M6 Staphylococcus Flashcards
what are some major strains of staphylococcus
s. aureus
s. epidermidis
what are some common features of staphylococcus
gram +ve non motile irregular shape aureole and facultative anaerobe catalase +ve oxidase -ve can be coagulase +ve or -ve
how common is s. aureus
20% colonisation
where is s.aureus common
anterior nares and perineum
nosocomial and community
what is MRSA
mainly nasocoimal
elderly and immunosuppressed
ICU
what is the colonisation of s.epidermidis
100%
where is s.epidermidis found
skin and mucous mems
what si a nosocomial infection
assc with forgein devices - catheters
what is the common direct contact transmission of staph
hand and skin or mucous
what is the common indirect transmission of staph
instruments
bedding
door handles
what si the way staph is air bourne
shedding of cocci from infected site into atmosphere
dust or squames
what kind of bac is staph
oppputunisit
what are staph means of entry
hair follicles and sebaceous glands damaged or diseased skin broken skin catheters post influenza pneumonia
what is the pathogenicity of s. aureus
superififcal lesions - build to abscess
systemic - life threat
toxinoses - toxic shock
what sit he carriage of s. aureus
anterior nares
perineum
hands
oral cav - age and pros
what is the significance of s. aureus
HAI/nasocomial
oral abscesses
head and neck - ottis media
what are the virulence factors of staph
attachement
evasion of host defences
invasion/ tissue penetration
what are some virulence factors
capsule coagulate fibrinogen bind protein TSST-1 adhesins kills leucocytes shock rash desquamation
what are adhesins
extracellular matrix molecules are present on epi, endo surfaces as well as a component of blood clots
what is imp about fibrinogen binding
fibriiognen cleave from fibrin monomers allows to colonise site
wha are some s aureus skin infection
folliculitis carbuncle - multiolbualr abscess impetigo abscess scalded skin syndrome
what are some subs used for evasion of host defences
protein A proteases superantigens lipases coagulate capsule
what are toxinoses
TSST-1 toxic shock syndrome toxin 1
rapid progression high fever, sore throat, muscle pain
what is the bacteria present in food poisoning
staphylococcal enterotoxin
what is SSS
scalded skin syndrome
exfoliatin toxins
neonatal
face, axilla, groin
what are superanitgens
bind to outside and staalises reaction in 1/10 T cells turning whole immune system on
assc with toxic shock
massive release cytokines
what is diagnostic criteria of TSST-1
fever 39
diffuse macular rash - erythroderma- water under skin
hypotension
organ systems failing
what does protein A do
bind to Fc region of IgG antibodies
produced by exponential growth
what is protein a
coagulase +ve
activation complenent
what do pretences do
cleave Ab, defnesins, platelet microbicidal proteins
destroy host tissue
hat are lipase, phospholipase and esterase
combat surfactants produced to disrupt bacterial mem
post exponentially expressed scavenging enzymes
what is Panton Valentine Leukocidin
PVL bicomponent toxin
sp toxicity for leucocytes
1-2% strains
assc with severe skin infections
what are PVL and alpha toxin linked with
CA-MRSA
responsible for necrotising pneumonia and contagious severe kin infections
what is necrotising pneumonia
preceding influenza like syndrome
rapid progression
acute resp distress
refractory hypoxamenia young and fit community acquired
what si coagulase
plasma
protective allows clot and ashore but also covers assess host proteins such as fibrin
wat does coagulase form
staphylothrombin promotes conversion of fibrinogen to fibrin and clotting
what is coagulase +ve example
synonymous with pathogenic staphylococci
what is an example of coagulase +ve an -Ve
+ve - s.aureus
-ve - s. epidermis
what is fnbA
fibronectin adhesin
what is cna
colagen ashesin
what is sdrE
bone sialo-bindig
what is hlg
gamma toxin (leukocidin)
what is ica
polysaccharide intracellular adhesin
what si themes common HAI strain
t032
what is the regulation of pathogenicity factors
transition to exponential protein a,fibronectin binding proteins, surface proteins, coagulase
late expo surface proteins tuned off
stationary has secreted proteins turned on
what si most common antibiotic treat
peniccilin
what is issue with penicillin
50-80% resistant (beta-lactamase +ve)
what is flucloxacillin
beta - lactase resistant use if can’t use penicillin
if allergy to penicillin what is used
erythromycin
