Microflora

Question 1

How many species of microorganisms live in the gut of animals?

Answer 1

• 1500

Question 2

What are the different types of pathogen?

Answer 2

• bacteria
• virus
• parasites
• fungi
• yeast

Question 3

How do commensal bacteria cause infections?

Answer 3

• 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

Question 4

What about pathogens that are not meant to be in body?

Answer 4

• exogenous infections

Question 5

What are true pathogens?

Answer 5

• cause disease in susceptible host
• primary pathogens
• satisfy Koch postulates
• have some virulence factors e.g. fimbrae, flagella, toxins

Question 6

What are the beneficial roles of normal microflora?

Answer 6

• 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

Question 7

What is the role of bacteria in gut health?

Answer 7

• 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

Question 8

What is the microbiome?

Answer 8

• all the genes of the microbes living in or on the animal
• for every 1 human gene - 100 associated genes in microbiome

Question 9

Role of skin microflora?

Answer 9

• barrier
• can be commensal, symbiotic or pathogenic
• commensal - CE
• Gram +ve
  
  • strep
  • staph
  • corneybacterium
• occasionally gram -ve
  
  • dermatitis

Question 10

What are some of the microflora of the URT and oral cavity?

Answer 10

• 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

Question 11

What are the microflora of the GIT?

Answer 11

• 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

Question 12

Describe the microflora of the hoof

Answer 12

• 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

Question 13

Describe the microflora of the eyes and ears

Answer 13

• 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

Question 14

What happens if the flora is disrupted?

*

Answer 14

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

Question 15

Roles of gut microbes?

Answer 15

• fat storage
• energy metabolism
• fat liver metabolism/ hepatic steatosis
• CVD
• tissue lipid composition
• periodontitis
• behaviour and motor activity
• enteroendocrine metabolism

Question 16

What is the relationship between microflora and diabetes?

Answer 16

• 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

Question 17

Why modulate microflora?

Answer 17

• 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

Question 18

How do you modulate microflora?

Answer 18

• pre and pro biotics
• synbiotics
• phage therapy
• enzymes
• pytochemicals
• next gen. growth promoters

Question 19

What are probiotics?

Answer 19

• 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

Question 20

What are the metagenomic approaches to understanding the microflora?

Answer 20

• FISH - automated confocal - colour stain bind to DNA
• flowFISH - 20 colour FACS
• next gen sequencing - 2 hours, 6000 genes

Question 21

What is next generation sequencing?

Answer 21

• 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

Question 22

What is 16S rRNA NGS Metagenomic studies?

Answer 22

• Universal PCR for 16S rRNA genes
• analysus on QIIME for taxonomic assignment
  
  • ID 15,000 species per sample
  • >500 genera identified