Diagnostic Bacteriology Flashcards
(30 cards)
What colour does gram negative stain
Purple
What colour does gram positive stain
Pink
What is the composition of the membrane of gram negative
2 outer membranes Has got lipopolysaccharide
What is the composition of the membrane of gram positive
1 outer membrane - cytoplasmic membrane Thick peptidoglycan
How do you stain the bacteria
Apply crystal violet
Iodine added to form complexes larger than crystal violet
Wash with alcohol (dehydration and peptidoglycan become tightened)
What is a cocci bacteria
Spheres
What is a bacilli bacteria
Round ended cylinders
What shape is staphylococci
Grapes
What shape is streptococci
Long chains
What is hemolytic activity good at differentiating
Gram positive bacteria such as staphylococcus, streptococcus and enterococcus
What does hemolytic test mean
Ability of microorganisms to produce hemolysins (enzymes that damage red blood cells)
What does gamma hemolysis
No hemolysis (no zone)
What does alpha hemolysis mean
Partial hemolysis (opaque zone)
What does beta hemolysis mean
Complete hemolysis (transparent zone)
What is lactose fermentation good for
Useful for differentaiting gram negative bacteria
How does lactose fermentation work
Include bile salts, crystole violet and lactose
See if bacteria can ferment lactose
What is the test result of lactose fermentation
It produces lactic acid
It is pink
What is catalase test useful in determine
Straphylococci - produces catalase
Streptococci - does not produce catalase
What does catalase break down
Hydrogen peroxide
Produces water and oxygen
What does coagulase test for
Discriminate between staphylococci
Aureus - produces coagulase
Other staphylococci - no coagulase
What does coagulase do
Processes prothrombin to thrombin
15 seconds
What bacteria is:
gram positive
catalase negative
a hemolytic
S. pneumoniae
S. mutans
What bacteria is:
gram positive
catalase negative
b hemolytic
S. agalactiae
S.pyogenes
What bacteria is:
gram positive
catalase negative
y hemolytic
E. faecium
E. faecalis
