The Microbiota of the GI Tract 2 Flashcards
What are some factors that affects the gut microbiota?
Environment
Diet
Life stage
Disease
Faecal transplant
Prebiotics
Antibiotics
Probiotics
Is microbial dysbiosis (imbalance) a cause or consequence of disease?
It is still unknown
What are examples of diseases that can be caused by microbes that normally live asymptomatically in the host?
MRSA infection
Strep throat
Gingivitis
Acne
Meningitis
Pneumonia
C. Difficile diarrhoea
Thurst
Urinary tract infections
Gastric cancer
What is an example of a disease that can occur when gut microbes translocate to other body sites?
Sepsis
Where can gut bacterium often translocate to?
Bloodstream
How has the incidence of infectious and immune diseases changed over the last 70 years?
Infectious diseases have been declining
Immune diseases have been increasing
Why has the incidence of infectious disease declined over the last 70 years?
Better disease treatment
Vaccination
Health standards
What has the incidence of immune diseases rised in the last 70 years?
Diet
Hygiene
Effect on microbiota possibly
What does inflammation in IBD result due to?
Dysregulated host immune response to the gut microbiota
How is the gut bacterial diversity different for people with IBD?
Less diverse than people who do not have IBD
What does it mean that IBD typically manifests in a non-uniform manner?
Patients have regions of healthy tissue adjacent to inflammed regions
What is an example of a bacterium that is elevated in Crohn’s disease?
Enterobacteriaceae
Why is it very difficult to entangle cause from effect?
Many features of IBD itself could affect the microbiota, such as antibiotic use, inflammation, diarrhoea (affects transit time), host diet and host genotype
What can reduced bacterial diversity and increase in Enterobacteriaceae occur due to?
Broad spectrum antibiotic use
Inflammation
What impact does antibiotics have on the gut microbiota?
Decreases diversity and increases Enterobacteriaceae
How does inflammation change the gut microbiota?
How does diarrhoea alter the gut microbiota?
Decreased transit time alters microbial composition
How does the hosts diet alter the gut microbiota?
Less fibre causes changes to microbiota composition
What is currently being research in terms of the contents of the gut microbiota?
Manipulating the microbioa to redress the dysbosis and relieve symptoms of IBD
How can the microbiota of the gut possible be manipulated to fix a reduction in Faecalibacterium prausnitzii numbers?
Provide specific prebiotics designed to boost numbers of F. Praesnitzii
Design F. Praesnitzii as a biotherapeutic agent
How can the microbiota of the gut possible be manipulated to fix an increase in Enterobacteriaceae numbers?
Reduce antibiotic use to prevent decline in commensals
What, and how, do the two main species of bacteria change in IBD?
Faecalibacterium prausnitzii decreases
Enterobacteriaceae increases
What can be changed in someones diet to increase bacterial diversity?
Increase fibre
What does the success of existing probiotics/prebiotics depend on?
Specific strain
What is a probiotic?
Live microorganism which, when administered in adequate amounts confer a health benefit on the host (basically add live bacteria)
What is a prebiotic?
A substrate that is selectively utilised by host microorganisms conferring a health benefit (basically food for resident bacteria)
What are the conclusions of most studies that look at the effectiveness of probiotics?
They are beneficial in treatment and prevention of GI diseases
What are the different mechanisms of action for probiotics?
Do probiotics become permanent residents in the gut?
No, but their products and actions can still be beneficial under certain circumstances
Why is the species and strain important when selecting probiotics?
Different species (even strains) have different effects
Individual response varies due to existing variation in microbiota
What are examples of prebiotics?
What are the health benefits of prebiotics?
Improved gut function
Management of inflammatory bowel disease
May reduce risk of colon cancer
GOS/FOS supplementation of infant formula increased bifidobacteria numbers
FOS/insulin increase calcium absorption and bone health
Consumption of prebiotics instead of sugards can lower glycaemic index
How do prebiotics improve gut function?
Stook bulking and faster gut transit
How do prebiotics reduce the risk of colon cancer?
Reduced DNA damage and cell proliferation
Faster gut transit time
What has banned the use of the words probiotic and prebiotic?
Current European Food Safety Authority (EFSA) regulations
What are some permitted health claims involving microbiota?
Regular consumptionof at least 3g per day of B-glucan fibre found in oats/barley can reduce the risk of heart disease
What are claims recomended by WHO involving gut microbiota?
Increased consumption of dietary fibre can reduce the risk of colon cancer
Consumption of prebiotics improves calcium uptake
What are consequences to the microbiota when exposed to antibiotics?
Kill commensals as well as pathogens
Leads to low diversity
Can cause spread of antibiotic resistant bacteria
In terms of the microbiota, what happens during and immediately post-antibiotic treatment?
Decreased microbial diversity
Opportunity for pathogen colonisation
C. Difficile expands to occupy empty niches, causing overgrowth that produces toxins
What does CDAD stand for?
C. Difficile Associated Diarrhoea
What does an overgrowth of C. Difficile cause?
CDAD
What are the main symptoms of CDAD?
Diarrhoea
Abdominal pain
Fever
Do antibiotics have an effect on C. Difficile spores?
No, they are resistent
What can be said about strains of C. Difficile and antibiotics?
Some strains are antibiotic resistent
What is the initial treatment for CDAD?
Antibiotic therapy (cures about 75% of patient)
What is the best treatment for CDAD when antibiotics do not work?
Faecal microbial transplantation (FMT)
What can failure ot faecal microbial transplantation (FMT) to treat CDAD lead to?
Death
How does FMT work?
What does the success rate of FMT depend on?
Clinic experience
Application method
Pre-treatment
No subsequent antibiotic threatment
What infections do faecal transplants only work on?
C. Difficile
What is the criteria for bacteria to be used for a faecal transplant?
Sensitive to antimicrobials
Easy to culture
Representative of gut commensal bacteria
Added in relative abundances representative of composition of healthy gut
