Staph & Strep Flashcards
1
Q
Describe how Staphylococcal Infection can be contracted?
A
- transmission is via direct contact from person to person but also from contaminated clothing, sheets & medical instruments
2
Q
What different factors affect infection ?
A
- site infection
- immune status of host
- different virulence factors
3
Q
What are the 3 categories of disease ?
A
- Noninvasive
- Cutaneous
- Systemic
4
Q
What are 3 virulence factors ?
A
- evasion from phagocytosis
- production of enzymes
- production of toxins
5
Q
Describe Group A streptococci
A
- infects the pharynx & skin
- abscesses are short lived
- large inoculum is required & usually disease results when competing microbiota are depleted or immune status is poor
- can be spread from person to person
6
Q
Describe Streptococcus pneumoniae
A
- 92 strains known infect humans
- lacks Lancefield antigens
- alpha-haemolytic = aerobic conditions
- beta-haemolytic = anaerobic conditions
7
Q
Describe Staphylococci Gram Stain
A
- gram positive cocci
- singly & grape-like clusters
- facultatively anaerobic
- non-motile
- salt tolerant
8
Q
Describe Streptococci Gram Stain
A
- gram postive cocci
- pair & chains
- facultatively anaerobic
- non-motile
9
Q
How can you distinguish between staph & strep using a catalase test ?
A
- Staphylococci = catalase positive
- streptococci = catalase negative
10
Q
Describe the Coagulase test
A
- Staphylococcus are differentiated by the ability to clot plasma by enzyme coagulase
- binds plasma fibrinogen, causing the organism to agglutinate/clot
