E6. Gut dysbiosis and disease

Question 1

what is dysbiosis?

Answer 1

an imbalance of microbial species within a microbiome
-Beneficial bacteria usually decrease in number and diversity
-Other bacteria that may be harmful tend to increase in number

Question 2

How can dysbiosis occur?

Answer 2

Medications (e.g. antibiotics), dietary changes, psychological and physicalstress (i.e. inflammation)

Question 3

Why does dysbiosis matter?

Answer 3

-Linked to a range of illnesses and diseases
-Obesity, diabetes, cancer, gastric ulcers, depression, asthma
-IBD, arthritis, autoimmune disorders, eczema, dental cavities, acne

Question 4

Describe recurrent Clostridium difficile infections

Answer 4

-Clostridium difficile (C. diff) is a type of bacteria that can cause diarrhoea
-C. diff usually lives harmlessly in your colon… not always ‘bad’
-If the balance of bacteria in your gut changes (dysbiosis), C. diff can cause an infection
-Opportunistic pathogen = pathobiont

Question 5

Risk factors of C. Diff infection

Answer 5

-antibiotic exposure
-older ager 65+
-recent stay at a hospital or nursing home
-weakened immune system
-previous history of C. diff

Question 6

How do we treat C. Diff?

Answer 6

-Stopping any antibiotics if possible
-Taking course of another antibiotic to treat the C. diff infection
… and staying hydrated

Question 7

what is metabolic syndrome?

Answer 7

combination of linked conditions:
-Type II diabetes
-High Blood pressure (hypertension)
-obesity

Question 8

How can metabolic syndrome occur?

Answer 8

Underlying aetiology is complex
… but is associated with gut dysbiosis

Question 9

Evidence the gut microbiome influences the brain led to the microbiome-gut-brain axis concept…

Answer 9

-Gut microbiome is involved in the modulation of neurochemical pathways (i.e. communication) between GI tract and CNS
-Not restricted solely to functions in GI tract
ONE NOTE

Question 10

Short-chain fatty acids (SCFA) produced by bacterial fermentation of dietary fibre in colon have many benefits:

Answer 10

-Influence intestinal mucosal integrity and function
-Can cross blood-brain barrier; neuroactive properties
-Secretion of gut hormones (e.g. glucagon-like peptide 1)
-Brown adipose tissue activation, regulation of liver function, increased insulin secretion from pancreas, immune regulation

Question 11

Can we reverse dysbiosis to restore health?

Answer 11

FMT can be administered via:
-Upper GI tract (endoscopy, nasogastric tube or capsules)
-Lower GI tract (enema or colonoscopy)

Question 12

FMT treatment for recurrent C. Diff

Answer 12

90% cure rate after single treatment vs. 25% for vancomycin

Question 13

What is FMT and what can it treat?

Answer 13

Faecal Microbiota Transplants an can treat dysbiosis, recurrent C. Diff, autism, irritable bowel syndrome

Question 14

What is gastroenteritis?

Answer 14

-Inflammation of the lining of the stomach and intestines
-Acute condition typically lasting a few days to 1 week
-Vomiting for 1-2 days; diarrhoea, up to 5 days

Question 15

Symptoms of gastroenteritis?

Answer 15

nausea, vomiting, diarrhoea and abdominal cramps, fever, fatigue

Question 16

Causes of gastroenteritis?

Answer 16

infection, allergic reactions to medications or food, stress, diet, underlying conditions

Question 17

Transmission of gastroenteritis?

Answer 17

-Typically faecal-oral route
-Contaminated water/food, travel history useful to explore

Question 18

Treatment and management of gastroenteritis?

Answer 18

-Oral rehydration therapy (ORT), paracetamol
-Stay home for 48 hours, good hygiene practices
-Antidiarrheals (e.g. loperamide) and/or antibiotics
-Severity and cause-dependent

Question 19

Describe Gastroenteritis and diarrhoea

Answer 19

-Disturbance of water and electrolyte reabsorption in gut
-Moderate to severe dehydration:
Dark urine, thirst, lethargy, tachycardia (>100 bpm)
Hypovolemia (loss of blood volume) can cause dizziness
Severe cases may require hospitalisation and IV fluids

-Risk of infection spreading:
Hospitals, schools, care homes
Contaminated food production and water supply

Question 20

what are Protozoa?

Answer 20

small unicellular eukaryotes
Can be normal and pathogenic

Question 21

Pathogenic protozoa?

Answer 21

-Giardia intestinalis causes giardiasis
-Cryptosporidium spp. cause cryptosporidiosis: Both notifiable diseases & pharmacists can help!
-Entamoeba histolytica causes amoebiasis and amoebic dysentery

Question 22

Describe giardiasis

Answer 22

-Cysts = infective and transmitted in water, food or via hands/fomites
Can resist water treatment; boiling is needed
-Trophozoites = motile and attachment to epithelium in small intestine
Have flagella and adhesive ventral disk
ONE NOTE

Question 23

Describe symptoms and treatment of giardiasis

Answer 23

-Symptoms: chronic diarrhoea, flatulence, nausea, stomach cramps, weight loss (within 1-14 days, lasting 1-3 weeks)
-Treatment: ORT or drug treatment if severe

Question 24

Describe Cryptosporidiosis

Answer 24

-Cysts = infective and transmitted in water, food or via hands/fomites
High chlorine tolerance; boiling needed
-Trophozoites = parasitise the gut epithelium in small intestine
-Symptoms: chronic watery diarrhoea, nausea, stomach cramps, fever, weight loss (within 2-10 days, lasting 1-2 weeks)
-Treatment: ORT or drug treatment if severe
ONE NOTE

Question 25

Describe bacterial Gastroenteritis

Answer 25

-Usually caused by food poisoning, with common bacterial causes including: Campylobacter: most often found in undercooked chicken, unpasteurised milk and untreated water Salmonella: from foods such as meats, raw eggs, milk and dairy Escherichia coli: most often from meat, salad products and unpasteurised milk -Some people are at higher risk of food poisoning More serious illness can develop ONE NOTE

Question 26

Describe Campylobacteriosis

Answer 26

-Bacteria invade GI epithelium and macrophages, produce toxins that inhibit cell growth & damage DNA

Question 27

Symptoms and transmission of Campylobacteriosis

Answer 27

-Symptoms: asymptomatic in 25–50%, diarrhoea (often bloody), fever and stomach cramps, nausea and vomiting (within 2-5 days, lasting 1 week) -Transmission: consumption of contaminated food, such as undercooked meat (e.g. poultry), unpasteurised milk, or untreated water

Question 28

Treatment of Campylobacteriosis

Answer 28

-Treatment: self-limiting, ORT, manage symptoms but antibiotics may be needed if severe -Antidiarrheals might make illness worse, due to extended exposure to bacterial toxins

Question 29

Describe Salmonellosis

Answer 29

Salmonella bacteria can cause of food poisoning Bacterial cells can perforate intestinal wall Enterotoxins disrupt ion and water transport

Question 30

What are the symptoms, transmission and treatment with Salmonellosis

Answer 30

-Symptoms: diarrhoea (can be bloody), fever and stomach cramps (within 6 hours - 6 days, lasting 4-7 days), sometimes asymptomatic -Transmission: eating contaminated food, such as undercooked meat (e.g. poultry), unpasteurised milk or eggs -Treatment: self-limiting, ORT, manage symptoms but antibiotics may be needed if severe Antidiarrheals might make illness worse, due to extended exposure to bacterial toxins

Question 31

Describe Escherichia coli

Answer 31

-E. coli bacteria can cause food poisoning -Escherichia coli O157:H7 is Shiga toxin-producing Toxin can rupture and destroy red blood cells

Question 32

What are the symptoms of Escherichia coli

Answer 32

-Symptoms: diarrhoea (often bloody), stomach cramps and vomiting (within 3-5 days, lasting 5-7 days) -Transmission: consumption of contaminated food, such as undercooked meat (e.g. beef), unwashed raw leafy vegetables or untreated water -Treatment: self-limiting, ORT, manage symptoms but antibiotics may be needed if severe Antidiarrheals can make illness worse, due to extended exposure to Shiga toxin

Question 33

Describe rotavirus

Answer 33

Rotavirus = 70% of cases of gastroenteritis Highly contagious but vaccine available Infect gut epithelia Leading cause of paediatric gastroenteritis

Question 34

Symptoms, transmission and treatment of rotavirus?

Answer 34

-Symptoms: diarrhoea, vomiting, nausea, fever, stomach pain (within 1-2 days, lasting 3-8 days) -Transmission: faecal-oral, contact with infected vomit or faeces, contaminated food/surfaces -Treatment: self-limiting, ORT, rest at home to limit transmission

Question 35

Describe Norovirus

Answer 35

Norovirus = 20% of cases of gastroenteritis Highly contagious; known as winter vomiting bug Infect gut epithelia

Question 36

Describe symptoms, transmission and treatment of norovirus

Answer 36

-Symptoms: diarrhoea, vomiting, nausea, fever, stomach pain, headaches and body aches (within 1-2 days, lasting 2-3 days) -Transmission: faecal-oral, contact with infected vomit or faeces, contaminated food/surfaces Outbreaks common among people living close together -Treatment: self-limiting, ORT, rest at home to limit transmission

Question 37

Describe Gastroenteritis Diagnoses

Answer 37

ONE NOTE