Lecture 6 Flashcards
Gnotobiotic
Study of animals living in a micro biologically defined environment, either germ free or colonized with known bacteria
Microbiota
The sum of all microorganisms (including bacteria,archaea, eukaryotes and viruses) that reside in and/or on a host or specified part of host
Ex: GI tract
What microbiota is the densest and most diverse in the gut, and in whole human body?
Colonic microbiota
The human body consist of?
Archaea, bacteria, virus, and eukaryotes.
Differences in fecal microbial community diversity composition and function have also been correlated with?
Crohn’s disease Ulcerative colitis Irritable bowel syndrome (IBS) C. Difficile-associated disease Acute diarrhea
Describe clostridium difficile
Gram positive
Anaerobic
Rod-shaped
Motile bacterium
C. Difficile spreads in what types of way and is notable for producing?
C. Difficile is a spore former
Notable for its ability to produce exotoxins
CDIs cause what
C. difficile infection case a spectrum of disease which range from mild diarrhea to pseudomembranous colitis
What type of pathogen is C. Difficile
An opportunistic pathogen
Where can C. Difficile colonize
Large intestine of human, domestic, and wild animals
What protects the large intestine from invasive pathogens and how does it do it?
It is protected by indigenous flora (fecal microbiome)
Microbes provide colonization resistance against pathogenic species through competition of nutrients and attachment sites of gut wall
What provides a niche for colonization. By intestinal pathogens?
Antibiotics provide a niche for intestinal pathogens because it disrupts the barrier of micro flora and diminish colonization resistance.
Reduction of these two phyla by antibiotics are important to the pathophysiology of C. Difficile
Bacteroides and Firmicutes
C. Difficile was identified as what in patient stool? What was the name of the disorder? What was this disorder associated with?
It was identified as cytoxin. With patients that where identified with the disorder pseudomembranous colitis. Which is frequently associated with anti-microbial use.
Clostridium difficile is acquired through?
The Ingestion of spores
Once C.difficile is acquired where does it go?
Once acquired spores resist acidity of stomach and germinate into the vegetative form in small intestine
Disruption of normal gut flora, typically by antimicrobial allows?
It allows C. Difficile to proliferate causing a broad spectrum of clinical manifestations.
Diarrhea, fulminant colitis, death
What is used to subset the colonization of C. Difficile
Antibiotics
People can be colonized with a non-toxigenic strain of C. Difficile. True or False?
True
There are non-toxigenic strains that do not produce toxins.
Progression to symptomatic CDI is due to?
Not producing a sufficient antibody response
For the toxin to remain asymptomatic what must the body do?
Mount a sufficient humoral response (produce antibodies)
Pathogenicity is dependent on these two diarrhea producing toxins?
Toxin A (TcdA) Toxin B (TcdB)
All toxigenic strains contain?
Toxin B (TcdB)
Several interventions targeting the intestinal microbiota have been used to maintain and improve host health. These include:
Probiotics Prebiotics Fecal transplant Immune modulators Phage therapy Antibiotics
