Staphylococcus bacteria Flashcards
two types of staphylococcus spp
- staph aureus
- CoN staph
microbiological characteristics of all staphylococci - 4
- occur as single, pair, triad or grape like clusters
- grow rapidly after 28-23 hours of incubation in 37 degrees
- grow in presence of oxygen
- differentiated using the coagulase test
general CoNs - 3
- very few are pathogenic
- part of the NORMAL FLORA
- generally have a benign symbiotic relationship with the host, become pathogenic after entry into the tissue and they breach cutaneous barrier
examples of infectious CoN staphh
- s epidermidis
- s haemophyticus
- saprophyticus
- lugdunensis
- hominis
S saprophyticus
- UTI
S epidermidis
- prosthetic related infections
- prosthetic valve endocarditis
- vascular graft infection
S heamolitycus
- second most common
Peritonitis
Endocarditis
Septicaemia
Wound
UTI
Burn
Joint
S lugdunensis
Endocarditis
Bacteraemia
Arthritis
UTI
3 differences between S aureus and CoN
so here im listing dilo tsa aureus
- usually not colonizer, but may be
- not in all skin (anterior nares, axilla, perineum)
- chronic carriage causes increased risk of infection
In order to survive, the pathogen needs to
transmit
survive
infect
be virulent
Sequence of events leading to disease
Colonisation
Invasion
Survival and multiplication
Avoidance
Toxins
leucocidin
cytotoxi that forms pores or holes on the cell
hyaluronidase
breaks down hyaluronic acid which makes tissue more permeable for it to penetrate
coagulase
coagulation of blood which causes blood to clot. preotects bacteria against phagocytosis
staphylokinase/fibrinolysins
breaks down fibrin clots
haemolysin
breaks down RBC for nutrient acquisition
when is coagulase produced
- produced in the early exponential pahse of growth to avoid local trapping hich hampers its spread
- thrombus formation which allows it to bind
staphylokinase/fibrynolysins
- trnasiently produced in the early exponential and late stationary groth phases
- protease activates plasminogen to plasmins which breaks down fibrin clot thus allowing for the extension of local infection
what does coagulation test test for
bacterial aggregration in the presence of plasma through the action of clumping factor
what type of disease does s.aureus cause- BIP SOMS
Brain abscess
Infective endocarditis
Pneumonia
Sepsis
Osteomyelitis
Mentrual toxic shock syndrom
Soft tissue infections
