Staphylococcus – Flashcards
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Unlock answers| betamethasone |
| 12.6 mg |
| Microscopic Morphorlogical Appearance of Staphlococcus |
gram positive cocci non-spore formers (can survive in relatively harsh condition) non-motile usually no capsule (aureus has capsule) |
| Hemolysin |
virulence factor- protein toxin lyse RBC cells by disrupting cell membrane |
| leukocidin |
virulence factor-protein toxin
lyses white blood cells by disrupting cell membrane |
| enterotoxin |
virulence factor- protein toxin
food poisoning |
| Toxic shock syndrome (TSST-1) |
virulence factor- protein toxin
stimulates production of interleukin (IL-1) by macrophages resulting in fever induction |
| coagulase |
virulence factor - enzymes
plasma clotting protein; converts fibrinogen to fibrin -coats bacteria with fibrin and prevents phagocytosis -aids in attachment |
| fibrinolysin |
virulence factor - enzymes
digests fibrinogen (fibrin clots) |
| hyaluronidase |
virulence factor - enzyme
"spreading factor"
digests hyaluronic acid round host cells: promotes invation |
| lipase |
virulence factor - enzyme
degrades lipids: allows bacteria to colonize oily skin |
| penicillinase |
virulence factor - enzyme
hydrolyzes penicillin; drug resistance |
| catalase |
virulence factor - enzyme
degrades H2O2; a toxic metabolic end product |
exfoliatin or epidermolytoc toxin |
virulence factor - enzyme
protease that causes peeling of superficial skin layers by dissolving intracellular bridges |
| protein A |
virulence factor- structural surface component
surface component linked to peptidoglycan layer of cell wall; inhibits antibody-mediated clearance of bacteria by binding to IgG (non competitively binds-> decreases antibody immunity) |
| lipoteichoic acid |
virulence factor- structural surface component
binds to tissue components; cell adhesion |
staphylococcus aureus
carriage location? carriage rate? |
major pathogen of genus staphylococcus
anterior noses, nasopharynx and skin
30-50% of healthy adults |
virulence factors/ species identification of staphylococcus aureus |
coagulase positive hemolysin leukocidin protein A capsule |
| toxins of staphylococcus aureus |
hemolysin, leukodin enterotoxin exfoliatin or epidermolytic toxin |
| superficial infections caused by staphylococcus aureus |
| localized cutaneous infections |
| toxigenic infections of staphylococcus aureus |
staphylococcal scalded skin syndrome SSSS (by exfolatin) toxic shock syndrome TSTT-1 gastrointestinal disease (by enterotoxin) |
superficial cutaneous infections symptoms, pathogenesis
|
pyodermic infection systemic infections
pimples, boils, carbuncles and impetigo symptom: pus formation, staphylococcus, pyogenic cocci |
| staphylococci invades skin at |
sebaceous gland opening hair folicle wound |
| primary infection sites for steph. aureus |
| faces, back of neck, buttocks |
| symptoms of s. aureus |
| edema, erythema, pain, pus |
| risk groups of s. aureus |
| elderly and young children with poor hygiene |
| virulent feature of SSSS |
exfolatin or epidermolytic toxin
spreads epidermal layer from the dermis, blistering and peeling of the skin, exposed red under layer
looks like burned skin |
mode of infection of SSSS
(how it starts, how it progresses) |
syndrome begins as an erythema around the mouth and nose
spreads rapidly to infect skin of the neck, trunk and extremities |
| risk group of SSSS |
infants, young children <4 yr neonatal infection |
| primary infected sites of SSSS |
umbilical cord and eyes low mortality rate |
| death of SSSS |
| secondary infection of the denuded skin by other bacterial pathogens |
| treatment of SSSS |
| topical antibiotic- mupirocin |
| incidence of infection of Toxic Shock Syndrome |
| usage of super absorbent vaginal tampons that was cellulose based |
| virulent feature of Toxic Shock Syndrome |
toxic shock syndrome toxin TSST-1 |
| mode of infection of Toxic Shock Syndrome |
super absorbant brands strongly bind to Mg++ ions low concentration of Mg++ triggers TSST-1 production which is absorbed into the bloodstream TSST-1 that stimulates T-lymphocytes to produce cytokines intravascularly resulting in endothelial cell damage-shock and multi-system organ failure |
| 10 days later of Toxic Shock Syndrome |
hands and soles of feet develop a sunburn-like rash which results in a peeling of the skin
"strawberry tongue" |
| severe symptoms of Toxic Shock Syndrome |
| shock and multi-organ failure |
| death rate of Toxic Shock Syndrome |
| 2-5% respiratory failure |
| source contamination of food poisoning |
| staphylococcal lesions of skin contaminates food then food is left unrefrigerated, room temperature grows s. aureus--> production of enterotoxin |
| virulence factor of food poisoning |
| enterotoxin |
| coagulase negative staphlococcus |
s. epidermis s. saprophyticus |
| route of infection of coagulase negative s.epidermis |
surgical procedures that involve the insertion of foreign bodies- heart, catheter, etc
attachment of bacteria to foreign body |
| infections of s. epidermis |
| endocarditis, urinary tract infection, wound infection |
| bacterial sensitivity or resistance to antibiotic |
novobiocin
s.epidermis: sensitive (no growth) s. saphrophyticus: resistant (growth)
under novobiocin disk |
| emerging superbug? |
MASA
methicillin resistant s.aureus |
