2. Use trypticase soy broth for a general purpose medium
3. Use a MacConkey Agar plate for selective/differential medium
pure culture isolation path for a small colony?
1. Flame streak plate to get individual colonies
2. Use trypticase soy broth for a general purpose medium
3. Blood Agar for enriched medium
What is blood agar supplemented with?
5% sRBC
what is the function of the blood agar plate?
detects hemolysins
How does the blood agar plate detect hemolysins?
enzymes produced by bacteria that breaks down whole red blood cells.
What are the hemolytic paths for staphylcoccus?
hemolytic or non-hemolytic
What are the hemolytic paths for streptococcus?
alpha
alpha hemolysis
partial breakdown of blood cells
why does the alpha hemolysis produce a green color?
by hydrogen peroxide produced by the bacterium
Beta hemolysis
complete breakdown of red blood cells due to production of bacterium of the exotoxin
Gamma Hemolysis
no hemolysis
What are the two different mediums for the MacConkey Agar.
Selective Medium and Differential Medium
Selective Medium
Selects one type of organism over another. selects gram negative bacilli and inhibits gram positive microorganism
Concentration of crystal violet dye in the medium inhibits growth of the gram _______ bacteria.
positive
Differential Medium
differentiates one organism from another through a biochemical reaction; Differentiation of lactose fermenting organisms from non-lactose fermenting gram negative enteric bacteria.
natural red dye is a _______ indicator
pH
Lactose Fermenter (Lac+) function
utilizes lactose is the medium
Lactose Non-Fermenter (Lac-) function
cannot utilize lactose and will use peptone instead which forms ammonia resulting in an increase in the pH of the agar which produces colorless colonies
Why is enterococci tacked onto streptococci listings?
they deal with the intestinal
What is the arrangement of staphylococcus?
irregular clusters
What is the arrangement of streptococcus?
pairs/chains
How do you get a genus differentiation between staphylococcus and streptococci?
Catalase Test
Staphylococcus is catalase __________.
positive
Streptococcus is catalase __________.
negative
What can be used to differentiate between Staph Aureus and staph epidermidis
Coagulase Test, free coagulase
what are the two types of coagulase tests?
cell bound coagulase
What is the cell bound coagulase test?
clumping factor slide test
What is the free coagulase test?
extracellular enzyme tube test that uses CRF to make fibrin from fibrinogen.
What hemolytic path does the viridans group undergoes?
alpha hemolysis
What is MSA?
Mannitol Salt Agar
what is the selective media in MSA?
additive 7.5% NaCl
What is the differential media in MSA?
carbohydrate mannitol; monitor the change of pH of phenol red.
What does staph aureas do to MSA?
ferments mannitol
What does staph epi do to MSA?
does not ferment mannitol
Staph aureus hemolytic path?
hemolytic
staph epi hemolytic path?
non-hemolytic
What are the 4 biochemical properties that can be used to ID streptococci?
growth in 6.5 NaCl
sensitivity to bacitracin or optichin
bile solubility
bile esculin agar (hydrolysis of esculin)
What are the three determinations for enterococci as opposed to streptococci?
growth in 6.5% NaCl
tolerate 40% bile salts
esculin hydrolysis - bile esculin agar
When esculin is hydrolyzed it produces...
glucose + esculetin
esculetin + __________ makes black colored complex
ferric citrate
How do you differentiate strept. pneum. from other alpha hemolytic streptococci?
optochin sensitivity
bile solubility test - bile soluble (cells lysed) [bile activates on autolysin (cellular amidase) that lyses bacteria
How do you differentiate strept. agalactiae from other beta-hemolytic steptococci?
Positive CAMP test
How do you know if you have a positive CAMP test?
clear "arrow-shaped" zone of hemolysis due to the two lysins produced by stap. aureus and stept agalactiae.
What culture(agar plate) test is used for Group A streptococci (strep. pyog)
enriched media (blood plate - beta hemolysis)
What is the way to id the strep. pyog species from the other?
susceptibility to bacitracin
How do you detect antigens in the strept. pyog (group a streptococcus)
clinical specimen - throat swab
blood plate agar
direct group A antigen test (immunological assay reacts w/ a specific carb in the bacteria cell wall (antigen)
How do you detect antibodies in strep. pyog (group a strepto) ?
anti SLO (ASO) test
What does the presence of antibodies to streptolysin O confirm?