
42
Q

Norovirus isn’t very infectious; true or false

A

FALSE- highly infectious

43
Q

For rotavirus, state:

  • DNA or RNA
  • Single or double stranded
  • Enveloped or non-enveloped
  • Transmission
A
  • RNA
  • Double stranded
  • Non-enveloped
  • Faecal-oral
44
Q

Is rotavirus highly infective?

A

Yes

45
Q

What age group is rotavirus common in?

A

Under 2’s (responsible for 1/2 severe diarrhoea incidents)

46
Q

Describe how rotavirus causes diarrhoea

A
  • Passes through stomach as able to survive acidic conditions
  • Binds to small intestine epithelia
  • Affects villi decreasing SA for absorption meaning more osmotic substances left in lumen
  • Also decreases amoutn of digestive enzyems produced
  • Creates hyperosmotic lumen which draws water in leading to diarrhoea
47
Q

Is there a vaccine for rotavirus?

A

Yes

48
Q

Is rotavirus self-limiting?

A

Yes, in an immunocompetent host

49
Q

For Cryptospordium,state:

  • Bacteria, virus, fungi or parasite
  • Intracellular or extracellular
  • Where in GI tract it can reside
  • Incubation period
A
  • Parasite
  • Intracellular
  • Resides in lumen
  • Transmission: contaminated water (often animal faeces that has contaminated it)
50
Q

State symptoms of someone infected with cryptosporidium

A
  • Mild diarrhoea
  • May be severe in immunocompromsied
51
Q

What is the common cause of travellers diarrhoea?

A

Enterotoxigenic E.Coli

52
Q

For giardia, state:

  • Bacteria, virus, fungi or parasite
  • Transmission
A
  • Protozoan parasite
  • Transmission: food, water, faecal oral
53
Q

Where in GI tract does giarda colonise in an infection?

A

Duodenum

54
Q

State symptoms of giarda infection

A
  • Mild to severe diarrhoea
  • Steatorrhea
  • Flactulence
  • Abdo cramps
  • Bloating
55
Q

For entamoeba histolytica, state:

  • Bacteria, virus, parasite, fungi
  • Incubation period
  • Transmission
A
  • Parasite
  • 2 weeks to years
  • Transmission: feacal contamination of food and water
56
Q

State symtpoms of infection with entamoeba histolytica

What disease can an infectionwith entamoeba histolytica be mistaken for? Why is this potentially very dangerous?

A
  • Diarrhoea (can be bloody)
  • Abdo pain
  • Can potentially invade the epithelial cells causing ulceration in colon
  • Hence, can be mistaken colitis
  • Treat UC with corticosteroids which reduce immune system and make infection worse
57
Q

Where in GI tract does entamoeba histolytica usually colonise?

A

Colon

58
Q

State 2 potential complications of infection with entamoeba histolytica

A
  • Amoebic dysentery
  • Amoebic liver disease (spread to liver and form abscess)
59
Q

Describe how we can prevent spread of GI infections

A
  • PPE
  • Isolation
  • Hand hygiene (NOTE: hand gel doesn’t work for killing C-Diffor Norovirus- best advice to always wash hands if GI infection)
  • Clean infected room with chlorine based disinfectant after discharge

S3: Gastrointestinal (18 decks)

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