Question

I am looking for a detailed and well presented answer. Organize your work and think through the information. Make sure it is in your own words. You are expected to research the information. make sure to include your references.

What is the catalase test? Coagulase test?

What does it mean to be:

Catalase +

Catalase -

Coagulase +

Coagulase -

When working with an unknown that may be Staphylococcus (but you are not sure), how can the two tests help?

Give step by step detail of how to determine you are dealing with Staphylococcus and not an organism such as Streptococcus (next week topic).

Give step by step details on how to determine you are dealing with:

S. epidermidis

S. aureus

Please no handwritten or picture responses - only typed answers.

Answer 1

1)starting with the first one catalase test:

This is a test that is used to demonstrate the presence of enzyme catalase which catalyses the release of oxygen from hydrogen peroxide.this test is mainly used to differentiate bacteria that produce catalase enzyme from the ones that do not produce catalase

Eg:staphylococci(catalase producing) from streptococci(non-catalase producing bacteria)

2.Coagulase test:

the coagulase test is used to differentiate staphylococcus aureus which is coagulase positive(produce coagulase ) from Staphylococcus epidermis and staphylococcus saprophyticus that are coagulase negative(do not produce coagulase )

3)catalase+: catalase positive means the bacteria produce catalase enzyme and respire using oxygen it includes aerobes and facultative aerobes eg,staphylococci

4)catalase-: catalase negative means the bacteria do not produce the enzyme catalase they may be anerobes and facultative anerobes,they do not respire using oxygen

5)coagulase+: A coagulase positive test indicates the presence of staphylococcus aureus in this the coagulase reacts with prothrombin in blood rsulting in a complex staphylothrombin which enables the enzyme protease to convert fibrinogen to fibrin which results in clotting of blood

6)coagulase-:coagulase negative test indicate the prescence of S.epidermis or S.saprophyticus these are less virulent strains of staphylococci

7)while working with an unkown organisam may be bacteria after perfoming these tests

1)catalase test: performed by two methods

2coagulase test:

a)slide method:if there is clumping or foaming then it is a positive strain such as Staphylococcus aureus if there is no clumping then it is a catalase negative strain fpr coagulase

b)tube coagulase test: results are same as above after performing the test if there is a clot formation it is coagulase positive if there is no clot it is coagulase negative

8)there are certain differences among the by which you can identify it is aureus or epidermis

a) aureus colonies are large and smooth while the epidermis is small and round

b)aureus shows positive results in coagulase test while the epidermis is negative

c)aureus is golden in color where as epidermis colonies are white in color

these are some major easy identifications by which we can identify them