E6 Gut dysbiosis and disease Flashcards
what is dysbiosis?
an imbalance of microbial species within a microbiome
what happens in dysbiosis?
- beneficial bacteria usually decrease in number and diversity
- other bacteria that may be harmful ten to increase in number
how can dysbiosis occur?
- medications (eg. antibiotics)
- dietary changes
- psychological and physical stress
- age
- puberty
- biological sex
how can antibiotics cause dysbiosis?
they can kill bad bacteria but Aldo good bacteria which can cause gut dysbiosis
why does gut 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
what is Clostridium difficile?
a type of bacteria that can cause diarrhoea
where is Clostridium difficile located and how can it cause infection?
- Clostridium difficile usually lives harmlessly in your colon
- if the balance of bacteria in the gut changes (dysbiosis), Clostridium difficile can cause infection
what kind of pathogen is Clostridium difficile?
opportunistic pathogen (pathobiont)
risk factors for Clostridium difficile
- antibiotic exposure
- older age (over 65)
- previous history of Clostridium difficile
- weakened immune system
- recent stay at a hospital or nursing home
how do we treat Clostridium difficile infection?
- stop any antibiotics use if possible
- taking course of another antibiotic to treat the Clostridium difficile infection
(and stay hydrated)
what is metabolic syndrome and who does it affect?
combination of linked conditions:
- type II diabetes
- high blood pressure
- obesity
- affects 1 in 3 older adults aged 50 or over in the UK
how can metabolic syndrome occur?
underlying aetiology is complex but is associated with gut dysbiosis
why does metabolic syndrome matter?
research shows the gut microbiome is linked to disease and there is evidence it has a role in obesity
what is the microbiome-gut-brain concept?
- evidence the gut microbiome influences the brain led to this concept
- gut microbiome is involved involved in the modulation of neurochemical pathways between GIT and CNS
short-chain fatty acids produced by bacterial fermentation of dietary fibre in the colon have many benefits. state some.
- influence intestinal mucosal integrity and function
- can cross BBB, neuroactive properties that directly influence the brain
- secretion of gut hormones (eg. glucagon-like peptide 1)
- brown adipose tissue activation
- regulation of liver function
- increased insulin secretion from pancreas
- immune regulation
what is the disruption in balance of SCFA linked to?
mood changes
mood disorders
overall health
what does FMT stand for?
faecal microbiota transplants
where can FMT be administered via?
upper GIT
- endoscopy (tube down throat)
- nasogastric tube (tube down nose into throat and oesophagus)
- freeze-dried capsules
lower GIT
- enema
- colonoscopy
compare the cure rates of C. diff infection with faecal microbiota transplants vs. vancomycin
- 90% cure rate after single FMT treatment
- 25% cure rate for vancomycin
who has NICE approved FMT treatment for?
adults who had had 2 or more episodes of C. diff infection that have not resolved with antibiotics
describe the improvement of C. diff infection in those with autism spectrum disorder with FMT
40% improvement after 1 month of capsules, sustained after 2 years
what are the 2 types of irritable bowel disease? what types of condition are they?
- ulcerative colitis
- Crohn’s disease
both autoimmune diseases
describe the use and effectiveness of FMT treatment in those with either type of IBS
ulcerative colitis
- 40% showed positive response after 1 month of treatment
Crohn’s disease
- preliminary studies suggest FMT may be effective
what is gastroenteritis?
- inflammation of the lining of the stomach and intestines
- acute condition typically lasting a few days to 1 week
symptoms of gastroenteritis
- nausea
- vomiting (for 1-2 days)
- diarrhoea (for up to 5 days)
- abdominal cramps
- fever
- fatigue
causes of gastroenteritis
- infection
- allergic reactions to medications or food
- stress
- diet
- underlying conditions
describe the transmission of gastroenteritis
- typically faecal-oral route
- contaminated water / food
- travel history is useful to explore
describe the treatment and management of gastroenteritis
- ORT
- paracetamol
- stay home for 48 hours
- good hygiene practices
- antidiarrheals and / or antibiotics
are antidiarrheals and / or antibiotics always used to treat and manage gastroenteritis?
- no
- they are severity and cause-dependent
- if it is caused by infection, want to expel infection asap so diarrhoea must occur and not be stopped
in gastroenteritis (and generally), what can diarrhoea cause?
- disturbance of water and electrolyte reabsorption in gut
- moderate to severe dehydration
- risk of infection spreading
give some statistics surrounding diarrhoea (eg. from gastroenteritis) disturbing water and electrolyte reabsorption in the gut
- a leading cause of child mortality
- 3rd leading cause of death in children under 5
- 20-30% of UK residents experience diarrhoea
give some symptoms surrounding diarrhoea (eg. from gastroenteritis) causing moderate to severe dehydration
- dark urine, thirst, lethargy, tachycardia (fast HR)
- hypovolemia (loss of blood volume) can cause dizziness
- severe cases may require hospitalisation and IV fluids
how and where can diarrhoea lead to the risk of infection spreading from gastroenteritis?
- hospitals, schools, care homes
- contaminated food production and water supply
what is infectious gastroenteritis in terms of the category of disease it falls under?
- it is a notifiable disease
- this means if someone presents with this, we have to report them online to the government so the statistics are recorded
what are protozoa?
small, unicellular eukaryotes
are protozoa harmful?
they are a normal part of our microbiome (commensal)… but some are pathogenic
what does the bacteria Giardia intestinalis cause?
giardiasis
what does the bacteria Cryptosporidium spp. cause?
cryptosporodiosis
what types of diseases are giardiasis and cryptosporidiosis?
notifiable diseases
what does the bacteria Entamoeba histolytica cause?
amoebiasis and amoebic dysentery
describe giardiasis cysts
- infective and transmitted in water, food or via hands / fomites
- can resist water treatment, boiling is needed
describe giardiasis trophozoites
- motile and attachment to epithelium in small intestine
- have flagella and adhesive ventral disk
symptoms of giardiasis
chronic diarrhoea
flatulence
nausea
stomach cramps
weight loss
within 1-14 days, lasting 1-3 weeks
treatment of giardiasis
- ORT
- drug treatment if severe
- should stay hydrated and try to clear it without drug
describe cryptosporidiosis cysts
- egg form
- infective and transmitted in water, food or via hands / fomites
- high chlorine tolerance, boiling is needed
describe cryptosporidiosis trophozoites
- cell form
- parasite the gut epithelium in small intestine
symptoms of cryptosporidiosis
- chronic watery diarrhoea
- nausea
- stomach cramps
- fever
- weight loss
- within 2-10 days, lasting 1-2 weeks
treatment of cryptosporidiosis
- ORT
- drug treatment if severe
describe the mortality rate of cryptosporidiosis
high mortality rate in children and infants
what is bacterial gastroenteritis usually caused by?
- food poisoning
common bacterial causes include:
- Campylobacter
- Salmonella
- Escherichia coli
where is Campylobacter most often found?
undercooked chicken
unpasteurised milk
untreated water
what foods is Salmonella from?
those such as:
meats
raw eggs
milk
dairy
where is E. coli most often from?
meat
salad products
unpasteurised milk
describe Campylobacteriosis in terms of its rarity, shape and action
- most common cause of food poisoning in the UK
- rod-shaped coil with flagella at both ends
- bacteria invade GI epithelium and macrophages (produce toxins that inhibit growth of healthy body cells and damage DNA)
symptoms of Campylobacteriosis
- asymptomatic in 25-50%
- diarrhoea (often bloody)
- fever
- stomach cramps
- nausea and vomiting
when do Campylobacteriosis symptoms start after infection and how long do they last?
- start within 2-5 days
- last 1 week
describe the transmission of Campylobacteriosis
- consumption of contaminated food such as:
undercooked meat (eg. poultry)
unpasteurised milk
untreated water
treatment of campylobacteriosis
- self-limiting (unpleasant but will clear on its own)
- ORT
- manage symptoms but antibiotics may be needed if severe
explain the use of antidiarrheals for campylobacteriosis
might make illness worse due to extended exposure to bacterial toxins
describe salmonellosis
- Salmonella bacteria can cause food poisoning
- bacterial cells can perforate intestinal wall
- enterotoxins disrupt ion and water transport
symptoms of salmonellosis
- sometimes asymptomatic
- diarrhoea (can be bloody)
- fever
- stomach cramps
when do salmonellosis symptoms start after infection and how long do they last?
- start within 6hours - 6days (can present very quickly)
- last 4-7 days
describe the transmission of salmonellosis
- eating contaminated food such as:
undercooked meat (eg. poultry)
unpasteurised milk
eggs
treatment of salmonellosis
- self-limiting
- ORT
- manage symptoms
- antibiotics may be needed if severe
describe the use of antidiarrheals in salmonellosis
might make illness worse due to extended exposure to bacterial toxins
describe E. coli infection. give specific example
- E. coli bacteria can cause food poisoning
- there are lots of different strains of E. coli
- Escherichia coli O157:H7 is Shiga toxin-producing E. coli
- toxin can rupture and destroy red blood cells so it is very problematic
symptoms of E. coli infection
- diarrhoea (often bloody)
- stomach cramps
- vomiting
when do E. coli symptoms start after infection and how long do they last?
- start within 3-5 days
- last 5-7 days
describe the transmission of E. coli infection
- consumption of contaminated food such as:
undercooked meat (eg. beef)
unwashed raw leafy vegetables
untreated water
treatment of E. coli
- self-limiting
- ORT
- manage symptoms
- antibiotics may be needed if severe
describe the use of antidiarrheals in E. coli treatment (be specific)
can make illness worse, due to extended exposure to Shiga toxin
what accounts for most cases of gastroenteritis?
viruses
describe rotavirus
- 70% of cases of gastroenteritis
- highly contagious but vaccine available
- infect gut epithelia
- leading cause of paediatric gastroenteritis
symptoms of rotavirus
diarrhoea
vomiting
nausea
fever
stomach pain
when do rotavirus symptoms start after infection and how long do they last?
- start within 1-2 days
- last 3-8 days
transmission of rotavirus
- faecal-oral, contact with infected vomit or faeces
- contaminated food / surfaces
what precautions must be taken if a baby has rotavirus?
parents must be careful when changing baby’s nappy
treatment of rotavirus
- self-limiting
ORT - rest at home to limit transmission (very contagious)
describe norovirus
- 20% of cases of gastroenteritis
- highly contagious (known as winter vomiting bug)
- infect gut epithelia
symptoms of norovirus
diarrhoea
vomiting
nausea
fever
stomach pain
headaches and body aches
when do norovirus symptoms start after infection and how long do they last?
- start within 1-2 days
- last 2-3 days
describe the transmission of norovirus
- faecal-oral
- contact with infected vomit or faeces
- contaminated food / surfaces
- outbreaks are common among people living close together
treatment of norovirus
- self-limiting
- ORT
- rest at home to limit transmission
gastroenteritis is a notifiable disease but many cases are not diagnosed or recorded. why is this?
- people stay at home and get better themselves without getting the specific cause determined
- there are actually billions of cases annually worldwide
causative agents are rarely determined directly for gastroenteritis. why? what happens instead?
- deductions are made based on duration / type of symptoms
- stool samples are only taken in severe cases and for those at more risk of complications
treatment for gastroenteritis is mostly non-specific and self-management. what does this include?
- ORT
- paracetamol
- nutritional replacement
- antibiotics used in severe cases but can cause complications
- antidiarrheals may not be advised due to increased exposure to certain toxins (eg. bacterial)
