Microflora Flashcards
How many species of microorganisms live in the gut of animals?
- 1500
What are the different types of pathogen?
- bacteria
- virus
- parasites
- fungi
- yeast
How do commensal bacteria cause infections?
- only if there is another factor
- cause endogenous or opportunistic infections
- e.g. commensal bacteria on mucosal surfaces cause infection - if viral infection, trauma, surgery, immunosuppression etc
What about pathogens that are not meant to be in body?
- exogenous infections
What are true pathogens?
- cause disease in susceptible host
- primary pathogens
- satisfy Koch postulates
- have some virulence factors e.g. fimbrae, flagella, toxins
What are the beneficial roles of normal microflora?
- enzymatic digestion of ruminant feed
- synthesise vitamins/ precursors - e.g. Bcomplex, vit K from E.coli and bacteriodes fragilis
- Butyrate - improves enterocyte health
- controls multiplication of pathogens
- competetive exclusion (CE)
- Bacteriocins
- Immune stimulation
- physical disruption - stop bacterial adherance
What is the role of bacteria in gut health?
- foregut
- bacteria break down cellulose and use glucose for their own metabolism (fermentation)
- waste product of fermentation = VFAs - energy for animal
- hindgut
- bacteria ferment carbs to SCFAs
- bacteria convert nitrogenous compounds to ammonia and microbial proteins + synthesizes B vits
- SCFAs absorbed - energy for gut ep cells and role in absorption of water and Na
What is the microbiome?
- all the genes of the microbes living in or on the animal
- for every 1 human gene - 100 associated genes in microbiome
Role of skin microflora?
- barrier
- can be commensal, symbiotic or pathogenic
- commensal - CE
- Gram +ve
- strep
- staph
- corneybacterium
- occasionally gram -ve
- dermatitis
What are some of the microflora of the URT and oral cavity?
- diverse
- age, nutrition, gender, enviro
- lower RT usually free of microflora - but if infection etc - upper goes to lower
- URT:
- m. bovis
- m. bovirhinis
- pasteurella multocida
- mannheimia haemolytica
- haemophilus somnus
- histophilus somni
- oral cavity
- staph
- strept
- treponemes
What are the microflora of the GIT?
- Enterobacteria
- E.coli
- Proteus spp.
- Klebsiella spp
- citrobacter
- yersinia
- anaerobic
- clostridia
- bacteriodes
- fusobacterium
- lactic acid bacteria
- lactobacilli
- enterococci
- aerobes e.g. bacillus - oxygen from enterocytes
Describe the microflora of the hoof
- Bacteriodes melaninogenicus
- Peptococcus
- Campylobacter
- F.necrophorum - commensal in rumen and faecal matter + horses hoof - thrush
- D.nodosus - commensal in interdigital space in sheep - foot rot
- survive in soil for several months
Describe the microflora of the eyes and ears
- cerumen prevents the outer microflora getting in
- upper ear = strept, staph (+ve), pseudomonas (-ve)
- depends on ear type - e.g. pendulous - no oxygen
- conjunctiva = strept and staph
What happens if the flora is disrupted?
*
dysbiosis - unbalance/ maladaptation
long use of antibiotics - disrupts microflora - C.albicans overgrowth - thrush
Enterocolitis - caused by overgrowth of C.difficile - antibiotics
Enterotoxaemia - young calves - overfed concentrates - overgrowth of C. perfringens
Necrotic enteritis in poultry - overgrowth of C.perfrigens due to fish meal
Roles of gut microbes?
- fat storage
- energy metabolism
- fat liver metabolism/ hepatic steatosis
- CVD
- tissue lipid composition
- periodontitis
- behaviour and motor activity
- enteroendocrine metabolism
What is the relationship between microflora and diabetes?
- evident that gut microbes may shaoe the host metabolic and immune network activity
- T2D - low grade inflam condition
- high-fat diets alter gut microbiota
- increased translocation of LPS and bacteria into bloodstream
- endotoxaemia and insulin resistance
Why modulate microflora?
- livestock - exposed to stress - alter microflora
- lower weight gain
- diarrhoea
- higher morbidity/ mortality
- disease control
- reduce pathogen carriage e.g. campy
- welfare
- improve feed conversion rates
- better environment
- alternative to antimicrobials
How do you modulate microflora?
- pre and pro biotics
- synbiotics
- phage therapy
- enzymes
- pytochemicals
- next gen. growth promoters
What are probiotics?
- live microorganisms which when administered in adequate amounts confer a health benefit to host
- e.g. Lactobacillus, bifidobacteria, streptococci, enterococci
- do this by:
- out competition of pathogens
- reducing receptor sites
- modulating enviro
- modulating pathogen behaviour
- produce anti-microbials
- alter immune response - tell pathogens not to replicate
- out competition of pathogens
What are the metagenomic approaches to understanding the microflora?
- FISH - automated confocal - colour stain bind to DNA
- flowFISH - 20 colour FACS
- next gen sequencing - 2 hours, 6000 genes
What is next generation sequencing?
- sequencing used to identify all the organisms in a sample and evaluate their relative properties
- for bacteria - amplification of the 16s (18s for fungi) of all organisms and then sequenced
What is 16S rRNA NGS Metagenomic studies?
- Universal PCR for 16S rRNA genes
- analysus on QIIME for taxonomic assignment
- ID 15,000 species per sample
- >500 genera identified
