Normal microbial flora and pathogens Flashcards
What are the two main groups pathogens can be separated into?
Opportunistic and True pathogens
What are True Pathogens?
Infectious agents that acn cause disease in virtually any susceptible host, also known as primary pathogens
They also satisfy kochs postulates
What is the first of kochs postulates?
- The organism must be found in abundance
in animals suffering from the clinical disease,
but not from healthy animals.
What is the second of kochs postulates?
- The organism must be isolated from the
diseased animals and grown in pure culture.
What is the third of kochs postulates?
- The disease must be reproduced when a
pure culture of the organism is introduced into
healthy, susceptible animals.
What is the fourth of kochs postulates?
- The same organism must be re-isolated in
pure culture from the experimentally infected
animals
What are some of the beneficial roles of normal microflora?
It can be useful for the enzymatic breakdown of feed in ruminants
Certain vitamins or their pre-cursers are synthesised by the normal flora
* The normal flora plays a role in controlling the multiplication of pathogens:
What is the role of bacteria in the foregut?
The bacteria in the gut breaks down cellulose and uses the glucose for their own metabolic needs (fermentation)
As a waste product of fermentation, the bacteria releases VFA’s which the animal can then utilise for energy
What is the role of bacteria in the hindgut?
Bacteria ferments carbohydrates into short-chain fatty acids
Bacteria can then convert dietry and endogenous nitrogen compounds into ammonia and and microbial protein
* Absorption of SCFA provides energy for the gut epithelial cells and plays an important role in
the absorption of Na and water.
What are some microorganisms that reside on the skin?
bacteria, fungi, yeast and viruses
What kind of role do commensal bacteria play?
a protective role (competitive exclusion)
What are some bacteria commonly found in the skin flora
Mainly gram positive bacteria such as Staphylococci,
Streptococci, Corneybacterium
What kind of bacteria are found in the oral cavity?
Streptococci, Staphylococci and various anaerobic/ aerobic bacteria
Where is F. necrophorum present in the horse?
It is present as a commensal in the rumen and faecal matter
And a commensal of the interdigital space in sheep
Where is D. nodosus present in the hoof?
a commensal of the interdigital
space in sheep, causing foot rot only under
certain conditions.
