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- exotoxins produced by gram-positive cocci species
- able to destroy red blood cells & hemoglobin
Blood agar is sometimes called? why?
- Sheep blood agar
- because it contains 5% sheep blood in tryptic soy agar base
3 major types of hemolysis are:
complete destruction of RBC's and hemoglobin, results in a clearing of the medium around the colonies
pratial destruction of RBC's and produces a greenish discoloration of the agar around the colonies
non-hemolysis and appears as simple growth with no change to the medium
hemolysins produced by sreptococci are called? what are their 2 forms?
- types: O & S
- oxygen labile
- expresses maximal activity under anaerobic conditions
- express itself optimally under anearobic conditions
streak stab technique:
- easiest method of providing an enviroment favorable for streptolysisns on blood agar
- plate is streaked for isolation and stabbed
- stab encourages streptolysin activity because of the reduced oxygen concntration of the subsurface enviro
blood agar is used for isolation and cultivation of many types of? differentiates?
- fastidious bacteria
- based on hemolytic characteristics, especilly w/in streptococcus, enterococcus and aerococcus.
Blood Agar Results:
clearing around growth
greening around growth
No change in the medium
- organisms hemolyzes RBC's completely (beta)
- organism hemolyzes RBC's partially (alpha)
- Organism does not hemolyze RBC's (gamma)