Microbiome Flashcards
what are the 4 main mechanisms of diarrhoea?
osmotic, (poor absorption of substances = excess water drawn out too much to absorb in colon)
hypermotility (faeces moving to fast for reabsorption of water, occurs in case of infection e.g. giardia parasite)
secretory (ion leakage e.g. in the case of E.coli), and inflammation
what are the 3 most common types of bacteria leading to gastroenteritis?
where do they come from
E.coli- undercooked, poor hygiene food
C.diff- common in hospitals after a course of antibiotics reduced competition allows them to thrive
salmonella (undercooked meat, eggs etc)
what effect does e.coli enterotoxins have on the brush border?
increase intracellular cAMP = hypersecretion of electrolytes and water
increase in intracellular cGMP reduces intestinal fluid uptake
how is gastroenteritis linked to a bacteria diagnosed?
stool sample taken, serial dilution of extract, grown on plates with antibiotics for most bacteria except those resistant e.g. salmonella
what does dysbiosis mean?
reduction in the diversity and richness of the microbiome / dysregulation in the bacteria population
what are the 4 main categories that contribute to the development of IBD?
environment (diet, medications) , genetics, intestinal barrier (permeability, goblet cells) and immune response
what is ulcerative colitis?
Ulcerative colitis- mucosal damage only, present in the distal colon (starts from the rectum and extends up)
Commonly occurs at 20-40 yrs old
what is Crohn’s disease
patchy nature along the entire GI tract, causes deeper full thickness damage and transmural inflammation extending all the way to the serosa
Commonly appears 15-30 years in life, can appear earlier also causes mucosal ulceration and extra-intestinal condition
what is a marker for IBD?
Faecal calprotectin acts as a marker for intestinal inflammation, neutrophils recruited to mucosa when infection / damage occurs they release calprotectin therefore It can be used as an inflammatory marker to asses the amount of neutrophils in the intestine
multiple test needed for Crohn’s disease as inflammation varies
what are the conventional treatments for Crohn’s disease / UC
anti inflammatory agents during flares ups / steroid usage
antibiotics? / dietary considerations
Colectomy ( stoma / bag - can be used to treat UC)
segmental restrictions in Crohn’s disease (remove disease portion, not preferable as inflammation can occur at other parts spontaneously)
what is the intestinal microbiome?
Highly complex and complicated network of bacteria, viruses, fungi, phage’s (bacterial viruses), yeast and archaea
that live synergistically with the host
what are the functions of the microbiome?
- Protection against pathogen invasion - the bacteria have colonisation resistance, that supresses the growth of pathogenic organisms that have survived the stomach
- Digestion of vitamins and nutrients / metabolic processes- fermentation of carbohydrates we are unable to digest, leading to short fatty acid chains that can be digested, synthesis vitamins, activation of pro-nutrients e.g. drugs, biotransformation of bile
- Other functions include immune system development, intestinal epithelial cell maintenance / renewal and gut- brain axis (how does it affect mental wellbeing?)
what are the 3 enterotypes?
Bacteroides, prevotella and ruminococcus
what is the enterotype?
A classification of gut bacteria
why is it useful to know an individuals enterotype?
determine how they will respond to a certain treatment/ get them to change their diet to change enterotype for a certain treatment
