Bacteriology 7: streptococci Flashcards
What kind of bacteria are streptococci?
- Gram positive cocci in chains
- Facultative anaerobic
How many streptococci have veterinary importance?
9
- 3 in horses
- 3 in cattle
Where do streptococci come from?
- Widely distributed in nature
- May live in environment as saphrocytes
What is the most common failure of ABX tx?
Failure of client complience
Where are streptococci pathogenic species usually found?
- On the mucus membranes of upper respiratory tract
- Lower genitourinary tract
- GIT
Is streptococci part of normal flora?
YES
Is streptococci pathogenic?
YES some strains can be on only carrier animals
How does streptococci cause disease?
- Range of virulence factors
Mechanisms that help streptococci cause disease?
- Avoid phagocytosis
- Kill phagocytes and cause inflammation
- DO NOT survive intracellular
How to streptococci avoid phagocytosis?
- M protein
- Capsules
What is M protein
- major virulence factor
- anti-phagocytic properties
- Induce antibody production which become protective
*** Used in vaccines
How to streptococci kill phagocytes?
With exotoxins (hemolysin)
- B-hemolysins
- A-hemolysins
What patterns does b-hemolysins make? Who is it common in?
A clear hemolysin pattern
- Domestic species (horses, cattle dogs)
What pattern to alpha-hemolysins create? Who is it common in?
- Greenish hemolytic pattern
- Cattle, humans, and becoming more so in dogs
Are non-hemolytic patterns pathogenic?
No
