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SA gastro-intestine > S9) Gastrointestinal Infections > Flashcards

S9) Gastrointestinal Infections Flashcards

1
Q

Identify the 5-step clinical approach when dealing with GI infections

A
  • History (incl travel and exposure history)
  • Physical examination (incl hydration status)
  • Investigation (samples, tests)
  • Supportive treatment (±antimicrobial treatment)
  • Infection prevention & control measures
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2
Q

Identify 3 major causes of infective diarrhoea as well as the organisms involved

A
  • Bacteria: salmonella, shigella, campylobacter, enterotoxigenic E. coli, C.diff (gram positive)
  • Viruses: norovirus, rotavirus, adenoviruses
  • Parasites: cryptosporidium, giardia, entamoeba
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3
Q

Which organisms are observed in selective nutrient agars of stool cultures?

A

GRAM NEGATIVE:

  • Salmonella
  • Shigella
  • Campylobacter spp → most likely to cause symptoms for weeks
  • E.coli → most likely to cause bloody diarrhoea
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4
Q

A Campylobacter infection is a major cause of diarrhoea worldwide.

Where is it found?

A

The Campylobacter organism lives in the GI tract of animal hosts, especially poultry

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5
Q

Identify 3 methods of transmission for a Campylobacter infection

A
  • Contaminated food
  • Water
  • Direct contact with animals/animal products
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6
Q

Which organisms usually cause Campylobacter enteritis?

A
  • C. jejuni
  • C. coli
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7
Q

Identify 5 symptoms of a Campylobacter infection (may mimic appendicitis)

A
  • Abdominal pain & cramps
  • Diarrhoea (absent/bloody)
  • Nausea
  • Prodromal symptoms (fever, rigors, aches, dizziness)
  • Colitis
  • self limiting, so you will get ver it with some help of fluid resuscitation
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8
Q

Identify 5 acute complications of Campylobacter enteritis

A
  • Cholecystitis
  • Peritonitis (patients with peritoneal dialysis)
  • Rash (urticaria, erythema nodosum)
  • Septic pseudoaneurysm
  • Pericarditis & myocarditis
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9
Q

Identify 2 late complications of Campylobacter infections

A
  • Reactive arthritis
  • Guillain-Barré syndrome
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10
Q

Outline the treatment of Camplybacter enteritis

A
  • Supportive treatment
  • Antibiotics if severe, pregnant, elderly or immunocompromised (fluoroquinolone / macrolide)
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11
Q

What is Cyclospora cayetanensis?

A

Cyclospora cayetanensis is a coccidian parasite which is associated with travellers diarrhoea

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12
Q

Where is Cyclospora cayetanensis usually found?

A
  • Endemic in South and Central America, South Asia, South-east Asia, the Middle East and Africa
  • Outbreaks in Europe and North America associated with food contamination
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13
Q

How does a Cyclospora cayetanensis infection spread?

A

Faeco-oral transmission (food / waterborne)

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14
Q

Identify 6 symptoms of a Cyclospora cayetanensis infection

A
  • Anorexia
  • Nausea
  • Flatulence
  • Fatigue
  • Abdominal cramping
  • Watery diarrhea
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15
Q

Describe the duration of illness for a Cyclospora cayetanensis infection

A
  • Incubation period ~7 days after ingestion
  • Average course length of illness ~ 3 weeks
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16
Q

Outline the treatment of a Cyclospora cayetanensis infection

A
  • Supportive treatment – fluid rehydration
  • Antibiotics – trimethoprim-sulphamethoxazole
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17
Q

How can a Cyclospora cayetanensis infection be prevented?

A

Prevention – attention to food hygiene when travelling to endemic areas

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18
Q

What is a norovirus?

A

A norovirus is the most common cause of epidemic gastroenteritis and its peak incidence is in winter, affecting all ages, highly contagious, hard to wash away

infects small intestine and so get diarrhoea and vomiting die to delayed gastric emptying so vomit to relieve pressure trapped inside

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19
Q

Where do norovirus outbreaks usually occur?

A

Outbreaks associated with hospitals, schools, nurseries, restaurants, cruise ships, hotel resorts,

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20
Q

How is the norovirus transmitted?

A
  • Faeco-oral
  • Person-to-person
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21
Q

How long is the incubation period for a norovirus?

A

Incubation period 24-28 hours

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22
Q

In detail, explain how the norovirus is transmitted

A
  • <100 viral particles can cause transmission
  • Viral particles shed in stool and vomitus
  • Fomites can contaminate environment
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23
Q

Describe the treatment of a norovirus infection

A
  • Supportive treatment – fluid rehydration
  • No antiviral treatment available
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24
Q

Infection prevention and control are key in avoiding and managing outbreaks.

Describe the prevention of the norovirus outbreaks

A
  • Hand washing
  • PPE
  • Isolation
  • Environmental cleaning
25
Q

Identify 4 infective causes of bloody diarrhoea

A
  • Campylobacter
  • E.Coli
  • Salmonella
  • Shigella
26
Q

What is the route of transmission for Shigella infection?

A

Foecal-oral route

27
Q

How do you identify clinically that a child is dehydrated?

A
  • Xerostomia (tongue)
  • Skin turgor
  • Elevated HR
  • Low BP
28
Q

What kind of bacteria is Shigella?

A

Shigella is a gram-negative rod shaped anaerobic bacteria

can be spread from infected stools, person to person

29
Q

Identify a virulence factor of shigella

A

Shiga toxin

30
Q

Describe the 4-step mechanism used by Shigella to cause bacteria and its symptoms

A
  • causes bloody diarrhoea with mucus and abdominal cramping
31
Q

What type of organism is cryptosporidium?

A

Parasite (protozoa)

32
Q

What is the route of transmission for Cryptosporidium?

A

Foecal-oral route (often through contaminated water)

33
Q

Identify 3 methods used to diagnose parasitic infections of the GI tract

A
  • Stool samples
  • Blood tests
  • Endoscopy
34
Q

Outline the treatment of Cryptosporidiosis

A
  • Supportive treatment – fluid resuscitation
  • Anti-motility agents
  • Antiparasitic drugs (azithromycin & paromycin)
  • Antiretroviral therapy (HIV patients)
35
Q

Why is antiretroviral therapy necessary for the treatment of Cryptosporidiosis in HIV-infected patients?

A

Highly active antiretroviral therapy (HAART) can reduce the patient’s viral load to restore their immune response to a certain level so that the symptoms of cryptosporidiosis are resolved

36
Q

What methods are used to remove cryptosporidium oocytes from a swimming pool?

A
  • Hyperchlorination
  • UV Radiation
37
Q

what are some GI defences

A
  • signs, smell and memory
  • Saliva and tears (antibacterial enzymes)
  • gastric acid
  • small intestine secretions (bile)
  • Colonic mucus
  • anaerobic environment
38
Q

gut microbiome

A
  • more as we get deeper init the body
  • bacteria more than 20% of poo
  • harmful bacteria can’t compete
  • produces antimicrobial surfaces
  • develop baby immune system
  • produce some certain nutrients (vitamins K)
39
Q

what happened if we have reduced gut microbiome

A
  • obesity
  • IBS
  • response to chemo
  • response to insulin
40
Q

what are SCFAs

A
  • short chain fatty acids
  • produced by gut microbiome
  • butyrate → energy source for colonocytes and regulates gut environment
  • acetate → cholesterol metabolism
  • propionate → maintains satiety
41
Q

what things reduce and increase our gut microbiome

A
  • high fibre → INCREASES
  • sweeteners → reduce
  • gluten free diet → reduce
  • proton pump inhibitors → reduce
  • antibiotics - kill gut bacteria (increase)
  • probiotics - live bacteria in a good amount (increase)
  • prebiotics - feed bacteria (increase)
42
Q

what is FMT

A
  • old treatment where stool from healthy person is given to a sick person so the sick person gets the good gut microbiome
  • donors can be on antibiotics, laxatives and diet pills
  • can’t have a GI disease
  • completely screened
43
Q

how does salmonella invade body

A
  1. ingested and invades into small intestine cels by endocytosis
  2. taken up by macrophages in submucosa
  3. they carry salmonella to recticuloendothelial system
  4. bacteria multiply intra-cellularly
  5. hyperplasia and hypertrophy
  6. salmonella reenter bowel through the liver
  7. can infect the gall bladder and spread
44
Q

what are some symptoms of salmonella

A

nausea, vomiting and diarrhoea

spread by ingesting food and water contaminated with salmonella

45
Q

entero toxigenic E coli

A
  • it is a commensal bacteria if colon but can be a pathogen too
  • spread by faecal-oral route by contaminated water
  • if it makes it towards small intestine it will adhere to enterocytes and produce enterotoxins (toxins) toxic to gut bacteria
  • they cause hyper secretion of cl into the gut, na follows and so water will follow
  • this causes lots of diarrhoea
46
Q

which two pathogens can cause bloody diarrhoea

A
  • shigella
  • campylobacter
  • these both are to do with the large intestine
47
Q

what is potential HUS

A

heamolytic uremic syndrome:

→ anemia

→ thromocytopeina

→ AKI

caused by Shigella and campylobacter

48
Q

what is clostridium difficile

A
  • gram positive, anaerobic and spore forming
  • transferred via oral faecal route
  • spores will colonise gut and release toxins
  • A- enterotoxin results in excessive secretion and inflammation
  • B - cytotoxin
49
Q

symptoms of C.Diff

A
  • most are unsymptomatic
  • varying degrees of diarrhoea
  • abdominal cramping
  • rarely :- toxic megacolon
50
Q

how to treat C.Diff

A
  • remove offending antibiotic
  • fluid resuscitation
  • probiotics _ can restore some normality in the gut
  • metronidazole
51
Q

what can be a big precipitating factor in gastroenteritis caused by C.difficile?

A

antibiotics

52
Q

what is rotavirus

A
  • common under 5
  • double stranded, RNA spread oral - feacal
  • vomiting and fever followed by diarrhoea → chloride secretion (lose water)
  • SGLT1 disruption → can absorb sodium and glucose and remain in the lumen
  • reduces brush border enzyme function so wont be able to absorb as much
  • must manage dehydration
53
Q

name three parasitic causes of gastroenteritis

A

protozoa that effect the intestinal tract

  • cryptosporidium → sporozoa, can’t move
  • Giardia lamblia (flagellate) → can move
  • entamoeba - amoeba, move by extending cytoplasmic projections
54
Q

what is cryptosporidium

A
  • diseases caused by ingestion of an oocyst (these are recycled in faeces to continue cycle)
  • reproduces inside cells in the small intestine
  • watery diarrhoea, malabsorption as bruh border enzymes are effected and chloride secretion
  • supportive treatment
55
Q

giardia

A
  • symptoms are more common in children
  • spread with water
  • symptoms will only show 10+ incubation period
  • diarrhoea and cramping
56
Q

what is the life cycle of Giardia? and treatment

A
  1. cyst ingested → stomach acid can release parasite from cyst, multiples and damages small intestine, villous atrophy occurs
  2. parasite goes back into the cyst and excreted out to recycle process
  3. treat with antibiotics
  4. it can sometimes cause long term conditions like lactase deficiency
57
Q

what is entamoeba histolytica

A
  • most are asymptomatic
  • diarrhoea and lover abscess
  • transmitted via contaminated food or water
  • people who have just travelled
58
Q

how does entamoeba histolytica infect body

A
  1. parasite remains in cyst
  2. comes out in the large intestine
  3. can multiply in wall of colon
  4. trophozoites invade mucosa cause diarrhoea
  5. can spread to heart
  6. TREAT:
  7. anti-protozoals
  8. if severe colitis and megacolon then surgery
59
Q

travellers diarrhoea

A
  • E.Coli most common cause
  • passing 3 or more watery stools
  • greater than 14 days of symptoms
  • Give antibiotics
  • watch out for food and water precautions

SA gastro-intestine (19 decks)

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