LEC MOD 4: UNIT 2 Flashcards
classification of streptococci: smith and brown’s classification
based on hemolysis on 5% sheep blood agar medium
streptococci is homofermentative in which the sole product of glucose fermentation is
lactic acid
most streptococci are mesophiles
false. CAPNOPHILES
streptococci are facultative anaerobes
true
streptococci are non-spore-forming and catalase (-)
true
smith and brown’s classification involves
- a-hemolysis
- B-hemolysis
- y-hemolysis
- a’-hemolysis
denotes incomplete lysis of erythrocytes with reduction of
hemoglobin and the formation of green pigment. Hence, streptococci producing such pattern is called “green streptococci”
a-hemolysis
refers to the complete disruption of erythrocytes resulting to
clearing of the blood around the bacterial growth.
B-hemolysis
signifies absence of hemolysis thereby no change is seen in the
medium surrounding bacterial growth. streptococci producing such pattern is described as “indifferent streptococci”
y-hemolysis
a small zone of intact erythrocytes immediately adjacent to bacterial colony is surrounded with a zone of complete erythrocyte hemolysis. Maybe confused with B-hemolysis
a’-hemolysis (alpha prime-hemolysis)
classification of streptococci discovered by Rebecca Lancefield in 1930s
Lancefield classification
classification of streptococci discovered by Rebecca Lancefield in 1930s
Lancefield classification
Lancefield classification is based on
-group-specific antigens
group specific antigens are either
- cell wall polysaccharides
- AKA C-substance (human group A, B, C, F, G streptococci)
- Lipoteichoic acids (group D streptococci and enterococcus species)
group specific antigens are either
- cell wall polysaccharides
- AKA C-substance (human group A, B, C, F, G streptococci)
- Lipoteichoic acids (group D streptococci and enterococcus species)
group specific antigens are either
- cell wall polysaccharides
- AKA C-substance
- human group A, B, C, F, G streptococci
- Lipoteichoic acids (group D streptococci and enterococcus species)
streptococci classification based on temperature for growth particularly at 10C and 45C.
academic/bergey’s classification
consists of streptococci that do not grow at both 10C and
45C.
pyogenic group
includes streptococci which fail to grow at 10C but can be
recovered at temperatures up to 45C.
viridans group
are streptococci that grow at both 10C and 45C
enterococcus group
comprise of streptococci that are frequently recovered in dairy
products, can grow at 10C but fail to grow at 45C.
lactic group
