Ecosystem skin & skin immune system Flashcards
What niches are available for the skin microflora?
The coat
Hair follicle
Epidermis
Skin surface
What are the reasons for microorganisms living on the skin?
Nutrients
Good climatic conditions (microenvironment)
Physical protection
Requirements can be site specific
What classes of commensals are there?
Nomads, transients and residents
Why is it important to know which category an organism falls into?
If there is an infection/diseases caused by a particular organism, it is important to know whether to clear it from the skin partially, or completely.
Name some of the organisms that can colonise the skin.
BACTERIA Staphylococci Micrococci Coryneforms Propionibacterium acnes
YEAST
Malassezia pachydermatitis
ACARIDS
Demodex
Where do neonates normally acquire their commensals from?
Usually the mother, often from fauna in her oral cavity after birth. Also partly from the environment.
What areas of the body have large amounts of commensals?
Junctions between the mucosa and epithelium e.g. anus, oral cavity, conjunctivat etc.
What are the commonest coagulase positice and coagulase negative bacteria in cats?
+ve - S. pseudintermedius
-ve - S. simulans
Are fungi other than Malassezia pachydermatitis commensal?
No - they appear to be transients
What organism causes ringworm?
Microsporum canis.
What is important to find out is an animal gets a disease from an organism that is part of its commensal microflora?
Why has it got the disease!
What are the factors that could lead to a disease caused by normally commensal organisms?
Microorganism factors -
Numbers (in high numbers some bacteria produce toxins)
Virulance factors
Interaction between microorganisms
HOST factors -
Nutrition, microclimate, hormones, stress
Skin defence deficiencies
Change in ENVIRONMENTAL conditions
What are the ways in which the skin defends against infection?
Physical Barrier - desquamation Chemical - secretions Immunological - Antimicrobial peptide secretion Cellular defence Humoral defence
