Gastrointestinal Infections Flashcards
1
Q
What is acute gastritis?
Presentation
A
Inflammation of the stomach presenting with epigastric pain, N+V
2
Q
What is enteritis?
Presentation
A
Inflammation of the intestines presenting with abdominal pain + diarrhoea
3
Q
What is gastroenteritis?
Presentation
A
Inflammation from the stomach to the intestines presenting with pain, N+V + diarrhoea
4
Q
What defences does the GI system have against toxins?
A
- sight, smell, memory
- saliva: antibacterial enzymes
- gastric acid
- commensal bacteria
- colonic mucous
- bile in duodenum
- anaerobic environment: small bowel + colon
5
Q
Benefits of gut micro biome
A
- outcompete harmful bacteria for nutrients
- produces antimicrobial substances
- helps develop newborn immune system
- produce certain nutrients e.g. vitamin K
6
Q
What do bacteria in colon produce?
A
Short chain fatty acids
e.g. acetate, propionate, butyrate
7
Q
Function of the SCFAs produced by the bacteria in colon
A
- Butyrate: energy source of coloncytes + helps regulate gut environment
- Acetate: helps reduce satiety
- propionate: reduces serum cholesterol
CHECK may not be right
8
Q
What health conditions can decrease the diversity of the gut microbiome?
A
Obesity
Inflammatory bowel disease
9
Q
What is faecal microbiota transplant?
A
Therapeutic procedure in which you transfer healthy donor fences into GI tract of another to restore a balanced gut microbiome.
10
Q
Route of administration in faecal microbiota transplant
A
- nasoduodenal tubes
- upper GI endoscopy
- colonoscopy
- caecum >distributed throughout length of colon
11
Q
What condition has been treated with faecal microbiota transplant effectively?
A
Clostridioides difficile infection
12
Q
What is the criteria for selecting donors for faecal microbiota transplantation?
A
- 10-25 year olds
- not used antibiotics, laxatives or diet pills in last 3 months
- have no GI disease
- screen for hepatitis, HIV, inflammatory markers
13
Q
What is dysbiosis?
A
Imbalanced gut microbiome
14
Q
How can different diet choices affect gut microbiota?
A
- high fibre: increases health
- gluten free diet in those without coeliac disease: lowers number of key species
- sweeteners: disrupt diversity
- prebiotics: food for microbiota (good)
15
Q
Name bacterial infections of the gut + their gram stain
A
gram negative bacilli:
- salmonella
- campylobacter
- shigella
- enterotoxigenic E. coli
gram positive
- Clostridioides difficile
16
Q
Gram stain of salmonella bacteria
A
Gram negative bacilli
17
Q
Symptoms of salmonella
A
- Nausea
- Vomiting
- Non bloody diarrhoea
- Fever
- Abdominal cramping
18
Q
How is salmonella spread?
A
Ingesting contaminated food + water
19
Q
Outline a salmonella infection inside the gut
A
- salmonella endocytosed into enterocytes
- move to submucosa > taken up by macrophages
- macrophages transfer salmonella to reticuloendothelial system
- multiply inside cells
- causes lymphoid hyperplasia + hypertrophy
- re enter gut from liver
20
Q
Treatment of salmonella
A
Self limiting in 2-3 days
Fluids
21
Q
Gram stain of campylobacter
A
Gram negative bacilli
S shaped
22
Q
How is campylobacter spread?
A
Via faeco-oral route
Eating raw poultry
Drinking unpasturisied milk or untreated water
23
Q
Symptoms of campylobacter infection
A
- fever
- abdominal cramping
- profuse diarrhoea (can be bloody)
- vomiting
24
Q
Treatment of campylobacter infection
A
- Self limiting (few days - weeks)
- Fluid/electrolyte replacement
- antibiotics if bloody diarrhoea: clarithromycin
25
What infection is associated with eating poultry?
Campylobacter
(Salmonella)
26
Why do you get profuse diarrhoea in campylobacter infection?
Releases a cytotoxin
(Similar to cholera)
27
What does a shigella infection cause?
Shigellosis
28
Gram stain of shigella
Gram negative bacilli
29
How is shigella spread?
From infected stools
Person to person
Contaminated water or food
Often spread between family members
30
Symptoms of shigella infection
Bloody diarrhoea with mucous
Abdominal cramping
31
Outline a shigella infection in the gut
- endocytosed into **large intestinal + rectal cells**
- **break out from endocytosis vesicle**
- **multiple inside cell** where they are protected from macrophages
- mucosal abscess forms as cell dies
- causes **blood diarrhoea with mucous + abdominal cramping**
- shigella invade neighbouring cells
32
Who is shigella infection common in?
Young children
<5
33
Treatment of shigella infection
Self limiting
Resolves in a week
34
Complication of shigella
Shiga toxin can cause haemolytic uraemic syndrome
35
What is haemolytic uraemic syndrome?
Triad of:
- anaemia
- AKI
- thrombocytopenia
36
Describe enterotoxigenic E. coli
- Commensal of colon but can be a pathogen
- Gram negative bacilli
- Has flagellum
37
What is the common cause of travellers diarrhoea?
Enterotoxigenic E. coli
38
Outline enterotoxigenic E. coli infection
- ETEC adheres to enterocytes in **small intestine**
- **enterotoxin produced**
- causes **hypersecretion of Cl- ions**
- H2O follows
- **watery diarrhoea**
39
Why should antibiotics be avoided in E coli gastroenteritis if possible?
Shiga toxin produced can cause haemolytic uraemic syndrome
Antibiotics increased the risk of HUS
40
What are the gram negative bacilli which can infection the GI tract?
List from shortest to longest duration
*shortest*
ETEC
Salmonella
Shieglla
Campylobacter
*longest*
41
Describe Clostridioides difficle
Gram positive bacilli
Anaerobic
Spore forming
42
What is a major precipitating factor for Clostridioides difficle?
**Broad spectrum antibiotics**
Disrupts normal gut microbiota
43
What antibiotics are most associated with causing C difficle?
start with C:
- *clindamycin*
- *ciprofloxacin*
- *cephalosporins*
- *carbapenems* *e.g. meropenem*
44
What toxins does C difficle release?
- **Toxin A**: _enterotoxin_ > excessive secretion > diarrhoea + inflammation
- **Toxin B**: _cytotoxin_ > kills coloncytes
45
Symptoms of Clostridioides difficile
Mainly asymptomatic (during colonisation)
Diarrhoea (rarely bloody)
Abdominal cramping
Nausea
46
Diagnosis of C. difficile
- **C. difficile antigen**: glutamate dehydrogenase
- **identifying A+B toxins** by PCR or enzyme immunoassay
47
Severe rare complications of Clostridioides difficle infection
Pseudomembranous colitis
Toxic megacolon
48
Treatment of Clostridioides difficle infection
- removal of offending antibitoics
- fluid resuscitation
- probiotics (to replace microbiota)
- *metrondiazole* or *vancomycin*
- side room
- option of faecal microbiota transplantation for recurrent cases
49
What does pseudomembranous colitis look like on a colonoscopy?
Elevated yellow plaques
50
Most common cause of gastroenteritis
Viruses
51
What viruses can cause viral gastroenteritis?
Rotavirus
Norovirus
Adenovirus
52
What parasites cause parasitic gastroenteritis?
Cryptosporidium
Giardia lamblia
Entamoeba
53
What demographic does rotavirus effect?
Under 5s
54
Describe rotavirus
Double stranded RNA virus
55
Symptoms of rotavirus
- vomiting
- fever
- diarrhoea follow
56
Treatment of rotavirus
Manage dehydration due to fluid loss
57
Mechanism of rotavirus infection
- **increases Cl- secretion** > H2O follows > diarrhoea
- **SGLT1 disruption**: reduced movement of Na+/glucose into enterocyte > higher osmotic pressure in gut > H2O moves in via osmosis > diarrhoea
- **brush border dysfunction**: malabsorption
58
What demographic does norovirus effect?
Any age
(Don’t develop immunity)
59
Symptoms of norovirus infection
Vomiting
Water diarrhoea
Fever
60
Treatment of norovirus
Oral rehydration therapy
Lasts 1-3 days
61
What is the most common cause of non bacterial gastroenteritis?
Norovirus
62
Mechanism of infection of norovirus
- **brush border enzyme disruption**: infects small intestine + damages microvili
- **delayed gastric emptying** > vomiting
- **anion secretion** > water moves into gut > diarrhoea
63
Describe cryptosporidium
Protozoa - sporozoa
64
How is cryptosporidium infection spread?
Faecal oral route
Contaminated water with an animal faeces
65
Who is cryptosporidium infection common in?
Travellers
Campers
Areas of poor sanitation
66
Symptoms of cryptosporidium infection
Water diarrhoea
67
Treatment of cryptosporidium
- Self limiting
- Fluid replacement
- Anti-parasitics if at risk groups *e.g AIDS*
68
Describe gardia lamblia
Flagellated protozoa
69
Symptoms in gardia infection
- Mainly asymptomatic
- Symptoms more common children
- diarrhoea
- abdominal cramping
- last for up to 6 weeks
70
Diagnosis of giardia infection
Stool testing (NAAT or enzyme immunoassay testing)
71
Treatment of giardia
Fluid replacement
Antibiotics *e.g. metronidazole, tinidazole*
72
Describe the life cycle of giardia parasite
1.
- _cyst in ingested_
- **stomach acid/pancreatic enzyme release parasite from cyst**
- **multiplies** in small intestine
- **damages proximal small intestine**
2.
- _parasite returns to cyst stage in colon_
- cycle repeated
73
Describe entamoeba histolytica
Amoeba protozoa
74
Symptoms of entamoeba histolytica infection
Most asymptomatic
Bloody diarrhoea
Liver abscesses (rare)
75
Treatment of entamoeba histolytica
Anti protozoals
*metrondiazole*
76
Describe the infection of entamoeba histolytica
- cyst ingested
- **parasite leaves cyst in colon**
- **trophozoites invade mucosa** > bloody diarrhoea
- infection can spread to liver > liver abscess (rare)
- cysts pass out in faeces > infect others
77
What parasitic infection is most likely to cause persistent diarrhoea?
Gardia
78
What bacteria can cause haemolytic thrombocytopenia ureamia?
Shigella
Campylobacter
79
Post-gastroenteritis complications
- lactose intolerance
- IBS
- reactive arthritis
- Guillian-Barre syndrome
- haemolytic uraemic syndrome
80
What infections can cause bloody diarrhoea
- shigella
- campylobacter (sometimes)
- amoebas
81
What opportunistic GI infection can occur in HIV patients with CD4 <200?
Cryptosporidium
82
What GI infections can cause vomiting?
Salmonella
Campylobacter
Rotavirus
Norovirus
