E6. Gut dysbiosis and disease Flashcards
what is dysbiosis?
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
How can dysbiosis occur?
Medications (e.g. antibiotics), dietary changes, psychological and physicalstress (i.e. inflammation)
Why does dysbiosis matter?
-Linked to a range of illnesses and diseases
-Obesity, diabetes, cancer, gastric ulcers, depression, asthma
-IBD, arthritis, autoimmune disorders, eczema, dental cavities, acne
Describe recurrent Clostridium difficile infections
-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
Risk factors of C. Diff infection
-antibiotic exposure
-older ager 65+
-recent stay at a hospital or nursing home
-weakened immune system
-previous history of C. diff
How do we treat C. Diff?
-Stopping any antibiotics if possible
-Taking course of another antibiotic to treat the C. diff infection
… and staying hydrated
what is metabolic syndrome?
combination of linked conditions:
-Type II diabetes
-High Blood pressure (hypertension)
-obesity
How can metabolic syndrome occur?
Underlying aetiology is complex
… but is associated with gut dysbiosis
Evidence the gut microbiome influences the brain led to the microbiome-gut-brain axis concept…
-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
Short-chain fatty acids (SCFA) produced by bacterial fermentation of dietary fibre in colon have many benefits:
-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
Can we reverse dysbiosis to restore health?
FMT can be administered via:
-Upper GI tract (endoscopy, nasogastric tube or capsules)
-Lower GI tract (enema or colonoscopy)
FMT treatment for recurrent C. Diff
90% cure rate after single treatment vs. 25% for vancomycin
What is FMT and what can it treat?
Faecal Microbiota Transplants an can treat dysbiosis, recurrent C. Diff, autism, irritable bowel syndrome
What is gastroenteritis?
-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
Symptoms of gastroenteritis?
nausea, vomiting, diarrhoea and abdominal cramps, fever, fatigue
Causes of gastroenteritis?
infection, allergic reactions to medications or food, stress, diet, underlying conditions
Transmission of gastroenteritis?
-Typically faecal-oral route
-Contaminated water/food, travel history useful to explore
Treatment and management of gastroenteritis?
-Oral rehydration therapy (ORT), paracetamol
-Stay home for 48 hours, good hygiene practices
-Antidiarrheals (e.g. loperamide) and/or antibiotics
-Severity and cause-dependent
Describe Gastroenteritis and diarrhoea
-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
what are Protozoa?
small unicellular eukaryotes
Can be normal and pathogenic
Pathogenic protozoa?
-Giardia intestinalis causes giardiasis
-Cryptosporidium spp. cause cryptosporidiosis: Both notifiable diseases & pharmacists can help!
-Entamoeba histolytica causes amoebiasis and amoebic dysentery
Describe giardiasis
-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
Describe symptoms and treatment of giardiasis
-Symptoms: chronic diarrhoea, flatulence, nausea, stomach cramps, weight loss (within 1-14 days, lasting 1-3 weeks)
-Treatment: ORT or drug treatment if severe
Describe Cryptosporidiosis
-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
Describe bacterial Gastroenteritis
-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
Describe Campylobacteriosis
-Bacteria invade GI epithelium and macrophages, produce toxins that inhibit cell growth & damage DNA
Symptoms and transmission of Campylobacteriosis
-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
Treatment of Campylobacteriosis
-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
Describe Salmonellosis
Salmonella bacteria can cause of food poisoning
Bacterial cells can perforate intestinal wall
Enterotoxins disrupt ion and water transport
What are the symptoms, transmission and treatment with Salmonellosis
-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
Describe Escherichia coli
-E. coli bacteria can cause food poisoning
-Escherichia coli O157:H7 is Shiga toxin-producing
Toxin can rupture and destroy red blood cells
What are the symptoms of Escherichia coli
-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
Describe rotavirus
Rotavirus = 70% of cases of gastroenteritis
Highly contagious but vaccine available
Infect gut epithelia
Leading cause of paediatric gastroenteritis
Symptoms, transmission and treatment of rotavirus?
-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
Describe Norovirus
Norovirus = 20% of cases of gastroenteritis
Highly contagious; known as winter vomiting bug
Infect gut epithelia
Describe symptoms, transmission and treatment of norovirus
-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
Describe Gastroenteritis Diagnoses
ONE NOTE
