Intro to gut microbiology Flashcards
What makes up the intestinal microflora?
Bacteria
Fungi (moulds and yeasts)
Protozoa
Bacteriophage (viruses of bacteria)
What are the methods of enumerating bacteria?
Visual exam:
- does not show what bacteria
- does not assess viability
Culture:
- able to count colonies to calculate original number of bacteria
- qualitative and quantitative
Molecular detection
- detect species via nucleic acid
Describe how the gut flora is established
Fetus is microbiologically sterile until birth/hatching
Neonate acquires organisms from surface parts of birth canal and immediate environment
What host changes can impact gut microflora?
Age
Stress
Drugs
Genetics
Diet
Illness
What factors differ across the GIT attracting different flora?
What the bacteria can utilise to grow
GI adhesion factors
Motility
Toxin production
Invasion processes
What genes are essential for microflora to have in the GIT?
Surface structures for adhesion
Membrane integrity for tolerance of harmful factors
Motility to get to target
General gene regulation for stress responses to adapt to GI environment
Specific transporters to take up GI-specific nutrients
Invasion to sustain colonisation
Describe the role of microflora in natural immunity via competitive immunity in the GIT
‘natural’ competitive exclusion:
- existing bacterial flora present competitive barrier to incoming bacteria to prevent colonisation and/or infection
Competition for:
- space
- co factor elements
- carbon sources
How can antibiotics have a negative effect of the GIT?
antimicrobial can remove sensitive organisms from a particular niche
Space left is then repopulated by resistance bacteria (can be undesirable organism)
What is the problem with antimicrobial growth promoters?
Prolonged use will select for antibiotic resistance
=> reservoir of transferable antibiotic resistance
