Random Tests Flashcards
What is beta haemolysis
When haemolysins completely destroy erythrocytes and metabolize the haemoglobin, this turns the agar a translucent yellow near the colonies
What is alpha haemolysis
Alpha haemolysis occurs when haemolysins damage the erythrocytes and reduce haemoglobin to methemoglobin. The agar turns an opaque green
What is gamma haemolysis
Gamma haemolysis occurs if the bacterium doesn’t produce haemolysins, mono change occurs
What is deep motility agar
Semisolid media with an agar concentration of 0.4%, this allows movement of motile bacteria while still preserving its form
Why is TTC added (motility test )
2,3,5-triphenyl tetrazolium chloride is added to enhance visibility of bacteria
- bacteria use TTC as an electron acceptor which turns it red and insoluble, indicating the presence of bacteria in the precipitated areas.
What is catalase
An enzyme produced by some aerobic species that hydrolyze hydrogen peroxide into oxygen and water
How is a catalase-positive organism indicated
Catalase-positive organisms produce vigorous bubbling upon the addition of hydrogen peroxide to the inoculated species
What does the oxidase test do
Detects cytochrome c oxidase (Complex IV) which can oxidize cytochrome c and catalyze they reduction of cytochrome c by p-aminomethylaniline oxalate (DPD)
What do oxidases do
Play a vital role in the electron transport chain during aerobic respiration, complex IV makes the final electron transfer from cytochrome c to the terminal electron acceptor, oxygen
