2/8: streptococcus, enterococcus, pneumococcus, stayphylococcus Flashcards
____ one of the first microbes identified to cause disease
streptococci
____ discovery lead to hygienic and aseptic practices in hospitals
streptococci
____ over 100 species
streptococci
Is streptococci spore forming?
NO
Is streptococci motile?
NO
Streptococci were originally classified into lancefield groups which classified them based on ____
classified based on major cell-wall carbohydrate antigens (groups a-h)
Pyogenic strep =
pus forming
Streptococci can also be classified based on hemolysis pattern. What are the 3 subgroups?
alpha hemolysis
beta hemolysis
gamma hemolysis
Alpha hemolysis group of streptococci = ___
partial hemolysis and green discoloration of hemoglobin
Beta hemolysis group of streptococci = ___
clear zone of complete hemolysis
Gamma hemolysis group of streptococci = ___
no zone of clearance at all
According to the lancefield group classificartion of streptococci, group A = ___
streptococci pyogenes
Streptococci pyogenes is transmitted via ___
GAS spreading by direct human contact of respiratory droplets
Streptococci pyogenes can infect ___
EXCLUSIVELY HUMANS
primarily in respiratory tract, blood, skin
Streptococci pyogenes has a hallmark feature of ____
pus formation
remember pyogenes = pus forming
What does the M PROTEIN of streptococci pyogenes do?
M cells bind to keratinocytes and prevents opsonization by complement
this resmebts mysoins (coiled strcture) the hypervariable region can have antibodies produced to it but there are over 200 serotypes and immunity to one doesn’t cross to another
The type of ____ determines what disease the GAS causes in streptococci pyogenes
M PROTIEN
Protein F of streptococci pyogenes does what?
binds to fibronectin
What does the hyaluronic acid capsule of the streptococci pyogenes do?
hyaluronic acid capsule = anti phagocytic
camouflages teh bacteria
interferes with adherence to epithelial cells, so hyaluronidase is secreted to digest the capsule and allow bacterial spread thorugh the tissue
Although the hyaluronic acid capsule of streptococci pyogenes is antiphagocytic and camouflages the bacteria, it also inhibits adherence to epithelial cells.
What does streptococci pyogenes do to overcome this?
secretes hyaluronidase to digest the hyaluronic acid capsule
this allows bacteria to adhere to epitheilial cells and spread throughout tissue
What does C5a peptidase of streptococci pyogenes do?
degrades C5a, blocks chemotaxis of phagocytes
